The marine green and brown algae of Rodrigues (Mauritius, Indian ...

JOURNAL OF NATURAL HISTORY, 2004, 38, 2959–3020
The marine green and brown algae of Rodrigues (Mauritius, Indian
Ocean)
ERIC COPPEJANS{, FREDERIK LELIAERT{,
HEROEN VERBRUGGEN{, OLIVIER DE CLERCK{,
TOM SCHILS{, THOMAS DE VRIESE{ and DANIEL MARIE{
{Phycology Research Group, Biology Department, Ghent University,
Krijgslaan 281/S8, 9000 Ghent, Belgium;
e-mail: eric.coppejans@ugent.be
{Mauritius Oceanography Institute, France Centre, Victoria Avenue,
Quatre Bornes, Mauritius
The marine benthic green and brown macroalgae of Rodrigues, collected during
an expedition in October 2001, are documented and 18 of the 60 taxa of
Chlorophyta (53 species) and 18 species of Phaeophyceae are illustrated. Fifty
taxa of green and 12 taxa of brown algae are added to the existing species list of
the island. Turf algae and smaller epiphytic species are not or are only
sporadically included in this study. All records are listed with bibliographic,
biogeographic, taxonomic and nomenclatural comments. Infrageneric identification
keys are included. The new combination Caulerpa mexicana var. exposita is
proposed and the discovery of a new Udotea species is mentioned. The algal flora
of Rodrigues is of a typical Indian Ocean composition but appears to be
relatively poor when compared to the nearby island of Mauritius.
KEYWORDS: Algae, Chlorophyta, Indian Ocean, Mascarene Islands, Phaeophyceae,
Rodrigues, seaweeds, taxonomy.
Introduction
Rodrigues is a volcanic island, approximately 1.5 million years old. It is situated
in the south-western part of the Indian Ocean, between 19.39‡ and 19.50‡S, 560 km
east of Mauritius and 2200 km east of the coast of Mozambique. Politically, it
belongs to Mauritius. Rodrigues, Réunion and Mauritius constitute the Mascarene
Islands. These islands are on the southernmost tip of the Mascarene Ridge, a
plateau that stretches 2000 km in an arc across the Indian Ocean between the
Seychelles in the north and Mauritius in the south. The plateau sits in water
perhaps 4000 m deep, rising from these abyssal depths to level off in vast banks
sitting 80 m or shallower beneath the ocean surface. Where they emerge they form
the main islands of Mauritius and Seychelles as well as many smaller islands in
Journal of Natural History
ISSN 0022-2933 print/ISSN 1464-5262 online # 2004 Taylor & Francis Ltd
http://www.tandf.co.uk/journals
DOI: 10.1080/00222930410001695024

2960 E. Coppejans et al.
between. Rodrigues sits in the South Equatorial Current that runs from east to
west.
The island of Rodrigues sits on a submarine platform (an older volcano) of
55630 km. The island is 18.3 km long, 6.5 km wide and has as surface area of
107.8 km 2 (figure 1). The surrounding lagoon with numerous islets and the coral reef
cover 240 and 200 km 2 , respectively. The coastline of the island is 60.2 km long and
is composed of rocky stretches (especially at the headlands) alternating with sandy
beaches (mainly in the bays) and smaller stretches of rock boulders and pebble
shores. Locally, small (undercut) cliff walls (2–3 m high) occur, composed of eroded
fossil coral reefs. In front of (temporary) rivulets, silty-sandy areas develop. The
highest point of Rodrigues is Mont Limon, at 396 m in height. The slopes are rather
steep; narrow coastal plains fringe the central mountain. The east coast is most
wind-exposed and the reef is only 50 m away from the shore. Along the north-west,
west and south-west coast, on the other hand, it lies 4–8 km from the main island.
In general, the vast lagoon between the coastline and the reef is shallow, with
sandbanks appearing at low tide; there are some deeper tidal channels. At spring
low tides the intertidal zone locally extends several hundred metres. The bottom of
the lagoon is composed of silty sand, the amount of silt being dependent on the
distance from (temporary) rivulets. Locally, groups of coral heads with a more
luxuriant seaweed vegetation occur. These coral heads become more frequent
FIG. 1.
Sampling stations. See table 1 for a list of the stations and their GPS coordinates.
Map redrawn from Wells (1988). The outer grey line represents the fringing reef.

Marine green and brown algae of Rodrigues 2961
towards the fringing reef and finally form a continuous reef crest with some tide
channels.
There is no natural mangrove vegetation on the island. Rhizophora mucronata
Lamarck has recently been introduced in bays, mostly to stabilize silt runoff after
the drastic deforestation that has happened. The seagrass community is very limited
and occurs only in the low intertidal and shallow subtidal zones. It is composed of
only two seagrass species: Halophila ovalis (Braun) Hooker and H. stipulacea
(Forsskål) Ascherson.
The warmer season is from November until April with a maximum air
temperature of 28‡C and a mean water temperature of approximately 27.5‡C. The
cooler season is from May to October with a minimum air temperature of 20‡C and
a mean water temperature of 23‡C. Wet summers and dry winters characterize the
island. Cyclones (up to type 4) are relatively frequent, especially between January
and April.
Historically, the seaweeds of Rodrigues have remained understudied: Balfour
collected 39 species on Rodrigues during the Transit of Venus expedition in 1874.
They were identified by Dickie (1877a). A search in Silva et al. (1996) resulted in 42
taxa (15 chlorophytes, 11 phaeophytes, 15 rhodophytes and one cyanophyte).
In 1998 a large science programme, the Shoals of Capricorn Programme, was
launched in the Seychelles. This marine science, training and education programme
was run by the Royal Geographical Society (with the Institute of British
Geographers), in association with the Royal Society (UK). It was dedicated to
developing the knowledge and skills required for marine resource management and
conservation in the western Indian Ocean region. In 1999 the programme was
transferred to Mauritius and during 3 weeks in September and October 2001, 11
specialists in reef fauna and flora converged on Rodrigues for the Shoals of
Capricorn Marine Biodiversity Workshop. The first author participated as the
phycologist of the team, with Dr D. Marie as a Mauritian counterpart. De Clerck
et al. (2004) provide a treatment of the marine red algae collected during the same
expedition.
Material and methods
All the collection sites listed in this paper are indicated in figure 1 and are listed
in table 1 (including GPS coordinates). For the general position of Rodrigues in the
Indian Ocean see Schils et al. (2004: figure 1). The collecting period was between 18
September and 3 October 2001 with on-site laboratories and accommodation
provided by the Shoals of Capricorn Programme at Pointe Monier.
Most intertidal (shores, sandbanks, reef crest) and shallow subtidal (lagoon)
localities were sampled by wading and snorkelling. A limited number of scubadives,
down to 20 m, were done mainly in tidal channels and along the landward
and seaward slopes of the fringing reef. The fieldwork resulted in 282 herbarium
vouchers (HEC 14602–14884) and numerous formalin-preserved seaweed specimens.
The collection was deposited in the Ghent University Herbarium (GENT).
As collecting was carried out during a very short time span, a number of
seasonal species are most probably absent from this list. Moreover, small species
(turf algae, epiphytic species) have been collected only sporadically.
Part of the results presented here are included in the MSc thesis of De Vriese
(2002).

2962 E. Coppejans et al.
Table 1. Sampling sites (see also figure 1).
No. Name of site and comments Coordinates
1 Grand Bassin, day station 5 19‡41’404@S, 63‡18’939@E
2 Grand Bassin, day station 4 19‡41’370@S, 63‡20’749@E
3 Grand Bassin, day station 3 19‡41’630@S, 63‡21’282@E
4 Grand Bassin, day station 2 19‡41’733@S, 63‡21’575@E
5 Grand Bassin, day station 1 19‡41’685@S, 63‡22’256@E
6 Ile aux Fous 19‡39’023@S, 63‡22’934@E
7 Grand Paté 19‡39’307@S, 63‡24’951@E
8 Chaland 19‡40’074@S, 63‡24’659@E
9 Totor (D. Paupiah and M. Richmond) 19‡40’234@S, 63‡25’720@E
10 Grand Baie, outer reef slope (M. Richmond) 19‡39’047@S, 63‡26’381@E
11 Grand Baie, reef flat and lagoon 19‡39’876@S, 63‡27’422@E
12 Rivière Banane 19‡40’554@S, 63‡28’488@E
13 Cotton Bay, basalt 19‡40’774@S, 63‡29’481@E
14 Cotton Bay, reef front 19‡40’833@S, 63‡29’548@E
15 Cotton Bay, right-hand side, limestone cliff wall 19‡41’196@S, 63‡29’993@E
16 Gravier 19‡43’879@S, 63‡28’875@E
17 Port Sud-Est 19‡44’540@S, 63‡27’339@E
18 Ile Hermitage 19‡45’166@S, 63‡26’792@E
19 Grande Passe, lagoon 19‡46’030@S, 63‡26’137@E
20 Ile aux Chats 19‡46’479@S, 63‡25’871@E
21 Ile aux Chats 19‡46’800@S, 63‡26’100@E
22 Back reef in front of Ile aux Chats 19‡46’949@S, 63‡26’282@E
23 Petite Butte 19‡45’066@S, 63‡23’802@E
24 Petite Butte 19‡45’108@S, 63‡23’805@E
25 Petite Butte 19‡45’124@S, 63‡23’814@E
26 Plage Palmiste 19‡45’100@S, 63‡20’539@E
27 South-West Lagoon, sandbank 19‡47’150@S, 63‡21’572@E
28 South-West Lagoon, day station 3 19‡48’779@S, 63‡22’224@E
29 South-West Lagoon, day station 4 19‡49’217@S, 63‡22’373@E
30 South-West Lagoon, day station 5 19‡49’671@S, 63‡22’637@E
31 Back reef east of Passe Quatre Vingt Brisants 19‡49’894@S, 63‡22’698@E
All sites were sampled by E. Coppejans and D. Marie, other samplers’ names are indicated.
Arrangement and format of the list
The systematic arrangement of orders essentially follows that of Silva et al.
(1996). Families, genera and species are arranged alphabetically. Identification keys
to the species level are provided for genera represented by more than one species. It
should be noted that these keys are only applicable to the seaweed flora of
Rodrigues. The taxa indicated with an asterisk are new records for Rodrigues. For
each species, references are given, mainly to publications dealing with Indo-Pacific
algae. In these references, a description and/or illustration of the species in question
can be found. In addition, we add references to illustrations and descriptions in
recent photographic field guides from other regions: Littler and Littler’s (2000)
publication on Caribbean reef plants, Payri et al.’s (2000) guide to French Polynesian
algae, Huisman’s (2000) guide to Australian seaweeds, and Littler and Littler’s (2003)
photographic guide to South Pacific reef plants. The type locality is mentioned as at least
one distributional record. Taxa that are cited for descriptions and illustrations which are
listed ‘as’ refer to misapplied names, or ‘~’ where they are synonyms.
Then, the voucher specimens are cited [HEC, Herbarium Eric Coppejans; (zA),
also alcohol-preserved specimen; (zF), also formalin-preserved specimens; (zS),

Marine green and brown algae of Rodrigues 2963
also silica gel dried specimens] together with the exact location of the sampling sites,
indicated as ‘s.s.’ followed by the number of the respective site, as in figure 1 and
table 1. It should be emphasized that numerous species have been observed at
several sites but have not been collected at each of these sites. Therefore, the
voucher specimens do not indicate the known distribution of species around the
island.
The distribution in the Indian Ocean (largely from Silva et al., 1996) is given.
Exhaustive references are only added for the Mascarene Islands and for countries
that are not mentioned in Silva et al. (1996). The countries or regions are placed
alphabetically.
Notes regarding various aspects of taxonomy, systematics, nomenclature or
aberrant characters are added. The dimensions mentioned here are always those of
our specimens rather than the full ranges of the species.
Taxa that have been collected at Rodrigues by previous collectors, but were not
observed during this expedition, are mentioned under the heading ‘Unchecked data
from literature’. These are not included in the identification keys.
Results
CHLOROPHYTA
ULVALES
ULVACEAE
Enteromorpha Link
The species belonging to this genus have a simple and very variable
morphology, anatomy and cytology. Branching type (if present), diameter of
main axes as compared to side branches, morphology of the side branches and
branchlets are frequently used as morphological characters. Cell dimensions (in
surface view and on transverse sections), cell organization (possible presence of
longitudinal and/or transverse rows) are anatomical characters used in its
taxonomy. The number of pyrenoids in the chloroplasts is a cytological character
used for the identification of Enteromorpha species. The tropical taxa of this genus
have been poorly studied and they are mostly identified with Bliding’s (1963) work
on European representatives. A molecular phylogeny based on 5.8S rDNA and
ITS2 sequences (Malta et al., 1999: 443–454) demonstrates a monophyletic
Enteromorpha-clade that falls within the paraphyletic genus Ulva.
We identified our material of Enteromorpha and Ulva using monographs
on European representatives (Bliding, 1963, 1969; Koeman and van den Hoek,
1981; Koeman, 1985). A world-wide revision (including molecular analysis) is
imperative to ascertain whether tropical representatives are identical to the
temperate species.
Key to the species from Rodrigues
1 Thallus unbranched, a single pyrenoid per cell . . . . . . . . E. intestinalis
– Thallus branched, most cells with more than one pyrenoid . . . . . . . . 2
2 Cells in the lower basal regions mostly more than 25620 mm in size; cells in the apical
and middle region mostly containing two to nine pyrenoids . . . . E. clathrata
– Cells in the lower basal regions mostly less than 25620 mm in size; cells in the apical
and middle region mostly containing two to five pyrenoids (one pyrenoid in up to 50%
of the cells) . . . . . . . . . . . . . . . . . . . . . . 3

2964 E. Coppejans et al.
3 Thallus without uniseriate laterals . . . . . . . . E. flexuosa subsp. flexuosa
– Thallus with uniseriate laterals . . . . . . . . . E. flexuosa subsp. paradoxa
*Enteromorpha clathrata (Roth) Greville, 1830: lxvi, 181
References: Bliding, 1963: 107–113, figures 64–69; Jaasund, 1976: 1, figure 2; Tseng,
1984: 252, pl. 125, figure 4; Cribb, 1996: 29, figure p. 28; Kraft, 2000: 525,
figure 8; Skelton and South, 2002: 160, figure 22A, B.
Type locality. Europe.
Voucher. HEC 14859 (zF), 30 September 2001, south-western part of the
lagoon (s.s. 27).
Ecology. On shell and coral fragments on a sandbank, intertidal zone.
Distribution. Aldabra Islands, Australia, Bahrain, Bangladesh, Chagos Archipelago,
India, Iran, Iraq, Kenya, Kuwait, Laccadives, Maldives, Mauritius (Børgesen,
1946: 8), Nicobar Islands, Pakistan, Rodrigues (this paper), Saudi Arabia,
Seychelles, Singapore, South Africa, Tanzania, Thailand, Yemen.
Note. Our material agrees very well with the description and illustrations of
Bliding (1963).
*Enteromorpha flexuosa (Wulfen) J. Agardh, 1883: 126–128, subsp. flexuosa
References: Bliding, 1963: 73–79, figures 38–40; Tseng, 1984: 254, pl. 126, figure 2;
Kraft, 2000: 523, figure 7A–E; Littler and Littler, 2000: 300, figure p. 301; Payri
et al., 2000: 62, figure p. 63.
Type locality. Diuno, near Trieste, Italy.
Vouchers. HEC 14707 (zF), 20 September 2001, Rivière Banane; HEC
14785, 25 September 2001, Passe Grand Bassin (s.s. 3); HEC 14833 (zF), 27
September 2001, Baie de l’Hermitage (s.s. 22).
Ecology. Epilithic in the upper intertidal zone, but also collected in the subtidal
where it has been observed as an epiphyte on Liagora ceranoides.
Distribution. Australia, Bahrain, Diego Garcia atoll, India, Indonesia (Bali
and Java), Kuwait, Laccadives, Madagascar, Malaysia, Mauritius (Børgesen,
1940: 9; 1946: 8), Pakistan, Rodrigues (this paper), Saudi Arabia, Seychelles,
Singapore, Somalia, South Africa, Tanzania, Yemen.
Note. Our material agrees very well with the description and illustrations of
Bliding (1963).
*Enteromorpha flexuosa (Wulfen) J. Agardh subsp. paradoxa (J. Agardh)
Bliding, 1963: 79
References: Bliding, 1963: 79–85, figures 42–45; Kraft, 2000: 525, figure 7F; Littler
and Littler, 2000: 302, figure p. 303.
Syntype localities. Bangor, Caenarvon, Wales, UK; Brighton, England, UK.
Voucher. HEC 14828 (zF), 27 September 2001, Baie de l’Hermitage (s.s. 20).
Ecology. Epilithic at the foot of a limestone cliff wall, at about mean low water.
Distribution. Diego Garcia Atoll, India, Indonesia, Madagascar, Mauritius
(Børgesen, 1940: 9), Rodrigues (this paper), Singapore, Thailand.
Note. Our material agrees very well with the description and illustrations of
Bliding (1963).

Marine green and brown algae of Rodrigues 2965
Enteromorpha intestinalis (Linnaeus) Nees, 1820: index
References: Bliding, 1963: 139–141, figures 87, 88; Tseng, 1984: 254, pl. 126, figure 3;
Littler and Littler, 2000: 302, figure p. 303.
Type locality. ‘In Mari omni’.
Vouchers. HEC 14641 (zF), 19 September 2001, Gravier; HEC 14839, 27
September 2001, Port Sud-Est (s.s. 17).
Ecology. Locally common on sand-covered rocky substratum in the upper
intertidal zone (HEC 14641); on dead shells and coral debris on silty sand along
the beach in the lower part of the intertidal zone; exposed at low tide (HEC
14839).
Distribution. Andaman Islands, Australia, Bahrain, Bangladesh, India, Indonesia
(Java), Yemen, Kuwait, Laccadives, Malaysia, Pakistan, Rodrigues (Dickie, 1877a:
7), Seychelles, Singapore, South Africa, Sri Lanka.
Note. Our material agrees very well with the description and illustrations of
Bliding (1963). Our specimens are relatively narrow (maximum 2 mm wide), but
do show marked constrictions.
General remarks on the distribution of Enteromorpha in the Mascarene Islands
Seven Enteromorpha species have been recorded from Mauritius: E. clathrata, E.
compressa (Linnaeus) Nees, E. flexuosa, E. prolifera (O. F. Müller) J. Agardh (~E.
compressa (Linnaeus) Nees var. prolifera (O. F. Müller) Greville) (Børgesen, 1940:
8–10), E. muscoides (~E. ramulosa (J. E. Smith) Carmichael) (Børgesen, 1946: 8),
E. kylinii Bliding, E. linza (Linnaeus) J. Agardh (Jagtap, 1993: table I). Two species,
E. muscoides (~E. crinita Nees) and E. prolifera, were also recorded from Réunion,
by Jadin (1935: 154) and Montagne and Millardet (1862: 4), respectively. E.
muscoides (~E. ramulosa) and E. compressa have previously been reported from
Rodrigues by Dickie (1877a) but were not found in our collections.
Unchecked data from literature
Enteromorpha compressa (Linnaeus) Nees, 1820: index
Mentioned by Dickie (1877a) but not among our recent collection.
Enteromorpha muscoides (Clemente and Rubio) Cremades, in Cremades and
Pérez-Cirera, 1990: 489
Mentioned by Dickie (1877a~E. ramulosa (J. E. Smith) Carmichael, in W.
Hooker) but not among our recent collection. Cremades and Pérez-Cirera (1990:
489) are of the opinion that Ulva muscoides and U. ramulosa are conspecific.
Gayralia Vinogradova
*Gayralia oxysperma (Kützing) Vinogradova ex Scagel et al., 1989: 72
References: Abbott and Hollenberg, 1976: 68 (~Monostroma oxyspermum
(Kützing) Doty); Golden and Garbary, 1984: 327, figures 31–41 (~Monostroma
oxyspermum); Cribb, 1996: 37, figure p. 36 (~Monostroma oxyspermum); Littler
and Littler, 2000: 298, figure p. 299.
Type locality. Baltic Sea, Germany.

2966 E. Coppejans et al.
Vouchers. HEC 14644, 19 September 2001, Gravier (s.s. 16); HEC 14676
(zF), 20 September 2001, Rivière Banane (s.s. 12).
Ecology. Epilithic in the high intertidal zone.
Distribution. West Australia, Burma, Kenya, Madagascar, Mauritius (Børgesen,
1940: 8), Rodrigues (this paper).
Note. Golden and Garbary (1984) carried out culture experiments and suggested
the merging of the genera Monostroma, Gayralia and Protomonostroma
and recognition of these three groups on a subgeneric level. We follow Vinogradova
(1969) and Silva et al. (1996: 740) in keeping them separate because of the
different life cycles in Monostroma and Gayralia.
Ulva Linnaeus
Like the genus Enteromorpha, Ulva is characterized by a limited number of
useful characters to distinguish between species. As in Enteromorpha, the general
morphology of the thallus, the thickness of the blade and the number of pyrenoids
per cell are the taxonomic characters used. See the remarks on the genus
Enteromorpha about the poor knowledge of tropical representatives and the need
for molecular work in both genera.
Key to the species from Rodrigues
1 Thallus composed of long and broad blades with scattered perforations . U. pertusa
– Thallus composed of small, crisp, undulate bladelets, forming small rosettes; bladelets
not perforated. . . . . . . . . . . . . . . . . . . U. rigida
*Ulva pertusa Kjellman, 1897: 4–7, pl. 1, pl. 3, figures 1–8
References: Jaasund, 1976: 3; Tseng, 1984: 258, pl. 128, figure 2.
Syntype localities. Various in Japan.
Vouchers. HEC 14677 (zF), 20 September 2001, Rivière Banane (s.s. 12);
HEC 14883, 3 October 2001, western part of Cotton Bay (s.s. 13).
Ecology. Epilithic in the intertidal (HEC 14667) and on coral debris on sand
about mean low tide (HEC 14883).
Distribution. Indonesia (Sumba), Kenya, Mauritius (Jagtap, 1993: table I),
Rodrigues (this paper), Singapore, Tanzania, Yemen.
Note. Typical for this species are the irregularly placed small perforations of
different sizes. Other species with perforations are U. reticulata Forsskål (more
or less strap-shaped with numerous large perforations of mixed diameter, up to
the blade margin), U. pulchra Jaasund with perforations limited to the central
part of the orbicular blade, becoming gradually smaller towards the margin of
the perforated part) and U. fenestrata Postels and Ruprecht, described from
Siberia but mentioned from the Indian Ocean by Durairatnam (1961: 17, pl. 1,
figure 2, pl. 21, figure 1). The latter species is irregularly perforated and the perforations
are crenulate.
*Ulva rigida C. Agardh, 1823: 410–411
References: Baardseth, 1941: 7–8; Jaasund, 1976: 3, figure 8 (f. tropica); Kraft, 2000:
533, figure 11; Littler and Littler, 2000: 306, figure p. 307.
Lectotype locality. Cádiz, Spain.

Marine green and brown algae of Rodrigues 2967
Voucher. HEC 14743 (zF), 22 September 2001, Grand Baie (s.s. 11).
Ecology. Subtidal, epilithic on dead coral in a shallow part of the
lagoon.
Distribution. Aldabra Islands, Arabia (SE coast), Australia, India, Kenya,
Kuwait, Laccadives, Madagascar, Mauritius (Kalugina-Gutnik, 1985: 97),
Mozambique, Nicobar Islands, Réunion, Rodrigues (this paper), Seychelles,
Somalia, South Africa, Sri Lanka, Yemen.
General remarks on the distribution of Ulva in the Mascarene Islands
U. fasciata Delile, U. lactuca Linnaeus (Børgesen, 1940: 10) and U. latissima
auctorum (Børgesen, 1946: 9) have been mentioned from Mauritius but were not
recently found on Rodrigues, although the last ones were mentioned by Dickie
(1877a, b).
Unchecked data from literature
Ulva lactuca Linnaeus
See Silva et al. (1996) but not among our recent collection.
Ulva latissima auctorum
Mentioned by Dickie (1877a) but not among our recent collection. According
to Silva et al. (1996: 748), this name has traditionally been misapplied to
representatives of the genus with very broad, sheet-like fronds, the type being
referable to Laminaria saccharina (Linnaeus) Lamouroux.
CLADOPHORALES
ANADYOMENACEAE
Microdictyon Decaisne
Microdictyon tenuius J. Gray, 1866: 69
(figure 2)
References: Setchell, 1929: 486–490, figures 6–9; Børgesen, 1940, 1946, 1954 (as M.
agardhianum Decaisne).
Type locality. Near Jeddah, Saudi Arabia.
Voucher. HEC 14849 (zF), 29 September 2001, Grand Paté (s.s. 7).
Ecology. On coral fragments in gulleys between coral heads, mixed with
other small algae; at 15 m depth.
Distribution. India, Madagascar, Mauritius (Børgesen, 1940: 25–28, figure 7,
pl. 2, figure 1; 1946: 18; 1954: 5), Rodrigues (Dickie, 1877a: 7, as M. agardhianum
Decaisne), Sri Lanka.
Note. M. tenuius is placed in the Annuliferae group, section Eumicrodictyon
on account of the anastomosis of the filaments by means of smooth rings on the
cell apices, the mostly opposite branching pattern and the basal attachment over
a large area of the thallus (Setchell, 1929: 478, 486). The separation between the
species in the section Eumicrodictyon (and in the genus altogether) is rather
ambiguous. Millar (1999: 66) argues that characters defined by Setchell (1929)
are untenable and that the genus may be represented by only four of its 18
current species. Representatives of the genus in the western Indian Ocean are

2968 E. Coppejans et al.
FIGS 2–6. Chlorophyta. (2) Microdictyon tenuius, detail of branching and anastomosing
patterns (HEC 14849). (3) Bryopsis pennata var. pennata, branchlets of last order
contiguous and in a single plane (HEC 14796 p.p.). (4) Bryopsis pennata var. leprieurii,
branchlets of last order interrupted and in a single plane (HEC 14757). (5) Bryopsis pennata
var. secunda, branchlets of last order curved in one direction (HEC 14796 p.p.). (6)
Chamaedoris delphinii (HEC 14617). Scale bars: 250 mm (2); 5 mm (3–5); 1 cm (6).
currently under study. We refer to Silva et al. (1996: 934–936) for a discussion
of the complex nomenclature of M. tenuius.
CLADOPHORACEAE
Chaetomorpha Kützing
*Chaetomorpha brachygona Harvey, 1858: 87–88, pl. XLVI A
References: Taylor, 1928: 60; Sartoni, 1992: 297–299, figure 4D.
Syntype localities. Key West, Florida, USA; mouth of Rio Bravo, border of
Mexico and Texas, USA.
Vouchers. HEC 14782 (zF), 25 September 2001, Passe Grand Bassin (s.s. 3);
HEC 14862, 30 September 2001, south-western part of the lagoon (s.s. 27).
Ecology. Intertidal and infralittoral fringe, forming loose-lying tufts of intricated
filaments mixed with other filamentous algae.

Marine green and brown algae of Rodrigues 2969
Distribution. Bangladesh, Diego Garcia Atoll, India, Indonesia (Bali), Kenya,
Maldives (Addu Atoll), Rodrigues (this paper), Somalia, Sri Lanka.
Chaetomorpha sp.
Voucher. HEC 14728 (zF), 21 September 2001, Petite Butte (s.s. 24).
Ecology. Hanging down from an overhang of a limestone wall in the supralittoral
fringe (just above the Bostrychia zone).
Note. The field identification of this collection was Rhizoclonium africanum
Kützing because of its gross morphology, colour and ecology. However, microscopic
analysis showed that the cell diameter (20–25 mm) and cell wall thickness
(3–5 mm) are smaller than in R. africanum and the typical intercalary rhizoids
are missing.
Cladophora Kützing
Key to the species from Rodrigues
1 Thallus composed of interwoven filaments; attached to the substrate at several places
by means of rhizoids developing from the proximal poles of the stolon-like
filaments . . . . . . . . . . . . . . . . . . . C. coelothrix
– Thallus forming erect tufts, attached to the substrate at a single point; main axes
pseudodichotomous, ending in acropetal, often falcate terminal branch systems C. vagabunda
*Cladophora coelothrix Kützing, 1843: 272
References: van den Hoek, 1982: 47–52, figures 11–29; Børgesen, 1939: 72–73,
figure 15; Sartoni, 1992: 300, figure 5B; Leliaert and Coppejans, 2003: 50,
figure 2.
Type locality. Golfo di Genova, Italy.
Vouchers. HEC 14620, HEC 14630, 18 September 2001, western part of
Cotton Bay (s.s. 13).
Ecology. Epiphytic on Digenea simplex and Gelidiopsis on vertical walls of
intertidal pools.
Distribution. Australia, Chagos Archipelago (Egmont Atoll), Christmas
Island, India, Iran, Kuwait, Pakistan, Rodrigues (this paper), Saudi Arabia,
South Africa, Somalia.
Note. Cladophora coelothrix is very similar to C. socialis Kützing, but the
cell diameter of the former is about twice as large (55–140 mm) as that of the
latter (25–55 mm).
*Cladophora vagabunda (Linnaeus) van den Hoek, 1963: 144
References: van den Hoek, 1963: 144–148, pls 33, 36–38; 1982: 137–150,
figures 264–294; Jaasund, 1976: 7, figures 15, 16; Sartoni, 1992: 304, figure 6C–
E; Kraft, 2000: 562, figure 21; Littler and Littler, 2000: 324, figure p. 325;
Leliaert and Coppejans, 2003: 70–71, figures 14A, B, 15.
Lectotype locality. Selsey, Sussex, England, UK.
Vouchers. HEC 14783a (zF), HEC 14783b, HEC 14784a (zF), HEC
14784b, 25 September 2001, Passe Grand Bassin (s.s. 30); HEC 14861, 30
September 2001, south-western part of the lagoon (s.s. 27).

2970 E. Coppejans et al.
Ecology. Epilithic on coral rubble in the intertidal and the infralittoral
fringe.
Distribution. Australia, India, Indonesia (Sunda Strait), Kenya, Laccadives,
Madagascar, Malaysia, Maldives, Mauritius (Børgesen, 1940: 34–35, figure 10;
1946: 21–24, figures 8a, b, 9, 10), Nicobar Islands, Pakistan, Rodrigues (this
paper), Seychelles, Singapore, Somalia, Sri Lanka, Tanzania, Thailand, Yemen.
Note. Cladophora vagabunda has frequently been mentioned as C. mauritiana
Kützing. The latter species has been synonymized with the former by Børgesen
(1940: 35). This species is closely related to C. dalmatica Kützing and C. laetevirens
(Dillwyn) Kützing. Distinction between both is based on cell dimensions
and the maximum number of laterals per cell.
General remarks on the distribution of Cladophora in the Mascarene Islands (see
table 2)
Twelve Cladophora species have previously been recorded in the Mascarene
Islands (11 from Mauritius, two for Réunion and none for Rodrigues) (table 2). Of
these, three species (C. albida, C. echinus and C. sericea) are doubtful records since
their distribution pattern would normally be restricted to temperate regions. Two
other species (C. patentiramea and C. saviniana) are most likely conspecific with C.
coelothrix (based on the original descriptions and illustrations) while C. inserta is
probably a missapplied name for either C. vagabunda or C. dalmatica.
Only two species were collected from Rodrigues. C. vagabunda has been
recorded from both Rodrigues and Mauritius; C. coelothrix had only been reported
from Mauritius (as C. patentiramea).
SIPHONOCLADACEAE
Boodlea Murray and De Toni
*Boodlea composita (Harvey) Brand, 1904: 187–190
References: Egerod, 1952: 361–362, figure 6a; Børgesen, 1940: 21–25; Magruder and
Hunt, 1979: 17, figure 1 p. 16; Tseng, 1984: 276, pl. 137, figure 1; Sartoni, 1992:
306–307; Cribb, 1996: 13, figure p. 12; Leliaert et al., 1998: 184, figures 14–20;
Huisman, 2000: 238, figures; Kraft, 2000: 569, figure 24A–C; Littler and Littler,
2000: 326, figure p. 327; Littler and Littler, 2003: 200, top figure p. 201.
Type locality. Mauritius.
Vouchers. HEC 14639 (zF), 18 September 2001, western part of Cotton Bay
(s.s. 13); HEC 14643 (zF), 19 September 2001, Gravier (s.s. 16).
Ecology. Abundant in the intertidal, exposed at low tide and locally colouring
this zone light green.
Distribution. Bangladesh, Chagos Archipelago (Egmont Atoll), Diego Garcia
Atoll, India, Indonesia (Java), Kenya, Laccadives, Madagascar, Malaysia, Maldives,
Mauritius (Børgesen, 1940: 21–25, figure 6; 1946: 15–16, figure 5), Mozambique,
Nicobar Islands, Pakistan, Réunion (Jadin, 1935: 155), Rodrigues (this paper),
Seychelles (including Mahé Island), Somalia, South Africa, Sri Lanka, Tanzania,
Thailand, Yemen.
Note. Taxonomic studies have demonstrated unclear boundaries between
Boodlea, Phyllodictyon, Struveopsis and some Cladophoropsis species (Børgesen,
1913; Egerod, 1952; Kooistra et al., 1993; Leliaert et al., 1998). Recent molecular

Marine green and brown algae of Rodrigues 2971
studies based on partial LSU rRNA gene sequences (Leliaert et al., 2003) reveal
that the above genera are very closely related, favouring the recognition of a
single genus.
Chamaedoris Montagne
*Chamaedoris delphinii (Hariot) Feldmann and Børgesen, in Børgesen, 1940: 16–20,
21 footnote, figure 5
(figure 6)
References: Børgesen, 1933: 5–9, figures 3–5; 1940: 16–20, figure 5; Jaasund, 1976:
11, figure 22; Sartoni, 1992: 308–311, figure 8.
Type locality. Fort Dauphin, Madagascar.
Voucher. HEC 14617, 18 September 2001, western part of Cotton Bay (s.s. 13).
Ecology. Frequent on vertical walls of intertidal pools, continuously submerged.
Growing in small, isolated clusters.
Distribution. Kenya, Madagascar, Mauritius (Børgesen, 1940: 16–21,
figure 5, pl. 1), Mozambique, Rodrigues (this paper), Somalia, South Africa,
Tanzania.
Note. C. delphinii differs from the other Chamaedoris species by the lack of
small apical cells on the stipe.
Cladophoropsis Børgesen
Key to the species from Rodrigues
1 Filaments dark green, rigid, often sympodially branched, aseptate rhizoids sprouting
from the base of most cells; apical cells 180–260 mm in diameter . . . C. herpestica
– Filaments medium to light green, monopodially branched, no descending rhizoids
sprouting from the base of the cells, short hapteroidal rhizoids present throughout the
thallus; apical cells 60–120 mm in diameter . . . . . . . . . C. sundanensis
*Cladophoropsis herpestica (Montagne) Howe, 1914: 31
References: Egerod, 1971: 123, figures 1–9; Sartoni, 1986: 365, figure 6A; 1992:
311; Womersley, 1984: 184–185, figures 58B, 59C; Kraft, 2000: 575,
figure 25E, F.
Type locality. Bay of Is, New Zealand.
Vouchers. HEC 14724 (zF), HEC 14727 (zF), 21 September 2001, Petite
Butte (s.s. 24); HEC 14823 (zF), 27 September 2001, Ile Hermitage (s.s. 18).
Ecology. Epilithic in the intertidal as well as on the slope of a tide channel
of the lagoon, 2 m deep.
Distribution. Australia, Malaysia, Rodrigues (this paper), Seychelles, Somalia,
South Africa.
*Cladophoropsis sundanensis Reinbold, 1905: 147
References: Børgesen, 1935: 10–11, figure 1; Egerod, 1974: 141, figures 32–36;
1975: 46, figures 8–10; Jaasund, 1976: 11, figure 24; Tseng, 1984: 274, pl. 136,
figure 1; Payri et al., 2000: 72, figure p. 63; Leliaert et al., 2001: 452,
figures 6–8.
Syntype localities. Various in Indonesia, including Solor and Semau.

2972 E. Coppejans et al.
Table 2.
Cladophora species previously recorded for Mauritius and Réunion with notes on
their taxonomy and distribution.
Species recorded for Mauritius
Cladophora albida (Nees)
Kützing
Cladophora echinus (Biasoletto)
Kützing
Cladophora inserta Dickie
f. inserta
Cladophora inserta Dickie
f. ungulata (Brand) Setchell
Cladophora patentiramea
(Montagne) Kützing
Cladophora prolifera (Roth)
Kützing
Cladophora saviniana
Børgesen
Cladophora sericea (Hudson)
Kützing
Notes on taxonomy and distribution
Recorded for Mauritius by Dickie
(1874: 199). Widely distributed in the
temperate zones of the northern and
southern hemispheres. The occurrence
of this species in tropical areas remains
uncertain according to van den Hoek et al.
(1990) and van den Hoek and Chihara (2000).
Recorded for Mauritius by Børgesen
(1948: 17–18, figure 8a–c).
Uncertain record: based on the description and
illustrations of Børgesen (1948: 17–18, figure 8)
the specimens from Mauritius lack the typical
rhizoids developing from the basal poles
of the cells. According to van den Hoek
(1963) and van den Hoek and Chihara
(2000) this species only occurs in southern Europe.
Recorded for Mauritius by Børgesen
(1946: 25–28, figures 11, 12: forma typica;
1948: 9–10, figure 2: forma ungulata). Based on
Børgesen’s descriptions and illustrations the
Mauritian specimens most probably belongs
to either C. vagabunda or C. dalmatica Kützing.
Recorded for Mauritius by Børgesen (1940: 36–37,
figure 12). Based on Børgesen’s description and
illustrations the Mauritian specimens belong to
C. coelothrix. According to van den Hoek and
Chihara (2000: 37) C. patentiramea possibly
represents a calm-water form of C. coelothrix.
Recorded from Mauritius (Silva et al., 1996: 779).
This species, described from Mauritius, is
characterized by acropetal terminal branch-systems
and attachment by rhizoids developing from
the basal poles of basal cells (Børgesen, 1948: 10–13,
figures 3, 4; pl. I, figure 1). On the basis of
Børgesen’s description and illustrations
C. saviniana most likely refers to C. coelothrix
(growth forms with acropetal organization as
described by van den Hoek, 1982: 47–48, pl. 2).
This species has been recorded from Réunion by
Montagne and Millardet (1862: 3~Cladophora ovoidea
Kützing). C. sericea occurs in warm to cold temperate
regions with extensions into the Arctic (van den Hoek,
1982: 96). The Mauritian record (and all other tropical
records) remain uncertain.

Species recorded for Mauritius
Cladophora socialis Kützing Recorded from Mauritius by Børgesen (1946: 28–29).
According to Børgesen, specimens reported from
Réunion by Jadin (1935: 155) as Cladophora repens
Harvey var. colombensis Grunow are referable
to C. socialis and Cladophoropsis sundanensis.
C. patentiramea f. longiarticulata, recorded from
Mauritius by Børgesen (1940: 36–37, figure 12),
was later reduced to a synonym of
C. sociales by Børgesen (1946: 28).
Cladophora timorensis
G. Martens
Cladophora vagabunda
(Linnaeus) van den Hoek
Cladophora valonioides (Sonder)
Kützing
Marine green and brown algae of Rodrigues 2973
Table 2. (Continued ).
Notes on taxonomy and distribution
Recorded from Mauritius by Børgesen (1940:
35–36, figure 11).
This species was recorded from Mauritius under three
different names: Cladophora mauritiana, described from
Mauritius by Kützing (1849: 399), was reduced to a
synonym of C. fascicularis (Mertens ex C. Agardh)
Kützing by Børgesen (1940: 35). Both species were
placed in the synonymy of C. vagabunda by
van den Hoek (1982: 137). Børgesen (1946: 18–21,
figures 6, 7) reported Cladophora hauckii
Børgesen from Mauritius, a species regarded as a
taxonomic synonym of C. vagabunda by van den Hoek
(1963: 147).
C. vagabunda is widely distributed in all tropical and
temperate seas (van den Hoek and Chihara, 2000: 184).
Recorded from Mauritius by Børgesen (1940: 35–36,
figure 11).
Cladophora vaughanii Børgesen Described from Mauritius by Børgesen (1948: 13–17,
figures 5–7); since then only recorded from the type
locality and Pakistan (Silva et al., 1996: 784).
Voucher. HEC 14673 (zF), 19 September 2001, Gravier (s.s. 16).
Ecology. Horizontal, sand-covered rock substratum in the intertidal.
Distribution. Aldabra Islands, Diego Garcia Atoll, India, Indonesia (Java),
Kenya, Malaysia, Maldives, Mauritius (Børgesen, 1940: 21; 1946: 15), Réunion
(Payri, 1985: 640), Rodrigues (this paper), Seychelles, Singapore, Somalia,
Tanzania, Thailand.
General remarks on the distribution of Cladophoropsis in the Mascarene Islands
Cladophoropsis herpestica has not been reported from Mauritius but C. javanica
(Kützing) Silva mentioned from that island (Børgesen, 1946: 15~C. zollingeri
(Kützing) Reinbold) was not collected on Rodrigues.
Dictyosphaeria Decaisne ex Endlicher
Key to the species from Rodrigues
1 Undisrupted thalli hollow, older specimens cup-shaped . . . . . D. cavernosa
– Thalli solid, extremely tough . . . . . . . . . . . . . D. versluysii

2974 E. Coppejans et al.
Dictyosphaeria cavernosa (Forsskål) Børgesen, 1932
References: Børgesen, 1932: 2; Egerod, 1952: 350–351, figures 1b–f, 2f, g; Jaasund,
1976: 15, figure 32; Magruder and Hunt, 1979: 27, figure 1 p. 26; Tseng, 1984:
268, pl. 133, figure 5; Moorjani and Simpson, 1988: 15, pl. 24; Sartoni, 1992: 319,
figure 13A; Cribb, 1996: 29, figure p. 28; Leliaert et al., 1998: 188, figures 30–33;
Huisman, 2000: 240, unnumbered figure; Kraft, 2000: 578, figure 27A, B; Littler
and Littler, 2000: 332, figure p. 333; Payri et al., 2000: 76, figure p. 77; Littler and
Littler, 2003: 202, bottom figure p. 203.
Syntype localities. ‘Gomphodae’ (Al-Qunfudhah), Saudi Arabia; Mokha, Yemen.
Vouchers. HEC 14636, 18 September 2001, western part of Cotton Bay
(s.s. 13); HEC 14788, 25 September 2001, Passe Grand Bassin (s.s. 2).
Ecology. Epilithic in the lower part of the intertidal zone.
Distribution. Aldabra Islands, Amirante Islands, Andaman Islands, Australia,
Bahrain, Bangladesh, Cargados Carajos, Chagos Archipelago, Cosmoledo Atoll,
Diego Garcia Atoll, India, Indonesia, Kenya, Kuwait, Laccadives, Malaysia,
Maldives, Mauritius (Børgesen, 1940: 12; 1946: 13–14), Mozambique, Nicobar
Islands, Qatar, Réunion (Jadin, 1935: 157 and Montagne and Millardet, 1862:
4~Dictyosphaeria favulosa (C. Agardh) Decaisne ex Endlicher, Payri, 1985: 640),
Rodrigues (Dickie, 1877a: 7), Saudi Arabia, Saya de Malha Bank, Seychelles,
Singapore, Somalia, South Africa, Sri Lanka, Tanzania, Thailand.
*Dictyosphaeria versluysii Weber-van Bosse, 1905: 144
References: Egerod, 1952: 351, 354–355, figures 1a, 2h–k; Jaasund, 1976: 15,
figure 33; Magruder and Hunt, 1979: 27, figure 2 p. 26; Tseng, 1984: 270, pl. 134,
figure 2; Moorjani and Simpson, 1988: 15, pl. 24; Sartoni, 1992: 319–321,
figures 13B, 14A, B; Allen and Steene, 1994: 20; Cribb, 1996: 29, figure p. 28;
Leliaert et al., 1998: 188, 190, figures 37–39; Littler and Littler, 2000: 334,
figure p. 335; Payri et al., 2000: 76, figure p. 77; Skelton and South, 2002: 162,
figure 23C, D; Littler and Littler, 2003: 200, bottom figure p. 201.
Syntype localities. ‘Plusieurs récifs dans l’Archipel Malaisien’.
Voucher. HEC 14624, 18 September 2001, western part of Cotton Bay (s.s. 13).
Ecology. Frequent on horizontal rock substrate in middle to low intertidal.
Distribution. Aldabra Islands, Chagos Archipelago, Indonesia, Kenya,
Madagascar, Maldives, Mauritius (Børgesen, 1940: 12–15, figures 1, 2a, 3),
Mozambique, Réunion (Payri, 1985: 640~Dictyosphaeria setchellii Børgesen),
Rodrigues (this paper), Seychelles, Somalia, South Africa, Tanzania, Thailand.
Phyllodictyon Gray
*Phyllodictyon anastomosans (Harvey) Kraft and Wynne, 1996: 139
References: Børgesen, 1952: 7–8, figure 3 (~Struvea anastomosans (Harvey) Piccone
and Grunow ex Piccone), Egerod, 1952: 359–361, figure 4, pl. 31; 1971: 123–125,
figures 10–16 (both~Struvea anastomosans); Tseng, 1984: 276, pl. 137, figure 2
(~Struvea anastomosans); Sartoni, 1992: 317–319, figure 12B, C (~Struvea
anastomosans); Coppejans et al., 1995a: 96, figure 38 (~Struvea anastomosans);
Kraft and Wynne, 1996: 131, figures 16–20; Leliaert et al., 1998: 186–187,
figures 23–24; Littler and Littler, 2000: 328, figure p. 329; Payri et al., 2000: 74,
figure p. 75.

Marine green and brown algae of Rodrigues 2975
Type locality. Fremantle, Western Australia.
Voucher. HEC 14827 (zF), 27 September 2001, Baie de l’Hermitage (s.s. 19).
Ecology. Very abundant as loose-lying balls on the silty-sandy bottom of the
lagoon, subtidal, 22 to24 m. Co-occurring with balls of Boodlea composita.
Distribution. Aldabra Islands, Australia, Diego Garcia Atoll, India, Indonesia
(Java), Kenya, Laccadives, Malaysia, Maldives, Mauritius (Børgesen, 1952: 7–8,
figure 3; 1953: 5), Mozambique, Pakistan, Rodrigues (this paper), Seychelles, Somalia,
South Africa, Sri Lanka, Tanzania (Coppejans et al., 2000: 65), Thailand, Yemen.
Note. The distinction between Boodlea composita and Phyllodictyon anastomosans
is unclear. Traditionally the former is distinguished from the latter by the
formation of three-dimensional net-like thalli lacking a stipe, while P. anastomosans
is characterized by stipitate, reticulate, monostromatic blades. Mature thalli
of P. anastomosans, however, form three-dimensional blades that anastomose
with other blades resulting in three-dimensional net-like thalli with obscure
stipes. Comparison of partial LSU rRNA of these two species (Leliaert et al.,
2003) reveals nearly identical gene sequences.
Ventricaria Olsen and West
*Ventricaria ventricosa (J. Agardh) Olsen and West, 1988: 104
References: Jaasund, 1976: 13, figure 27 (~Valonia ventricosa J. Agardh); Magruder
and Hunt, 1979: 35, figure 1 p. 34; Tseng, 1984: 272, pl. 135, figure 1 (~Valonia);
Sartoni, 1992: 323, figure 14E; Allen and Steene, 1994: 21; Cribb, 1996: 37,
figure p. 36; Huisman, 2000: 243, unnumbered figure; Littler and Littler, 2000:
336, figure p. 337; Payri et al., 2000: 80, figure p. 81; Littler and Littler, 2003:
204, bottom figure p. 205.
Lectotype locality. Guadeloupe, West Indies.
Vouchers. HEC 14686 (zF), 20 September 2001, Rivière Banane (s.s. 12);
HEC 14821, 27 September 2001, Ile Hermitage (s.s. 18).
Ecology. Infralittoral fringe, mostly between branches of dead acroporoid
corals; a single collection of specimens almost completely sunken in the sediment
between Halophila stipulacea in the lagoon, 0.5 m deep.
Distribution. Aldabra Islands, Diego Garcia Atoll, India, Indonesia (Sumba),
Kenya, Maldives, Mauritius (Børgesen, 1940: 11; 1948: 20), Réunion (Payri,
1985: 640), Rodrigues (this paper), Seychelles, Somalia, Tanzania, Thailand.
VALONIACEAE
Valonia C. Agardh
Valonia aegagropila C. Agardh, 1823: 429–430
References: Taylor, 1960: 109–112, pl. 7, figure 6; Jaasund, 1976: 15, figure 29 (as V.
aegagrophila); Magruder and Hunt, 1979: 33, figure 3 p. 32; Tseng, 1984: 270,
pl. 134, figure 3; Moorjani and Simpson, 1988: 16, pl. 30; Allen and Steene, 1994:
21; Littler and Littler, 2000: 338, figure p. 339; Payri et al., 2000: 78, figure p. 79;
Littler and Littler, 2003: 206, top figure p. 207.
Lectotype locality. Venezia, Italy.
Vouchers. HEC 14654 (zF), 19 September 2001, Gravier (s.s. 16); HEC
14794, 25 September 2001, Passe Grand Bassin (s.s. 2).

2976 E. Coppejans et al.
Ecology. Epilithic, collected on pebbles and on a coral head in the infralittoral
fringe.
Distribution. Chagos Archipelago, India, Indonesia, Kenya, Laccadives, Malaysia,
Maldives, Mauritius (Børgesen, 1940: 11–12; 1946: 13; 1948: 21; 1953: 5), Mozambique,
Oman, Pakistan, Réunion (Montagne and Millardet, 1862: 5; Payri, 1985: 640),
Rodrigues (Dickie, 1877a: 7), Seychelles, Somalia, South Africa, Tanzania.
Note. V. aegagropila differs from other Valonia species by its irregular
branching patterns and the small cells (apical cells up to 1600 mm in diameter).
BRYOPSIDALES
BRYOPSIDACEAE
Bryopsis Lamouroux
Key to the species from Rodrigues
1 Plants small, 1–3 cm, plumule oblongate to ovate, 1–3 mm broad and 2–8 mm
long. . . . . . . . . . . . . . . . . . . . . . B. indica
– Plants larger, plumule linear-lanceolate, sometimes bent . . . . . . . . . 2
2 Main axis generally curved, ramuli unilateral or partly distichous, but then the
curvature of the ramuli from the most dense row parallel with the main axis, those
from the sparsely set row incurved . . . . . . . . B. pennata var. secunda
– Main axis mostly straight, ramuli clearly distichous, on two opposite (sometimes
double) rows . . . . . . . . . . . . . . . . . . . . . . 3
3 Plumule not interrupted by bare parts . . . . . . . B. pennata var. pennata
– Plumule interrupted by bare parts without ramuli . . . B. pennata var. leprieurii
*Bryopsis indica A. Gepp and E. Gepp, 1908: 169–170, pl. 22, figures 10, 11
References: Womersley and Bailey, 1970: 271; Moorjani and Simpson, 1988: 12,
pl. 12; Coppejans et al., 1995a: 74, figure 1; Coppejans and Van den heede, 1996:
52, figures 4, 7; Kraft, 2000: 627, figure 41A–C.
Syntype localities. Chagos Archipelago; Coetivy Reef; Mauritius; Sri Lanka.
Voucher. HEC 14609b, 18 September 2001, western part of Cotton Bay (s.s. 13).
Ecology. Epilithic and locally frequent, at about spring low tide level,
exposed to severe surf at low tide. Partly mixed with B. pennata.
Distribution. Bangladesh, Chagos Archipelago, India, Kenya, Maldives,
Mauritius, Rodrigues (this paper), Seychelles, Singapore, Somalia, Sri Lanka,
Tanzania (Coppejans et al., 2000: 66).
*Bryopsis pennata Lamouroux, 1809a: 333 var. pennata
(figure 3)
References: Dawson, 1954: 393, figure 11b; Coppejans and Van den heede, 1996:
52–54, figures 8, 9, 12, 16, 20; Littler and Littler, 2000: 342, figure p. 343; Skelton
and South, 2002: 163, figure 24E; Littler and Littler, 2003: 208, middle figure p. 209.
Type locality. Antilles, West Indies.
Voucher. HEC 14609a (zF) pro parte, 18 September 2001, western part of
Cotton Bay (s.s. 13).

Marine green and brown algae of Rodrigues 2977
Ecology. Epilithic, at about spring low water level, exposed to strong surf.
Distribution. Aldabra Islands, Chagos Archipelago, India, Kenya, Malaysia,
Maldives, Nicobar Islands, Oman, Pakistan, Rodrigues (this paper), Seychelles,
Sri Lanka, Yemen.
Note. Some parts of the collected tufts, dominated by B. pennata var. pennata,
also contain specimens with unilaterally bent branchlets, corresponding to
B. pennata var. secunda, and specimens with bare parts along the rachis (interrupted
plumules), corresponding to B. pennata var. leprieurii. As already stated
previously (Coppejans and Van den heede, 1996: 54), the distinction between
these varieties therefore seems to be artificial.
*Bryopsis pennata Lamouroux var. leprieurii (Kützing) Collins and
Hervey, 1917: 62
(figure 4)
References: Jaasund, 1976: 17, figure 35; Coppejans and Van den heede, 1996:
54–56, figures 10, 13.
Type locality. Cayenne, French Guiana.
Voucher. HEC 14757, 22 September 2001, Grand Baie (s.s. 11).
Ecology. Locally abundant on vertical walls of coral heads that are continuously
exposed to surf.
Distribution. Diego Garcia Atoll, Kenya, Réunion (Payri, 1985: 640), Rodrigues
(this paper), Singapore, Tanzania, Yemen.
Note. Notwithstanding the above-mentioned criticism, this collection was
identified to the varietal level because it is completely composed of specimens
with interrupted plumules.
*Bryopsis pennata Lamouroux var. secunda (Harvey) Collins and Hervey, 1917: 62
(figure 5)
References: Jaasund, 1976: 17, figure 36; Coppejans and Van den heede, 1996: 56,
figures 11, 14; Littler and Littler, 2000: 342, figure p. 343; Payri et al., 2000: 82,
figure p. 83; Littler and Littler, 2003: 208, bottom figure p. 209.
Syntype localities. Key West and Sand Key, Florida, USA.
Voucher. HEC 14796, 25 September 2001, Grand Baie (s.s. 11).
Ecology. Epilithic at 25m.
Distribution. Diego Garcia Atoll, India, Mauritius, Réunion, Rodrigues (this
paper), Singapore, Tanzania, Yemen.
Note. Notwithstanding the above-mentioned criticism, this collection was
identified to the varietal level because it is completely composed of specimens
with branchlets on two rows, incurved to one side of the rachis.
General remarks on the distribution of Bryopsis in the Mascarene Islands
Except for B. pennata var. secunda, the same Bryopsis taxa have been found on
Rodrigues and Mauritius.

2978 E. Coppejans et al.
CAULERPACEAE
Caulerpa Lamouroux
Key to the species from Rodrigues
Prostrate branches are called stolonoids, erect branches assimilators, their main
axis rachis, the compressed parts fronds and the side branchlets ramuli.
1 Assimilators strap-like . . . . . . . . . . . . . . . . . . . 2
– Assimilators not strap-like . . . . . . . . . . . . . . . . . . 3
2 Assimilators rather broad (3–10 mm), fleshy, unbranched or (pseudo-)dichotomously
branched, with almost smooth to regularly short-toothed margin . . C. brachypus
– Assimilators narrow (2 mm), (pseudo-)dichotomously branched, mostly spirally
twisted (but sometimes branched in a single plane); marginal teeth well-marked
and serial . . . . . . . . . . . . . . . . . . . C. serrulata
3 Ramuli either peltate or vesiculate (spherical, clavate or turbinate) . . . . . . 4
– Ramuli filiform or spiny or with pinnate aspect . . . . . . . . . . . 9
4 Ramuli peltate (stalk-like lower portion abruptly expanded into a horizontally spread
structure) . . . . . . . . . . . . . . . . . . . . . . . 5
– Ramuli not peltate but vesicle-like . . . . . . . . . . . . . . . 7
5 Peltate structures singly on the stolonoids . . . . . . . . . . C. peltata
– Peltate structures grouped . . . . . . . . . . . . . . . . . . 6
6 Peltate structures randomly radially arranged around the central rachis . . .
. . . . . . . . . . . . . . . . . . . C. racemosa var. peltata
– Peltate structures bearing other peltate structures at the margin of the circular fronds
or from their central part . . . . . . . . . . . . . . C. numullaria
7 Ramuli densely packed and randomly radially arranged around the central rachis, the
basal ones cylindrical, becoming clavate higher up and pear-shaped at the top of the
assimilators . . . . . . . . . . . . . . C. racemosa var. laetevirens
– All ramuli (sub-)spherical . . . . . . . . . . . . . . . . . . 8
8 Stolonoids thin, elegant, ramuli 1.5 mm in diameter, stalk-like portion of the ramuli
markedly constricted; vesiculate ramuli¡on longitudinal rows . . . C. lentillifera
– Stolonoids fleshy, with a stout habit; assimilators either short (1–2 cm), bearing only a
few ramuli, resulting in a prostrate thallus or longer and bearing numerous ramuli;
spherical part of the ramuli 1–2 mm wide (or more), shortly stipitate . . . .
. . . . . . . . . . . . . . . . . . C. racemosa var. racemosa
9 Assimilators pinnate (ramuli on two opposite, longitudinal rows) . . . . . 10
– Assimilators not pinnate (ramuli on three longitudinal rows or randomly radially
arranged around the central rachis) . . . . . . . . . . . . . . 14
10 Ramuli compressed, sickle-shaped, upwardly curved . . . . . . . . . 11
– Ramuli cylindrical, upwardly curved. . . . . . . . . . . . . . 12
11 Ramuli slightly constricted at the base, with straight parallel sides in the middle part,
upwardly curved and gradually tapering into a spine at the apex; ramuli not
overlapping . . . . . . . . . . . . . . . . . . . C. taxifolia
– Ramuli markedly wider in the middle part, without parallel sides, rather abruptly
tapering into an upwardly curved terminal spine; ramuli frequently touching or even
overlapping in their widest part . . . . . . . . . . . . C. mexicana
12 Total width of the assimilators generally 10–15 mm (rarely down to 7 mm) . .
. . . . . . . . . . . . . . . . . . . . C. sertularioides
– Total width of the assimilators not exceeding 4 mm . . . . . . . . . 13

Marine green and brown algae of Rodrigues 2979
13 Ramuli up to twice as long as the diameter of the rachis . . . . . . .
. . . . . . . . . . . . C. cupressoides var. lycopodium f. disticha
– Ramuli generally three to four (but up to six) times as long as the diameter of the
rachis . . . . . . . . . . . C. cupressoides var. lycopodium f. elegans
14 Ramuli in three longitudinal rows (at least in part of the assimilators) . . .
. . . . . . . . . . . . . . . C. cupressoides var. cupressoides
– Ramuli randomly radially arranged around the central rachis . . . . . . 15
15 Stolon without ramuli; ramuli of the assimilators rather long C. sertularioides f. farlowii
– Stolon also covered by short ramuli; ramuli of assimilators short, resulting in a
spongy aspect . . . . . . . . . . . . . . . . . . . . 16
16 Ramuli unbranched . . . . . . . . . . . . . . . . C. lanuginosa
– Ramuli dichotomously or subdichotomously branched . . . . . C. webbiana
*Caulerpa brachypus Harvey, 1860: 333
(figures 7–13)
References: Weber-van Bosse, 1898: 282–283, pl. 22, figures 3, 4; Jaasund, 1976: 19,
figure 39; Coppejans and Prud’homme van Reine, 1992: 673, figures 1A–C, 7A;
Trono, 1997: 30, figure 17; Littler and Littler, 2000: 358, figure p. 359.
Type locality. Tanega-shima, Kogashima Prefecture, Japan.
Vouchers. HEC 14612, 18 September 2001, western side of Cotton Bay
(s.s. 13); HEC 14656a, HEC 14656b (zF), 19 September 2001, Gravier (s.s. 16);
HEC 14718, 21 September 2001, Petite Butte (s.s. 24); HEC 14769, 25 September
2001, Passe Grand Bassin (s.s. 2); HEC 14867, 30 September 2001, south-western
part of the lagoon (s.s. 31).
Ecology. In pools of the mid- to low intertidal zone and in the subtidal; on
silty-sandy substrate as well as on coral rubble or even coral heads, locally even
in very turbid water and covered by silt.
Distribution. Aldabra Islands, Indonesia, Madagascar, Mauritius (Børgesen,
1946: 36–37, figures 14, 15; 1948: 31–32 (C. brachypus var. mauritiana); 1951:
8–9, figure 3 (C. brachypus var. mauritiana f. exposita)), Mozambique, Rodrigues
(this paper), Seychelles, Somalia, South Africa, Tanzania.
Note. This is the most frequent Caulerpa species on Rodrigues, forming
dense meadows over vast surfaces in different biotopes. Fishermen use it as bait
and it is heavily collected for that purpose. Its morphology is variable in size
and in branching pattern. The assimilators are rather fleshy. Most collections
have simple (or only rarely branched) assimilators that are plain with smooth
margins, approximately 5 cm high. In other populations the blades are very large
(up to 20–25 cm long), repeatedly dichotomously branched, with (partly) dentate
margin. In these specimens, secondary stolons are formed higher up. All intermediates
between those two forms occur. At Pointe Palmiste the large growth
form develops in grooves between bumps of coral rubble, the small growth form
is present on the bumps, just under mean low water mark (most probably
exposed at spring low tide). In one collection the apical parts of the
assimilators are three-winged and dentate, the lower portion being plain and
strap-like.

2980 E. Coppejans et al.
FIGS 7–13. Caulerpa brachypus, variation in the general morphology and margin structure
of the assimilators. (7) Large growth form collected in grooves between bumps of
coral rubble, frequently branching and with secondary stolons (HEC 14867).
(8) Intermediately large growth form with wide assimilators (HEC 14769).
(9) Intermediately large growth form with relatively narrow assimilators (HEC
14656a). (10) Typical specimen with simple or scarcely branched assimilators (HEC
14612). (11) Assimilator with smooth margin (HEC 14612). (12) Assimilator with
coarsely dentate margin (HEC 14656a). (13) Assimilator with densely dentate margin
(HEC 14718). Scale bars: 2 cm (7–10); 1 mm (11–13).
Caulerpa cupressoides (Vahl) C. Agardh, 1817: XXIII var. cupressoides
Note. See note on C. cupressoides var. lycopodium f. disticha.
*Caulerpa cupressoides (Vahl) C. Agardh var. lycopodium Weber-van Bosse
f. disticha Weber-van Bosse, 1898: 327, 338, pl. 27, figure 14
References: Coppejans and Beeckman, 1990: 112–114, figures 3–7; Coppejans, 1992:
389, figure 1b (~ecad lycopodium-disticha); Coppejans and Prud’homme van
Reine, 1992: 673, figures 2C, D, 10A, B (~ecad lycopodium-disticha); Payri et al.,
2000: 90, figure p. 91.

Marine green and brown algae of Rodrigues 2981
Syntype localities. Guadeloupe, West Indies; Florida, USA.
Vouchers. HEC 14625b; 21 September 2001, HEC 14737, HEC 14738, 18
September 2001, western part of Cotton Bay (s.s. 13); HEC 14692 (zS), 20 September
2001, Rivière Banane (s.s. 12); HEC 14770, 25 September 2001, Passe
Grand Bassin (s.s. 2); HEC 14834 (zS), 27 September 2001, Baie de l’Hermitage
(s.s. 22); HEC 14882, 1 October 2001, Totor (s.s. 9).
Ecology. On silty-sandy bottom of intertidal pools as well as in shallow subtidal.
Distribution. India, Rodrigues (this paper), Tanzania.
Note. Caulerpa cupressoides var. cupressoides, with the typical three vertical
rows of spiny branchlets along the whole rachis of the assimilators, has not
been observed on Rodrigues. The majority of the specimens belong to var. lycopodium,
with two opposite rows of these branchlets. One collection contains
assimilators that have opposite rows of branchlets in the basal part of the assimilators
and three rows higher up. This phenomenon has been reported previously
(Coppejans and Prud’homme van Reine, 1992: 676, figure 2B) and casts doubt
on the varietal value. The specimens close to the reef crest have shorter assimilators
that are stiff, creamy green, sometimes with a somewhat recurved rachis.
Those from sheltered areas are longer and more supple, of very different width.
The rachis of the assimilators is generally unbranched, but repeatedly dichotomously
branched specimens have also been collected. In one collection (HEC 14738),
the rachis is more compressed (and wider), tending to C. lessonii Bory de Saint-
Vincent (Coppejans and Prud’homme van Reine, 1992: 692, figure 5). Yet another
collection (HEC 14882) is extremely thin and elegant, with relatively short branchlets.
The latter character excludes its attribution to var. lycopodium f. elegans.
*Caulerpa cupressoides (Vahl) C. Agardh var. lycopodium f. elegans (Crouan and
Crouan) Weber-van Bosse, 1898: 336
(figures 14, 15)
References: Coppejans, 1992: 391, figure 1a (~ecad lycopodium-elegans); Coppejans
and Prud’homme van Reine, 1992: 679, figures 2E, 11A (~ecad lycopodiumelegans);
Kraft, 2000: 598, figure 32E.
Type locality. Guadeloupe, West Indies.
Vouchers. HEC 14691 (zS), 20 September 2001, Rivière Banane (s.s. 12);
HEC 14820a (zS), HEC 14820b, 27 September 2001, Ile Hermitage (s.s. 18).
Ecology. On the sandy bottom of a high intertidal rockpool and just under
spring low tide level.
Distribution. Indonesia (Java and Sumba), Rodrigues (this paper),
Seychelles.
*Caulerpa lanuginosa J. Agardh, 1873: 28
References: Jaasund, 1976: 21, figure 43; Sartoni, 1978: 405, 412–413; Littler and
Littler, 2000: 362, figure p. 363.
Type locality. Key West, Florida, USA.
Vouchers. HEC 14655 (zF), 19 September 2001, Gravier (s.s. 16); HEC
14863, 30 September 2001, south-western lagoon (s.s. 27).
Ecology. On sand or sand-covered rock at about spring low tide level.

2982 E. Coppejans et al.
FIGS 14–18. Caulerpa. (14) Caulerpa cupressoides var. lycopodium f. elegans, small, elegant
specimen (HEC 14691). (15) Caulerpa cupressoides var. lycopodium f. elegans, coarse
specimen with richly branched assimilators (HEC 14820). (16) Caulerpa sertularioides
f. sertularioides, last order branchlets in a single plane (HEC 14739). (17) Caulerpa
sertularioides f. farlowii, last order branchlets in several planes (HEC 14690). (18)
Caulerpa webbiana (HEC 14699). Scale bars: 1 cm.
Distribution. Mozambique, Rodrigues (this paper), Somalia, South Africa, Tanzania.
Note. For a comparison with C. webbiana, see the latter species.
*Caulerpa lentillifera J. Agardh, 1837: 173
References: Jaasund, 1976: 25, figure 49; Coppejans and Meinesz, 1988: 184,
figures 39–41; Moorjani and Simpson, 1988: 13, pl. 13; Coppejans and
Beeckman, 1989: 383, figures 1–3; Coppejans and Prud’homme van Reine,
1992: 690, figures 4E, F, 14A, B; Cribb, 1996: 17, figure p. 16; Huisman, 2000:
253, unnumbered figure; Littler and Littler, 2003: 220, middle figure p. 221.

Marine green and brown algae of Rodrigues 2983
Type locality. Eritrea.
Voucher. HEC 14717, 21 September 2001, Petite Butte (s.s. 24).
Ecology. On a wooden pole, just under low water mark.
Distribution. Australia, India, Indonesia, Kenya, Madagascar, Malaysia,
Maldives, Mauritius (Børgesen, 1953: 9–10), Mozambique, Pakistan, Rodrigues
(this paper), Singapore, Somalia, South Africa, Sri Lanka, Tanzania.
*Caulerpa mexicana Sonder ex Kützing f. exposita (Børgesen) Coppejans comb.
nov.
References: Børgesen, 1954: 8, figures 1, 2; Littler and Littler, 2003: 216, top
figure p. 217; both as Caulerpa crassifolia (C. Agardh) J. Agardh f. exposita
Børgesen.
Type locality. Riambel, near Souillac, Mauritius.
Voucher. HEC 14814, 24 September 2001, Ile aux Fous (s.s. 6).
Ecology. Epilithic on an acroporoid coral under a vertical wall of the reef
slope, 17 m deep.
Distribution. Mauritius, Rodrigues (this paper).
Note. Our specimen completely agrees with the original description by Børgesen
(1954) and the description and illustration by Littler and Littler (2003: 216,
figure p. 217), with short, rather stiff, recurved fronds (‘arched toward the substrate’)
instead of the rather supple, erect plants of typical C. mexicana. Silva
et al. (1996: 826) mention that ‘this taxon (C. crassifolia f. exposita) apparently
lies within the circumscription of C. mexicana but has not yet been transferred
or reduced to synonymy’. In the field we readily identified our specimen as
C. mexicana because of the typical shape of the pinnules, overlapping in the
middle part (and therefore distinct from C. taxifolia). In our notes we added:
‘compact, rather stiff growth form’, which corresponds with Børgesen’s description
of this taxon. For these reasons we transfer C. crassifolia f. exposita to
C. mexicana f. exposita. It should be mentioned, though, that our specimen (at
17 m depth) was not exposed to strong surf, unlike those from Mauritius, but
was very strongly attached to the coral, breaking up during collection.
*Caulerpa nummularia Harvey ex J. Agardh, 1873: 38
(figure 19)
References: Jaasund, 1976: 19, figure 37; Tseng, 1984: 282, pl. 140, figure 1; Cribb,
1996: 17, figure p. 16; Littler and Littler, 2000: 364, figure p. 365; Littler and
Littler, 2003: 224, middle figure p. 225.
Syntype localities. Tonga; Nukahiva, Marquesas Islands.
Voucher. HEC 14633, 18 September 2001, western side of Cotton Bay
(s.s. 13).
Ecology. Epilithic in the subtidal fringe; on horizontal as well as on vertical
substrates.
Distribution. India, Mauritius (Børgesen, 1946: 40), Rodrigues (this paper),
Sri Lanka, Tanzania.
Note. See note on Caulerpa peltata.

2984 E. Coppejans et al.
FIGS 19–24. Chlorophyta. (19) Caulerpa nummularia, proliferating from primary, peltate
assimilator (HEC 14609 p.p.). (20) Rhipidosiphon javensis (HEC 14763). (21) Udotea
sp. (HEC 14759). (22–24) Udotea palmetta (HEC 14817): (22) general morphology of
large, fertile specimen; (23) gametangia growing from the blade surface; (24)
gametangia growing from the blade margin. Scale bars: 2 mm (19, 20); 1 cm (21,
22); 1 mm (23); 500 mm (24).
*Caulerpa peltata Lamouroux, 1809a: 332
References: Tseng, 1984: 282, pl. 140, figure 3; Kraft, 2000: 599, figure 33E, F; Payri
et al., 2000: 92, figures pp. 89, 93; Skelton and South, 2002: 163, figure 25B.
Type locality. Antilles, West Indies.
Vouchers. HEC 14633, 18 September 2001, western side of Cotton Bay
(s.s. 13); HEC 14702 (zS), 20 September 2001, Rivière Banane (s.s. 12).
Ecology. Epilithic in the subtidal fringe; on horizontal as well as on vertical
substrate.
Distribution. Aldabra Islands, Andaman Islands, Australia, Bangladesh, Christmas
Island, Comores, Diego Garcia Atoll, India, Indonesia, Kenya, Laccadives,
Madagascar, Malaysia, Maldives, Mauritius (Dickie, 1874: 197, Børgesen, 1940: 51;
1946: 39–40; 1952: 11; 1953: 9), Mozambique, Nicobar Islands, Oman, Pakistan,
Réunion (Jadin, 1935: 156), Rodrigues (this paper), Seychelles, Singapore, Somalia,
South Africa, Sri Lanka, Tanzania, Thailand, Yemen.

Marine green and brown algae of Rodrigues 2985
Notes. (1) On Rodrigues Caulerpa peltata is abundant on the reef crest, at
about spring low water level, at sites exposed to very strong surf and on wellilluminated
horizontal substrate. Sole peltate branchlets are placed on the wellattached
and intricate, thin stolons. No intermediates were found with C. racemosa
var. laetevirens or var. turbinata. (2) Two other similar morphospecies of Caulerpa
grow on Rodrigues. In the first one the thallus is fleshier (thick stolons and assimilators),
and the rachis of the erect assimilators bears several side branches placed
in three dimensions. In some specimens all branchlets are peltate. We consider
this entity as C. racemosa var. peltata (Coppejans and Beeckman, 1989: 388,
figures 27–29). Sometimes the basal branchlets are cylindrical, becoming clavate
or turbinate in the middle part of the rachis and peltate towards the rachis
apices. We identify this entity as an intermediate between C. racemosa var. laetevirens
and var. peltata. InC. racemosa var. laetevirens s.s. the basal branchlets
are cylindrical, becoming clavate higher up and turbinate at the tips of the
rachis (no peltate branchlets). We also collected C. nummularia, with thin stolons,
peltate branchlets on the stolon (not on a rachis) bearing another peltate
branchlet either on the margin of the disc-shaped part of the branchlet or from
its middle part, resulting in superposed peltate structures. C. nummularia was
found growing together with C. peltata and therefore might be a growth form of
the latter. Molecular research will give more insight into the phylogenetic relationships
of these species and varietal complexes.
*Caulerpa racemosa (Forsskål) J. Agardh, 1873: 35–36
References: Jaasund, 1976: 25, figure 50 (~var. clavifera f. macrophysa); Magruder
and Hunt, 1979: 19, figure 1 p. 18; Tseng, 1984: 282, pl. 140, figure 4 (~var.
clavifera (Turner) Weber-van Bosse); Coppejans and Meinesz, 1988: 191,
figures 22, 23 (~var. clavifera); Coppejans and Beeckman, 1989: 384, figure 4
(~var. clavifera f. macrophysa); Coppejans, 1992: 401, figure 4C, D (~ecad
racemosa); Coppejans and Prud’homme van Reine, 1992: 698, figure 18A, B
(~ecad racemosa); Allen and Steene, 1994: 19, 27; Coppejans et al., 1995a: 78,
figure 7 (~ecad racemosa); Cribb, 1996: 17, figure p. 16 (~var. clavifera); Kraft,
2000: 602, figure 34A–D; Littler and Littler, 2000: 370, figure p. 371; Payri et al.,
2000: 94, figures pp. 89, 95; Littler and Littler, 2003: 226, middle figure p. 227.
Type locality. Suez, Egypt.
Vouchers. HEC 14660, 19 September 2001, Gravier (s.s. 16); HEC 14700, 20
September 2001, Rivière Banane (s.s. 12).
Ecology. Epilithic on the fringing reef; at about spring low tide and exposed
with good tides.
Distribution. Aldabra Islands, Andaman Islands, Australia, Bangladesh,
Burma, Djibouti, India, Indonesia, Kenya, Laccadives, Madagascar, Malaysia,
Maldives, Mauritius (Børgesen, 1940: 51; 1946: 39; 1948: 32; 1949: 14; 1952: 11;
1953: 8), Mozambique, Nicobar Islands, Pakistan, Réunion (Jadin, 1935:
156~Caulerpa clavifera (Turner) C. Agardh; Payri, 1985: 640~Caulerpa racemosa
(Forsskål) J. Agardh var. clavifera (Turner) Weber-van Bosse), Rodrigues (this
paper), Seychelles, Singapore, Somalia, South Africa, Sri Lanka, Tanzania,
Yemen.

2986 E. Coppejans et al.
Note. Recent molecular research clearly indicates that the C. racemosacomplex
is polyphyletic. The distinction on varietal level here is solely based on
the ‘traditional’ morphological characters, which are very variable (see Note 2
with C. peltata).
*Caulerpa racemosa var. laetevirens (Montagne) Weber-van Bosse, 1898: 366,
367, pl. 33, figures 16, 20
References: Coppejans and Beeckman, 1989: 386, figures 21–23; Coppejans and
Prud’homme van Reine, 1992: 693, figure 16A–C; Cribb, 1996: 19, figure p. 18
(as var. occidentalis); Kraft, 2000: 604, figure 34C; Huisman, 2000: 254,
unnumbered figure.
Type locality. Toud Island, Torres Strait, Australia.
Vouchers. HEC 14629, 18 September 2001, western side of Cotton Bay
(s.s. 13); HEC 14661, HEC 14662, 19 September 2001, Gravier (s.s. 16); HEC
14701 (zS, zF), 20 September 2001, Rivière Banane (s.s. 12); HEC 14868,
HEC 14869 (zF), 30 September 2001, south-western lagoon (s.s. 31).
Ecology. Epilithic on the fringing reef, at about spring low water mark, as
well as on the sheltered landward side of the reef, but more frequent on the
surf-exposed seaward side.
Notes. (1) See C. peltata, Note 2. (2) Specimens in some patches have long,
rather supple assimilators; other patches only contain short, rather stiff plants.
Caulerpa racemosa var. peltata (Lamouroux) Eubank in Stephenson, 1944: 349
References: Kraft, 2000: 604, figure 34D; Littler and Littler, 2003: 228, bottom
figure p. 229.
Note. See C. peltata, Note 2.
Caulerpa serrulata (Forsskål) J.Agardh, 1837: 174
References: Jaasund, 1976: 23, figure 48; Magruder and Hunt, 1979: 19, figure 2
p. 18; Tseng, 1984: 284, pl. 141, figure 1; Coppejans and Meinesz, 1988: 191,
figures 25, 26; Moorjani and Simpson, 1988: 13, pl. 16; Coppejans and
Beeckman, 1990: 120, figures 24, 25; Coppejans and Prud’homme van Reine,
1992: 703, figure 20B; Allen and Steene, 1994: 19; Coppejans et al., 1995a: 78,
figures 9, 10; Cribb, 1996: 19, figure p. 18; Huisman, 2000: 257, unnumbered
figure; Littler and Littler, 2000: 372, figure p. 373; Payri et al., 2000: 94, figures
pp. 88, 95; Leliaert et al., 2001: 452, figure 1; Skelton and South, 2002: 164,
figure 24B–D; Littler and Littler, 2003: 230, 232, middle figure p. 231, top
figure p. 233.
Type locality. Mokha, Yemen.
Vouchers. HEC 14689, 20 September 2001, Rivière Banane (s.s. 12); HEC
14772, 25 September 2001, Passe Grand Bassin (s.s. 2).
Ecology. On sandy substrate in a shallow intertidal rock pool as well as on
silty substrate in the lagoon, between coral heads from low water mark down to
0.5 m.

Marine green and brown algae of Rodrigues 2987
Distribution. Aldabra Islands, Andaman Islands, Chagos Archipelago,
Comores, Diego Garcia Atoll, Djibouti, India, Indonesia, Kenya, Laccadives,
Madagascar, Malaysia, Maldives, Mauritius (Børgesen, 1940: 50; 1946: 38; 1949:
13–14; 1953: 8), Mozambique, Nicobar Islands, Réunion (Jadin, 1935: 156~Caulerpa
freycinetii C. Agardh; Payri, 1985: 640), Rodrigues (Dickie, 1877b: 7), Seychelles,
Singapore, Somalia, Tanzania, Yemen.
Note. One collection has the typically spirally twisted assimilators, whereas in
the other collection they are spread in a single plane. Weber-van Bosse (1898:
313–314) distinguishes varieties based on this character. As we previously
observed that the degree of twisting differs gradually (Coppejans and
Prud’homme van Reine, 1992: 704) we do not distinguish both growth forms on
a varietal level. The straps of the latter collection are not markedly toothed but
merely show a sinusoidal margin.
Caulerpa sertularioides (S. Gmelin) Howe, 1905: 576
(figure 16)
References: Jaasund, 1976: 23, figure 47; Magruder and Hunt, 1979: 19, figure 3
p. 18; Tseng, 1984: 284, pl. 141, figure 2; Coppejans and Meinesz, 1988: 192,
figure 29; Moorjani and Simpson, 1988: 13, pl. 17; Coppejans and Beeckman,
1990: 120, figures 26, 27; Coppejans and Prud’homme van Reine, 1992: 704,
figure 21A; Coppejans et al., 1995a: 80, figure 8; Cribb, 1996: 21, figure p. 20; De
Clerck and Coppejans, 1996: 208, figures 2, 3, 11; Huisman, 2000: 258,
unnumbered figure; Littler and Littler, 2000: 374, figure p. 375; Payri et al., 2000:
96, figures pp. 88, 97; Littler and Littler, 2003: 232, middle figure p. 233.
Type locality. ‘In coralliis americanis’.
Vouchers. HEC 14739, 21 September 2001, Petite Butte (s.s. 24); HEC 14754,
22 September 2001, Grand Baie (s.s. 11); HEC 14773 (zS): 25 September 2001,
Passe Grand Bassin (s.s. 2).
Ecology. On (silty) sand and on sand-covered rock at about low water mark,
in a mid-littoral pool and in the lagoon at 0.5 m depth at low tide.
Distribution. Andaman Islands, Australia, Bahrain, Burma, Djibouti, India,
Indonesia, Iran, Kenya, Kuwait, Laccadives, Madagascar, Malaysia, Maldives,
Mauritius (Børgesen, 1940: 49–50), Mozambique, Nicobar Islands, Pakistan,
Réunion (Payri, 1985: 640), Rodrigues (Dickie, 1877b: 7, as C. plumaris (Forsskål)
C. Agardh), Saudi Arabia, Seychelles, Singapore, Somalia, South Africa,
Sri Lanka, Tanzania, Thailand, Yemen.
Note. Some specimens only have assimilators of the forma sertularioides
type, with branchlets on two opposite rows in a single plan. Other stolons bear
this type together with assimilators with two opposite, unorderly arranged, longitudinal
groups of ramuli. Still other collections bear both typical and farlowii
type (with branchlets all around the rachis) assimilators. Finally, some stolons
exclusively bear the latter assimilator type. They all occur in the same or in very
similar habitats. These field observations indicate that the assignment of some
specimens to one of the forms is difficult, especially when two growth forms
occur on the same stolon. It is unclear which environmental factor induces the
development of one of these morphologies.

2988 E. Coppejans et al.
*Caulerpa sertularioides (Gmelin) Howe f. farlowii (Weber-van Bosse) Børgesen,
1907: 365–366, figure 11
(figure 17)
References: Weber-van Bosse, 1898: 294–296, pl. 24, figures 4–6; De Clerck and
Coppejans, 1996: 208, figures 4, 12; Littler and Littler, 2000: 374, figure p. 375.
Syntype localities. Florida, USA; Ilhas do Cabo Verde; Flores, Indonesia.
Vouchers. HEC 14690, 20 September 2001, Rivière Banane (s.s. 12); HEC
14753, 22 September 2001, Grand Baie (s.s. 11).
Ecology. Sandy substrate in a high intertidal rock pool and between midintertidal
sand bumps.
Distribution. Abu Dhabi, Bahrain, Indonesia, Mauritius (Børgesen, 1940: 50),
Rodrigues (this paper), Saudi Arabia, Seychelles.
Note. See note on C. sertularioides.
*Caulerpa taxifolia (Vahl) C. Agardh, 1817: xxii
References: Jaasund, 1976: 23, figure 46; Magruder and Hunt, 1979: 21, figure 1
p. 20; Tseng, 1984: 284, pl. 141, figure 3; Coppejans and Beeckman, 1990: 122,
figures 36–39; Coppejans, 1992: 406, figure 8A, B; Coppejans and Prud’homme
van Reine, 1992: 706, figures 6B, 22B; Allen and Steene, 1994: 19; Coppejans
et al., 1995a: 80, figure 11; Cribb, 1996: 21, figure p. 20; Huisman, 2000: 259,
unnumbered figure; Kraft, 2000: 604, figures 34E, 35A; Littler and Littler, 2000:
376, figure p. 377; Payri et al., 2000: 98, figures pp. 88, 99; Leliaert et al., 2001:
452, figure 2.
Type locality. St Croix, Virgin Islands.
Vouchers. HEC 14716, 21 September 2001, Petite Butte (s.s. 24); HEC 14767,
HEC 14768, 25 September 2001, Passe Grand Bassin (s.s. 2).
Ecology. On a coral head just under low water mark and on a silty bottom
between coral heads in very turbid water, from low water mark down to 0.5 m
deep.
Distribution. Aldabra Islands, Andaman Islands, Bangladesh, India, Indonesia,
Kenya, Laccadives, Madagascar, Malaysia, Maldives, Mauritius (Ballesteros, 1994:
543), Nicobar Islands, Pakistan, Rodrigues (this paper), Seychelles, Singapore, South
Africa, Sri Lanka, Tanzania, Yemen.
Note. The assimilators of some specimens have typically two opposite rows
of branchlets along the rachis; others have several longitudinal rows of branchlets.
Some stolons bear both types of assimilators.
*Caulerpa webbiana Montagne, 1837: 354
(figure 18)
References: Sartoni, 1978: 410–413; Allen and Steene, 1994: 19; Kraft, 2000: 605,
figure 35A–D; Littler and Littler, 2000: 378, figure p. 379; Payri et al., 2000: 100,
figures pp. 88, 101.
Type locality. Arrecife, Lanzarote, Canary Islands.
Vouchers. HEC 14615, 18 September 2001, western side of Cotton Bay
(s.s. 13); HEC 14699 (zS), 20 September 2001, Rivière Banane (s.s. 12).

Marine green and brown algae of Rodrigues 2989
Ecology. Locally abundant at about low water level, epilithic on horizontal
coral substrate.
Distribution. Madagascar, Mauritius (Børgesen, 1940: 45), Mozambique, Réunion
(Payri, 1985: 640), Rodrigues (this paper), Seychelles, Somalia, South Africa.
Note. C. webbiana is morphologically very similar to C. lanuginosa. Both species
can be easily distinguished by the morphology of the branchlets on the
rachis of the assimilators: C. lanuginosa has unbranched branchlets, C. webbiana
has bifurcate ramuli.
Unchecked data from literature
Caulerpa cupressoides (Vahl) C. Agardh var. ericifolia (Turner) Weber-van Bosse,
1898: 335
Recorded by Dickie (1877a~Caulerpa ericifolia (Turner) C. Agardh).
Caulerpa cupressoides (Vahl) C. Agardh var. mamillosa (Montagne) Weber-van
Bosse, 1898: 332, 333, pl. 28, figure 6 (‘forma typica’).
Recorded by Dickie (1877a~Caulerpa mamillosa Montagne).
Caulerpa serrulata (Forsskål) J. Agardh var. boryana (J. Agardh) Gilbert,
1942: 15
Recorded by Dickie (1877a~Caulerpa boryana J. Agardh).
General remarks on the distribution of Caulerpa in the Mascarene Islands
Caulerpa scalpelliformis (Brown ex Turner) C. Agardh, C. urvilleana Montagne
and C. fastigiata Montagne have been mentioned by Børgesen (1940) from
Mauritius, but were not collected on Rodrigues. Caulerpa lanuginosa, C.
nummularia and C. taxifolia, on the other hand, were observed on Rodrigues
and have not been listed for Mauritius.
Caulerpella Prud’homme van Reine and Lokhorst
*Caulerpella ambigua (Okamura) Prud’homme van Reine and Lokhorst, 1992: 114
References: Lawson and John, 1987: 88, pl. 8, figure 1 (~Caulerpa ambigua
Okamura); Prud’homme van Reine and Lokhorst, 1992: 114; Kraft, 2000: 608,
figure 35F, G; Skelton and South, 2002: 164, figure 25A.
Type locality. Ogasawara-gunto (Bonin Islands), Japan.
Voucher. HEC 14810c, 26 September 2001, Chaland (s.s. 8).
Ecology. Epilithic at 12 m depth, in algal turf, mixed with numerous other
small algae.
Distribution. Maldives, Mauritius (Børgesen, 1949: 6–12, figures 1, 2, as Caulerpa
vickersiae Børgesen), Mozambique, Pakistan, Réunion (Payri, 1985: 640, as
Caulerpa vickersiae), Rodrigues (this paper), Seychelles, South Africa, Tanzania
(Coppejans et al., 2000: 68), Thailand.
Note. Molecular research based on chloroplast tufA gene sequences (Famà
et al., 2002) indicates a high genetic divergence between Caulerpella ambigua and
all Caulerpa species, supporting the taxonomic distinction of Caulerpella as proposed
by Prud’homme van Reine and Lokhorst (1992).

2990 E. Coppejans et al.
CODIACEAE
Codium Stackhouse
Key to the species from Rodrigues
1 Thallus prostrate, composed of irregular lobes, not of cylindrical branches . . . 2
– Thallus dichotomously branched, prostrate or erect, composed of cylindrical or
slightly compressed branches . . . . . . . . . . . . . . . . . 4
2 Utricles 1400–2000 mm long . . . . . . . . . . . . . . C. spongiosum
– Utricles shorter than 1300 mm . . . . . . . . . . . . . . . . . 3
3 Inconspicuous primary utricles up to 700 mm long, bearing a maximum of five
secondary utricles. . . . . . . . . . . . . . . . . . C. lucasii
– Conspicuous primary utricles 700–1270 mm long, bearing up to 10 secondary
utricles . . . . . . . . . . . . . . . . . . . . C. arabicum
4 Thallus repent, attached to the substrate at several places, branches intricate and
anastomosing . . . . . . . . . . . . . . . . . . C. prostratum
– Thallus erect, attached to the substrate at a single point, branches not anastomosing 5
5 Branching irregular, divaricately dichotomous, branches more or less terete C. pocockiae
– Branching regular, dichotomous, branches partly compressed, partly terete . . . 6
6 Interdichotomies terete, 3–6 mm broad, dichotomies compressed, 8–12 mm broad .
. . . . . . . . . . . . . . . . . . . . . . . C. duthieae
– Lower part of the thallus compressed, upper part terete, branches 1–4 mm in
diameter . . . . . . . . . . . . . . . . . . . C. extricatum
Codium arabicum Kützing, 1856: 35, pl. 100, figure II
References: Jaasund, 1976: 33, figure 66; Magruder and Hunt, 1979: 25, figure 1
p. 24; Tseng, 1984: 296, pl. 147, figure 2; Coppejans et al., 1995a: 82, figure 16;
Van den heede and Coppejans, 1996: 390–392, figures 1, 5, 7; Kraft, 2000: 588,
figure 31A; Payri et al., 2000: 102, figure p. 103; Littler and Littler, 2003: 210,
bottom figure p. 211.
Type locality. Tor, Sinai Peninsula, Egypt.
Voucher. HEC 14667 (zF), 19 September 2001, Gravier (s.s. 16).
Ecology. Epilithic on vertical walls of crevices in the fringing reef, at about
spring low tide level.
Distribution. India, Indonesia, Kenya, Laccadives, Madagascar, Malaysia,
Maldives, Mauritius (Børgesen, 1940: 61–68, figures 19–22; 1946: 45–46; 1948:
35–36, figure 16), Mozambique, Nicobar Islands, Oman, Pakistan, Réunion
(Payri, 1985: 640), Rodrigues (Dickie, 1877a (as C. adhaerens C. Agardh): 7),
Seychelles, Singapore, Sri Lanka, Tanzania, Thailand.
*Codium duthieae P. Silva, in Silva and Womersley, 1956: 275–277, figure 10, pl. 1,
figure 2
Reference: Van den heede and Coppejans, 1996: 394–397, figures 3, 9.
Type locality. Strandfontein, False Bay, Cape Province, South Africa.
Voucher. HEC 14747 (zF), 22 September 2001, Grand Baie (s.s. 11).
Ecology. Epilithic, just under spring low water, on the sheltered lagoon side
of the reef.

Marine green and brown algae of Rodrigues 2991
Distribution. Australia, Kenya, Mozambique, Rodrigues (this paper), South Africa.
*Codium extricatum P. Silva, 1959: 145–147, figure 17, pls XIII, XIV
References: Simons, 1977: 21, figure 37; Van den heede and Coppejans, 1996: 398,
figures 10, 15.
Type locality. Mouth of Qolora River, Cape Province, South Africa.
Voucher. HEC 14663 (zF), 19 September 2001, Gravier (s.s. 16).
Ecology. Shallow back reef rock pool; just under spring low water mark.
Distribution. Kenya, Rodrigues (this paper), South Africa, Tanzania (Coppejans
et al., 2000: 68).
*Codium lucasii Setchell, in Lucas, 1935: 200–202, figure 3
Reference: Van den heede and Coppejans, 1996: 402–404, figures 12, 17.
Type locality. Bondi, New South Wales, Australia.
Voucher. HEC 14623 (zF), 18 September 2001, western side of Cotton Bay
(s.s. 13).
Ecology. Abundant from mid-intertidal down to extreme low tide level.
Distribution. Australia, Kenya, Mozambique, Rodrigues (this paper), South
Africa, Tanzania (Coppejans et al., 2000: 70).
Note. Codium lucasii is similar to C. mozambiquense P. Silva, but the utricles
of the latter present an apical depression (Silva, 1959: 109). The former also has
similarities with C. spongiosum with which it grows together, but the thalli of this
species are lighter green, more bullose, can easily be squashed between the fingers
(C. lucasii is very tough) and have large utricles (visible with the naked eye).
*Codium pocockiae P. Silva, 1959: 138–140, figure 14, pl. XII:b
Reference: Van den heede and Coppejans, 1996: 405, figures 13, 19.
Type locality. Port St Johns, Transkei, South Africa.
Vouchers. HEC 14735, 21 September 2001, western side of Cotton Bay
(s.s. 13); HEC 14748 (zF), 22 September 2001, Grand Baie (s.s. 11).
Ecology. Epilithic or on sand-covered rock in shallow sublittoral sites, on the
sheltered side of the fringing reef.
Distribution. Kenya, Mozambique, Rodrigues (this paper), South Africa,
Tanzania (Coppejans et al., 2000: 70).
*Codium prostratum Levring, 1938: 16–17, figure 8A–D, pl. IV, figure 11
References: Van den heede and Coppejans, 1996: 405–406, figures 20–23, 24; Littler
and Littler, 2003: 214, top figure p. 215.
Type locality. Isipingo Beach, near Durban, South Africa.
Voucher. HEC 14626 (zF), 18 September 2001, western side of Cotton Bay
(s.s. 13).
Ecology. Epilithic, from mid-intertidal down to spring low water mark.

2992 E. Coppejans et al.
Distribution. Kenya, Mozambique, Mauritius (Børgesen, 1940: 70–72, figures 24,
25~C. vaughanii Børgesen; 1946: 53–56, figures 23, 24~C. vaughanii), Réunion
(Payri, 1985: 640), Rodrigues (this paper), South Africa.
*Codium spongiosum Harvey, 1855: 565
References: Børgesen, 1946, 46–49, figure 18 (as C. mauritianum (Børgesen)
Børgesen); Cribb, 1996: 27, figure p. 16; Kraft, 2000: 588, figure 28B, C.
Lectotype locality. King George Sound, Western Australia.
Voucher. HEC 14622 (zF), 18 September 2001, western side of Cotton Bay
(s.s. 13).
Ecology. Extremely abundant, with large biomass, from mid-intertidal down
to spring low tide level. Frequently growing together with C. lucasii.
Distribution. Australia, Mozambique, Mauritius (Børgesen, 1940: 68–70,
figure 23; 1946: 46–49, figure 18), Rodrigues (this paper), South Africa.
Note. See C. lucasii. This species is abundant at several locations but has
been collected only once.
General remarks on the distribution of Codium in the Mascarene Islands
Silva (1959) thoroughly studied the genus Codium from South Africa. Specimens
from Kenya, Tanzania and the Seychelles were more recently examined by Van den
heede and Coppejans (1996).
Codium pocockiae and C. extricatum were collected on Rodrigues but have not
been mentioned for Mauritius; C. geppiorum, C. bartletii, C. tomentosum and C.
tenue are cited from Mauritius by Børgesen (1948) but were not observed on
Rodrigues.
Unchecked data from literature
Codium tomentosum Stackhouse, 1797: xxiv
Mentioned by Dickie (1877a) but not among our recent collection.
According to Silva et al. (1996) this species, as circumscribed by Silva (1955:
569–576), is restricted to Atlantic Europe and North Africa. In general, however,
the name has been applied to any terete, dichotomously branched form.
UDOTEACEAE
Avrainvillea Decaisne
*Avrainvillea amadelpha (Montagne) A. Gepp and E. Gepp, 1908: 178–179,
pl. 23, figure 20; pl. 24, figures 21, 22
References: Gepp and Gepp, 1911: 42–44, figures 112–113; Olsen-Stojkovich, 1985:
36–38, figure 19; Coppejans and Prud’homme van Reine, 1989a: 121, pl. 1,
figures 1–17; Coppejans et al., 1995a: 88, figure 29; Littler and Littler, 2003: 236,
bottom figure p. 237.
Type locality. Agalega Islands (Mauritius, approximately 1000 km N of the
main island).
Vouchers. HEC 14634, 18 September 2001, western side of Cotton Bay
(s.s. 13); HEC 14698 (zF, zS), 20 September 2001, Rivière Banane (s.s. 12);
HEC 14819, 27 September 2001, Ile Hermitage (s.s. 18).

Marine green and brown algae of Rodrigues 2993
Ecology. Epilithic on dead coral, at about spring low tide level and in sublittoral,
at 2 m depth in a tide channel.
Distribution. Bahrain, Chagos Archipelago, Djibouti, India, Kenya, Kuwait,
Mauritius (Børgesen, 1940: 54; 1948: 33–34, figures 14–15; 1953: 10), Réunion
(Payri, 1985: 640), Rodrigues (this paper), Saudi Arabia, Seychelles, Singapore,
Tanzania.
Boodleopsis Gepp and Gepp
*Boodleopsis pusilla (Collins) Taylor, Joly and Bernatowicz, 1953: 105–106
References: Cribb, 1954: 31, pl. 1, figure 5; Isaac and Chamberlain, 1958: 124,
126–127, figure 2; Coppejans and van den Heede, 1996: 49–50, figures 1, 5;
Littler and Littler, 2000: 394, figure p. 395; Leliaert et al., 2001: 455,
figures 17–21.
Type locality. West Indies.
Voucher. HEC 14646 (zF), 19 September 2001, Gravier (s.s. 16).
Ecology. On sand-covered rock under the overhanging limestone cliff wall
with Bostrychietum; supralittoral fringe.
Distribution. Aldabra Islands, Kenya, Mozambique, Pakistan, Rodrigues (this
paper), Seychelles, Tanzania.
Halimeda Lamouroux
Key to the species from Rodrigues
1 Plants fleshy and erect; segments weakly calcified, supple . . . . . H. discoidea
– Plants forming cushion-like structures; segments strongly calcified, brittle . H. opuntia
*Halimeda discoidea Decaisne, 1842: 102
References: Jaasund, 1976: 31, figure 62; Magruder and Hunt, 1979: figure 1 p. 28;
Hillis-Colinvaux, 1980: 136–139, figure 41; Tseng, 1984: 288, pl. 143, figure 2;
Coppejans et al., 1995a: 85, figure 22; Cribb, 1996: 31, figure p. 30; Littler and
Littler, 2000: 400, figure p. 401; Payri et al., 2000: 108, figures pp. 106, 109;
Littler and Littler, 2003: 244, middle figure p. 245.
Type locality. True provenance not known.
Vouchers. HEC 14602, 18 September 2001, western side of Cotton Bay
(s.s. 13); HEC 14818 (zA), 27 September 2001, Ile Hermitage (s.s. 18).
Ecology. Covering vast surfaces of horizontal hard substrate in mid- and low
intertidal of the sheltered (landward) side of the fringing reef. Largely exposed at
spring low tide. One collection from the silty slope of a tide channel, at 10 m depth.
Distribution. Amirante Islands, Andaman Islands, Bangladesh, Chagos
Archipelago, Djibouti, India, Indonesia, Kenya, Madagascar, Maldives, Mauritius
(Ballesteros, 1994: 541, 543–544), Mozambique, Nicobar Islands, Réunion (Payri, 1985:
640), Rodrigues (this paper), Singapore, Somalia, Sri Lanka, Tanzania, Thailand.
Note. See the general remarks on Halimeda below.
Halimeda opuntia (Linnaeus) Lamouroux, 1816: 308
References: Jaasund, 1976: 33, figure 65; Magruder and Hunt, 1979: 29, figure 2

2994 E. Coppejans et al.
p. 28; Hillis-Colinvaux, 1980: 110–112, figures 19, 51, 92; Tseng, 1984: 290,
pl. 144, figure 2; Moorjani and Simpson, 1988: 15, pl. 26, right; Allen and Steene,
1994: 21; Coppejans et al., 1995a: 86, figure 27; Cribb, 1996: 33, figure p. 32;
Littler and Littler, 2000: 406, figure p. 407; Payri et al., 2000: 114, figures
pp. 106, 115; Skelton and South, 2002: 165, figure 25 C, D; Littler and Littler,
2003: 252, top figure p. 253.
Lectotype locality. Jamaica.
Voucher. HEC 14736, 21 September 2001, western side of Cotton Bay (s.s. 13).
Ecology. On sand-covered rock substratum just above spring low water
mark, sheltered side of the fringing reef.
Distribution. Aldabra Islands, Amirante Islands, Andaman Islands, Bangladesh,
Burma, Cargados Carajos, Chagos Archipelago, Comores, Diego Garcia Atoll,
Djibouti, India, Indonesia, Kenya, Laccadives, Madagascar, Malaysia, Maldives,
Mauritius (Børgesen, 1940: 61; 1946: 43), Mozambique, Nicobar Islands, Réunion
(Jadin, 1935: 157), Rodrigues (Dickie, 1877a: 7), Saya de Malha Bank, Seychelles,
Singapore, Somalia, Sri Lanka, Tanzania, Thailand.
General remarks on Halimeda and its distribution in the Mascarene Islands
Halimeda opuntia has been collected on both Mauritius and Rodrigues.
Børgesen (1940: 60–61) mentions H. incrassata (Ellis) Lamouroux and H. tuna (Ellis
and Solander) Lamouroux from Mauritius. The former was not found on
Rodrigues. The latter can be expected to be a misidentification of H. discoidea:
morphologically both species are very similar, but anatomically they can be
separated. H. discoidea is characterized by two layers of utricles, the inner layer
being composed of large utricles, the peripheral layer of small utricles. H. tuna
generally shows three layers of utricles of similar size. A phylogeny of the genus
based on nuclear ribosomal DNA and ITS sequences (Kooistra, in press) reveals
that Indo-Pacific specimens confirm Hillis-Colinvaux’s (1980) description of H. tuna
falling within the clade of Indo-Pacific H. discoidea specimens. Thus, Indo-Pacific
H. tuna and Indo-Pacific H. discoidea are conspecific.
Unchecked data from literature
Halimeda tuna (Ellis and Solander) Lamouroux, 1816: 309
Mentioned by Dickie (1877a). See the general remarks on Halimeda.
Rhipidosiphon Montagne
*Rhipidosiphon javensis Montagne, 1842: 15
(figure 20)
References: Jaasund, 1976: 29, figure 60; Tseng, 1984: 294, pl. 146, figure 2
(~Udotea javensis (Montagne) A. Gepp and E. Gepp); Coppejans and
Prud’homme van Reine, 1989a: 139, pl. 10, figures 3–9 (~Udotea javensis);
Littler and Littler, 1990: 33–36, figures 6–11; Payri et al., 2000: 120, figure p. 121;
Coppejans et al., 2001: 422, figures 32–34; Littler and Littler, 2003: 254, middle
figure p. 255.
Type locality. Leiden Island, near Jakarta, Java, Indonesia.

Marine green and brown algae of Rodrigues 2995
Vouchers. HEC 14714, 20 September 2001 and HEC 14880, 1 October 2001,
Totor (s.s. 9); HEC 14763 (zF), 24 September 2001, Ile aux Fous (s.s. 6).
Ecology. Epilithic between branches of dead acroporid coral, in the sublittoral,
between 5 and 18 m depth.
Distribution. Comores, India, Indonesia, Kenya (Coppejans et al., 2000: 75),
Malaysia, Maldives, Mauritius (Børgesen, 1954: 9), Mozambique, Réunion
(Payri, 1985: 640), Rodrigues (this paper), Seychelles, Singapore, Somalia, South
Africa, Sri Lanka, Tanzania, Thailand.
Udotea Lamouroux
Key to the species from Rodrigues
The blade-like part is called flabellum. It is composed of radially arranged
contiguous filaments (or siphons), generally bearing outgrowths or appendages.
1 Filaments of the flabellum with short, simple or bifid to trifid, acute appendages . .
. . . . . . . . . . . . . . . . . . . . . . U. palmetta
– Filaments of the flabellum with long, elaborate, ¡ peltately arranged appendages,
forming a cortex covering the longitudinal filaments . . . . . . . Udotea sp.
*Udotea palmetta Decaisne, 1842: 105
(figures 22–24)
References: Gepp and Gepp, 1911: 108–110, 122–124, pl. 1, figure 11; Jaasund,
1976: 29, figure 58.
Type locality. Not specified.
Vouchers. HEC 14715 (zF), 21 September 2001, Petite Butte (s.s. 23); HEC
14775 (zF), 25 September 2001, Passe Grand Bassin (s.s. 2); HEC 14817 (zF),
27 September 2001, Ile Hermitage (s.s. 18).
Ecology. Mostly on silty sand bottom of the subtidal, from low water mark
down to 0.5 m deep.
Distribution. Amirante Islands, Cargados Carajos, Mauritius (Børgesen, 1940:
59; 1948: 34–35), Persian Gulf, Rodrigues (this paper), Seychelles, Tanzania, Yemen.
Notes. (1) Udotea palmetta is morphologically very similar to U. indica A.
Gepp and E. Gepp. Anatomically they are distinguished by the morphology of
the lateral appendages of the flabellum filaments. These are blunt in the latter
and acute in the former. In U. orientalis these filaments have no appendages at
all. (2) One collection (HEC 14817) is fertile and carries numerous dark green
gametocysts in the middle (figure 23) and marginal (figure 24) parts of the whitish flabellum.
(3) The fully grown specimens are very large when compared to those from
Kenya and Tanzania, but they still agree with the original description. The stipe is
up to 4 cm long, the flabellum 10 (but up to 15) cm long and 14 cm broad.
*Udotea sp.
(figure 21)
Voucher. HEC 14759 (zF), 24 September 2001, Grand Baie (s.s. 10).
Ecology. Only one population of this species was observed. Thalli grew on
coral fragments along the sandy-silty slope of a tide channel, at 15 m depth.
Note. Morphologically similar to U. orientalis A. Gepp and E. Gepp, with
auriculate flabellum, the entire plant being 2.5–4 cm high and the flabellum

2996 E. Coppejans et al.
3–3.5 cm wide. Blade siphons covered by a dense cortex formed by longly
stalked appendages; the apical, peltately arranged parts of these pseudodichotomously
to sympodially branched, with rounded tips. Almost uncalcified and
spongy. Most probably a species new to science.
General remarks on the distribution of Udotea in the Mascarene Islands
Two stout, strongly calcified species that have been mentioned from Mauritius
were not collected on Rodrigues: U. argentea Zanardini (Børgesen, 1940: 60) and U.
flabellum (Ellis and Solander) Howe (Børgesen, 1946: 42–43).
DASYCLADALES
DASYCLADACEAE
Neomeris Lamouroux
Key to the species from Rodrigues
1 Base of the thallus showing discontinuous annular rings . . . . . N. annulata
– No such basal annular rings . . . . . . . . . . . . . N. bilimbata
*Neomeris annulata Dickie, 1874: 198
References: Valet, 1969: 591–595, pl. 15, figure 5, pl. 34, figure 5; Coppejans and
Prud’homme van Reine, 1989b: 127, figures 44–48; Berger and Kaever, 1992:
106–107, figure 3.35a; Littler and Littler, 2000: 438, figure p. 439; Leliaert et al.,
2001: 457, figure 22; Skelton and South, 2002: 166, figure 26C; Littler and
Littler, 2003: 262, top figure p. 263.
Type locality. Mauritius.
Vouchers. HEC 14640, 18 September 2001, western side of Cotton Bay
(s.s. 13); HEC 14693, 20 September 2001, Rivière Banane (s.s. 12); HEC 14790
(zF) and HEC 14793, 25 September 2001, Passe Grand Bassin (s.s. 4); HEC
14853, 25 September 2001, Grand Paté (s.s. 7); HEC 14854, 29 September 2001,
Baie de l’Hermitage (s.s. 22).
Ecology. Epilithic on coral fragments in middle and low intertidal as well as
in the subtidal down to 15 m depth.
Distribution. Aldabra Islands, Chagos Archipelago, Comores, India, Indonesia,
Kenya (Coppejans et al., 2000: 77), Laccadives, Madagascar, Maldives, Mauritius
(Børgesen, 1940: 43; 1949: 5–6), Réunion (Payri, 1985: 640), Rodrigues (this paper),
Seychelles, Singapore, Sri Lanka, Tanzania.
*Neomeris bilimbata Koster, 1937: 221–223, pl. XV, figures 1, 4, 5
References: Valet, 1969: 599, pl. 3, figures 1, 2, pl. 35, figure 6, pl. 42, figures 13, 15,
16; Coppejans and Prud’homme van Reine, 1989b: 127, figures 49–62.
Type locality. Itu Aba, Tizard Bank, South China Sea.
Voucher. HEC 14665 (zF), 19 September 2001, Gravier (s.s. 16).
Ecology. On a coral fragment in a crevice of the fringing reef, low intertidal.
Distribution. Rodrigues (this paper), Seychelles, Singapore.
Note. The gametangia of these specimens are ellipsoid, 1606120 mm, the
apices of the primary branchlets are rounded or laterally flattened. The cellulose

Marine green and brown algae of Rodrigues 2997
plug between the top of the primary branch and the pedicel of the gametangium
is disc-like. There are no calcified lamellae, as in N. dumetosa, nor trifurcate
apices of the primary branches, as in N. vanbosseae, two species frequently mentioned
from the western Indian Ocean. This collection fully agrees with our
description and illustrations (Coppejans and Prud’homme van Reine, 1989b) of
material from Indonesia.
General remarks on the distribution of Neomeris in the Mascarene Islands
Neomeris annulata is present on both Mauritius and Rodrigues. N. bilimbata
has not been recorded from Mauritius and N. van-bosseae Howe, mentioned
from the former island by Børgesen (1946: 31–32), was not collected on the
latter.
POLYPHYSACEAE
Acetabularia Lamouroux
Key to the species from Rodrigues
1 Fertile rays of the discs laterally attached to each other, with straight outer (apical)
margin . . . . . . . . . . . . . . . . . . . . A. calyculus
– Fertile rays of the discs free from each other, with rounded outer (apical) margin A. clavata
*Acetabularia calyculus Lamouroux, in Quoy and Gaimard, 1824: 621, pl. 90,
figures 6, 7
References: Valet, 1969: 605–607, 517–618, pl. 44, figures 7–9; Tseng, 1984: 268,
pl. 133, figure 3; Berger and Kaever, 1992: 128, 154, figures 3.67, 3.68; Kraft,
2000: 630, figure 42A.
Type locality. Shark Bay, Western Australia.
Voucher. HEC 14792, 25 September 2001, Passe Grand Bassin (s.s. 4).
Ecology. Only two specimens were found, which were growing on a subtidal
coral fragment at 1 m depth.
Distribution. Andaman Islands, Nicobar Islands, Australia, Bahrain, Bangladesh,
India, Kenya, Kuwait, Mauritius (Børgesen, 1946: 33), Mozambique,
Rodrigues (this paper), Saudi Arabia, South Africa.
*Acetabularia clavata Yamada, 1934: 57–59, figures 14, 25
Reference: Valet, 1969: 605–607, 620–621, pl. 12, figures 1, 3–6, pl. 19, figure 1,
pl. 20, figures 3, 8, pl. 22, figure 3, pl. 23, figure 1, pl. 30, figure 7, pl. 38, figure 2,
pl. 45, figures 1–4.
Type locality. Tomari, Okinawa-gunto, Ryukyu-retto, Japan.
Voucher. HEC 14845 (zF), 29 September 2001, Grand Paté (s.s. 7).
Ecology. In large numbers on a dead coral fragment in a gulley between
coral heads, 15 m deep.
Distribution. Comores, Kenya, Mauritius (Segonzac, 1983: table 1; 1984: 102,
table 1), Rodrigues (this paper), Seychelles, Tanzania, Thailand.

2998 E. Coppejans et al.
General remarks on the distribution of Acetabularia in the Mascarene Islands
Acetabularia calyculus Lamouroux occurs on both Mauritius and Rodrigues.
A. clavata has not been mentioned for Mauritius but Børgesen (1940: 44) reports
A. parvula Solms-Laubach (~A. moebii Solms-Laubach) from that island; the latter
has not been collected on Rodrigues.
PHAEOPHYCEAE
ECTOCARPALES
ECTOCARPACEAE
Feldmannia Hamel
*Feldmannia irregularis (Kützing) G. Hamel, 1939: XVII
References: Jaasund, 1969: 206, figure 6 (~Feldmannia irregularis (Kützing) G.
Hamel); Clayton, 1974: 777, figures 19, 20 (~Giffordia irregularis (Kützing)
Joly); Jaasund, 1976: 35, figure 71 (~G. conifera (Børgesen) Taylor); Tseng,
1984: 168, pl. 85, figure 4 (~Feldmannia irregularis); Womersley, 1987: 42,
figures 6D, 8A–C; Littler and Littler, 2000: 242, figure p. 243.
Type locality. Adriatic Sea.
Vouchers. HEC 14645 (zF), 19 September 2001, Gravier (s.s. 16); HEC
14750 (zF), 22 September 2001, Grand Baie (s.s. 11); HEC 14838 (zF), 27
September 2001, Baie de l’Hermitage (s.s. 17).
Ecology. On sand-covered rock under the overhanging limestone cliff wall at
high tide level, as well as in the low intertidal, epilithic and epiphytic on
Codium.
Distribution. Australia, Bangladesh, India, Kuwait, Maldives, Mauritius (Børgesen,
1941: 22–31, figures 8–11; 1948: 44), Mozambique, Pakistan, Rodrigues
(this paper), Saudi Arabia, Somalia, South Africa, Sri Lanka, Tanzania, Yemen.
Hincksia Gray
*Hincksia mitchelliae (Harvey) P. Silva, in Silva, Meñez and Moe, 1987: 73, 130
References: Børgesen, 1948: 44–45, figure 23 (~Ectocarpus mitchelliae Harvey);
Jaasund, 1976: 35, figure 35 (~Giffordia mitchelliae (Harvey) Hamel); Tseng,
1984: 170, pl. 86, figure 2 (~G. mitchellae); Lawson and John, 1987: 108, pl. 11,
figure 1 (~G. mitchelliae); Womersley, 1987: 52, figures 10D, 12E–G (~G.
mitchelliae); Dinh et al., 1993: 115, figure 78 (~G. mitchellae); Cribb, 1996: 47,
figure p. 46 (~G. mitchelliae); Littler and Littler, 2000: 242, figure p. 243; Payri
et al., 2000: 128, figure p. 127.
Type locality. Nantucket, Massachusetts, USA.
Vouchers. HEC 14709 (zF), 20 September 2001, Rivière Banane (s.s. 12);
HEC 14725 (zF) and HEC 14721 (zF), 21 September 2001, Petite Butte
(s.s. 24); HEC 14748 (zF): 22 September 2001, Grand Baie (s.s. 11).
Ecology. On shell debris and pebbles, on silty sand, or epiphytic on Turbinaria,
Sargassum and Codium, under mean low water mark.
Distribution. Australia, Bangladesh, India, Iran, Kenya, Kuwait, Mauritius (Børgesen,
1941: 7–16, figure 1–6; 1948: 44–45, figure 23), Pakistan, Réunion (Payri, 1985:
640), Rodrigues (this paper), Saudi Arabia, Seychelles, South Africa, Tanzania.

Marine green and brown algae of Rodrigues 2999
SPHACELARIALES
SPHACELARIACEAE
Sphacelaria Lyngbye
Sphacelaria tribuloides Meneghini, 1840: 2
References: Jaasund, 1976: 37, figure 76; Prud’homme van Reine, 1982: 179–188,
figures 422–454; Tseng, 1984: 204, pl. 103, figure 2; Womersley, 1987: 160–162,
figures 45G, 52A–C; Littler and Littler, 2000: 252, figure p. 253.
Type locality. La Spezia, Italy.
Vouchers. HEC 14649 (zF), 19 September 2001, Gravier (s.s. 16); HEC
14694 (zF), 20 September 2001, Rivière Banane (s.s. 12); HEC 14835 (zF), 27
September 2001, Baie de l’Hermitage (s.s. 17).
Ecology. Epilithic in mid-intertidal rock pools as well as epiphytic on Centroceras
clavulatum in the upper intertidal.
Distribution. Australia, Bahrain, Bangladesh, Chagos Archipelago, India,
Indonesia, Kenya, Kuwait, Maldives, Mauritius (Børgesen, 1941: 41–42,
figure 18), Oman, Rodrigues (Dickie, 1877a: 6~Sphacelaria rigida Hering), Saudi
Arabia, Seychelles, Singapore, South Africa, Tanzania.
DICTYOTALES
DICTYOTACEAE
Dictyota Lamouroux
A recent monographic study of the genus Dictyota in the Indian Ocean
(De Clerck, 2003), based on a morphometric approach, resulted in a reduction of
the total number of Dictyota species for that region from 43 to 23, and included
the description of two new species. Due to taxonomic confusion and the
occurrence of numerous misapplied names (Coppejans et al., 2001: 404, 408–409)
distributional data based on literature reports should be treated with care.
Key to the species from Rodrigues
1 Thalli surface with surface proliferations (sometimes sparse); sporangia surrounded by
an involucrum of radially elongated cortical cells; thalli in situ non-iridescent; apical
parts sometimes recurved . . . . . . . . . . . . . . D. cervicornis
– Thalli lacking surface proliferations; sporangia not surrounded by an involucrum;
thalli in situ yellowish to blue iridescent; apical parts never recurved . . . . . 2
2 Interdichotomies markedly longer than wide (L/Bw2); apices acute; thalli not closely
adherent to the substrate; apices of the same colour as the rest of the thallus D. ceylanica
– Interdichotomies slighty longer than wide (L/B: 1–1.4); apices obtuse to rounded;
completely prostrate or forming hemispherical tufts; apices slightly darker than the
rest of the thallus . . . . . . . . . . . . . . . . . . . . 3
3 Thalli prostrate, closely adherent to the substrate, often forming exensive mats on
acroporoid corals . . . . . . . . . . . . . . . . . D. friabilis
– Thalli forming hemispherical tufts . . . . . . . . . . . D. bartayresiana
*Dictyota bartayresiana Lamouroux, 1809b: 43
References: Kützing, 1859: 8, pl. 16, figure 1; Taylor, 1960: 219, pl. 30, figure 2 (~D.
bartayresii Lamouroux); Tsuda, 1972: 95, pl. 3, figures 2, 3 (~D. bartayresii); Hörnig
et al., 1992: 56, figure 5 (as D. neglecta Hörnig and Schnetter); Cribb, 1996: 43,
figure p. 42; Littler and Littler, 2000: 260, figure p. 261; Payri et al., 2000: 132,
figure p. 133; De Clerck, 2003: 37–41, figures 9, 10.

3000 E. Coppejans et al.
Type locality. [Antilles], Caribbean Sea.
Voucher. HEC 14765 (zF), 25 September 2001, Passe Grand Bassin (s.s. 2).
Ecology. Epilithic in turbid water of the lagoon, shallow subtidal.
Distribution. Indonesia, Kenya, Madagascar, Mauritius (Jagtap, 1993: table I~Dictyota
bartayresii Lamouroux), Pakistan, Rodrigues (this paper), Sri Lanka,
Tanzania.
*Dictyota cervicornis Kützing, 1859: 11, pl. 24, figure 2
References: Okamura, 1913: 31–32, pl. 108, figures 1–8 (as D. divaricata
Lamouroux); Cribb, 1954: 22, pl. 3, figure 3 (~D. pardalis Kützing f.
pseudohamata Cribb); Taylor, 1960: 222: pl. 31, figure 2; Tsuda, 1972: 95–96,
pl. 3, figure 4, pl. 4, figure 1; Jaasund, 1976: 75–76, figures 1C, 2A, H, 3A, B
(under D. cervicornis and ~D. pardalis); Tseng, 1984: 192, pl. 97, figure 2;
Coppejans et al., 1995b: 180, figures 9, 10; Trono, 1997: 106, figure 73; Littler
and Littler, 2000: 260, figure p. 261; De Clerck et al., 2002: 415, figures 2–4;
De Clerck, 2003: 42–51, figures 11–14.
Type locality. Vera Cruz, Mexico.
Vouchers. HEC 14621, 18 September 2001, western side of Cotton Bay
(s.s. 13); HEC 14652, 19 September 2001, Gravier (s.s. 16); HEC 14766, 25 September
2001, Passe Grand Bassin (s.s. 2); HEC 14858, 30 September 2001, southwestern
part of the lagoon (s.s. 27).
Ecology. Epilithic in the intertidal, more rarely in the shallow subtidal zone.
Distribution. Australia, Eritrea, India, Indonesia, Iran, Kenya, Kuwait,
Madagascar, Malaysia, Mauritius (Jagtap, 1993: table I), Mozambique, Pakistan,
Réunion (Jadin, 1935: 160~Dictyota indica Sonder ex Kützing), Rodrigues (this
paper), Seychelles, Singapore, Somalia, South Africa, Sri Lanka, Tanzania, Thailand,
Yemen.
*Dictyota ceylanica Kützing, 1859: 11, pl. 25, figure 1
References: Cribb, 1954: 21, pl. 3, figure 9 (~D. divaricata); Jaasund, 1970: 76–77,
figures 2E, 3E, F, I (~D. divaricata Lamouroux and D. ceylanica); Tseng, 1984:
192, pl. 97, figure 4 (~D. divaricata); Coppejans et al., 1995b: figures 19, 21
(~D. divaricata and ~D. cf. dichotoma (Hudson) Lamouroux var. intricata (C.
Agardh) Greville); De Clerck and Coppejans, 1997: 413–414; De Clerck, 2003:
52–57, figures 15, 16; Littler and Littler, 2003: 168, top figure p. 169.
Type locality. Sri Lanka.
Voucher. HEC 14745 (zF), 22 September 2001, Grand Baie (s.s. 11).
Ecology. Epilithic in the shallow subtidal zone.
Distribution. Australia, India, Indonesia, Kenya, Mauritius (De Clerck, 2003: 52),
Pakistan, Rodrigues (this paper), Seychelles, Somalia, Sri Lanka, Tanzania, Yemen.
*Dictyota friabilis Setchell, 1926: 91–92, pl. 13, figures 4–7, pl. 20, figure 1
References: Dawson, 1954: 401, figure 16A, B; Womersley and Bailey, 1970:
290–291; Magruder and Hunt, 1979: 43, unnumbered pl.; Tseng, 1984: 194,
pl. 98, figure 1; Coppejans et al., 1995b: figure 16 (as D. sp. 4), Trono, 1997: 109,
figure 75; De Clerck and Coppejans, 1997: 417; Payri et al., 2000: 132,

Marine green and brown algae of Rodrigues 3001
figure p. 133; De Clerck, 2003: 89–93, figures 28, 29; Littler and Littler, 2003:
168, middle figure p. 169.
Type locality. Tafaa Point, Tahiti.
Vouchers. HEC 14808, 26 September 2001, Chaland (s.s. 8); HEC 14879, 1
October 2001, Totor (s.s. 9).
Ecology. Epilithic between branches of acroporid corals at 15 m depth.
Distribution. Aldabra Islands, Bangladesh, Diego Garcia Atoll, Egypt,
Kenya, Maldives, Malaysia, Mauritius (De Clerck, 2003: 89), Réunion (De
Clerck, 2003: 89), Rodrigues (this paper), Saudi Arabia, Seychelles, Sri Lanka,
Tanzania.
Unchecked data from literature
Dictyota dichotoma (Hudson) Lamouroux, 1809a: 42
Mentioned by Dickie (1877a) but not among our recent collection.
According to De Clerck (2003), this species does not occur in the tropical part
of the Indian Ocean. Specimens identified as such belong to a variety of
species, most commonly D. ciliolata Sonder ex Kützing and D. ceylanica Kützing.
Lobophora J. Agardh
Lobophora variegata (Lamouroux) Womersley ex de Oliveira, 1977: 217
References: Papenfuss, 1943: 463–468, figures 1–15 (as Pocockiella variegata
(Lamouroux) Papenfuss); Jaasund, 1976: 43, figure 88 (as P. variegata);
Tseng, 1984: 196, pl. 99, figure 2; Womersley, 1987: 127, figures 91F, G, 92A;
Lewmanomont and Ogawa, 1995: 74; Calumpong and Meñez, 1996: 128, 2
figures; Cribb, 1996: 49, figure p. 48; Littler and Littler, 2000: 268, figure p. 269;
Payri et al., 2000: 136, figure p. 137; Skelton and South, 2002: 158, figure 18C, D,
G; Littler and Littler, 2003: 172, bottom figure p. 173.
Type locality. Antilles, Caribbean Sea.
Vouchers. HEC 14671, 18 September 2001, western side of Cotton Bay
(s.s. 13); HEC 14695 and HEC 14697, 20 September 2001, Rivière Banane
(s.s. 12).
Ecology. Epilithic in intertidal rock pools.
Distribution. Aldabra Islands, Andaman Islands, Australia, Bahrain, Bangladesh,
Chagos Archipelago, Diego Garcia Atoll, India, Indonesia, Iran, Kenya,
Laccadives, Madagascar, Maldives, Mauritius (Børgesen, 1941: 47–48; 1948: 46),
Mozambique, Nicobar Islands, Oman, Pakistan, Réunion (Jadin, 1935:
161~Zonaria variegata (Lamouroux) C. Agardh), Rodrigues (Dickie, 1877a:
6~Zonaria nigrescens Sonder), Saudi Arabia, Saya de Malha Bank, Seychelles,
Somalia, South Africa, Sri Lanka, Tanzania.
Padina Adanson
Key to the species from Rodrigues
1 The middle parts of the thallus composed of two to three cell layers, increasing to four
layers near the base; hair bands present on both sides of the thallus . P. boergesenii
– The entire thallus composed of two cell layers; hair bands present on the outer surface
only (the surface away from the enrolled apex) . . . . . . . . . P. minor

3002 E. Coppejans et al.
*Padina boergesenii Allender and Kraft, 1983: 87, figures 6C, H, I, 7C, D
References: De Clerck and Coppejans, 1996: 230, figures 48, 50, 51; Littler and
Littler, 2000: 272, figure p. 273; Muylle, 2000: 84–92, pls 15–22, table 3; Littler
and Littler, 2003: 174, top figure p. 175.
Type locality. Virgin Islands, Caribbean Sea.
Vouchers. HEC 14653 (zF), 19 September 2001, Gravier (s.s. 16); HEC
14670, 18 September 2001, western side of Cotton Bay (s.s. 13); HEC 14681
(zF), 20 September 2001, Rivière Banane (s.s. 12); HEC 14722 (zF), 21
September 2001, Petite Butte (s.s. 24); HEC 14777, 25 September 2001, Passe
Grand Bassin (s.s. 2).
Ecology. Epilithic in the intertidal and the shallow parts of the sublittoral zone.
Distribution. Based on Muylle (2000: 91–92): Australia, India, Indonesia, Kenya,
Oman, Pakistan, Réunion (Muylle, 2000: 86), Rodrigues (this paper), Saudi Arabia,
South Africa, Tanzania, Yemen.
Note. The specimens of HEC 14681 present some sporangia on the upper
thallus surface.
*Padina minor Yamada, 1925: 251–252, figure V
References: Tseng, 1984: 200, pl. 101, figure 1; Lewmanomont and Ogawa, 1995: 77;
Calumpong and Meñez, 1996: 126, 2 figures; De Clerck and Coppejans, 1996:
230–231, figures 49, 52; Trono, 1997: 115, figure 79; Muylle, 2000: 181–186,
pls 33–39, table 4.
Type locality. Garan-bi (Cape O-luan), Taiwan.
Vouchers. HEC 14670b, 18 September 2001, western side of Cotton Bay (s.s. 13);
HEC 14680 (zF), 20 September 2001, Rivière Banane (s.s. 12), HEC 14776, 24
September 2001, Grand Baie (s.s. 11); HEC 14791, 25 September 2001, Passe Grand
Bassin (s.s. 4).
Ecology. Epilithic in intertidal rock pools, sometimes mixed with P. boergesenii.
Distribution. Based on Muylle (2000: 185–186): Indonesia, Japan, Kenya,
Mauritius, Oman, Philippines, Rodrigues (this paper), Saudi Arabia, Seychelles,
Sri Lanka, Taiwan, Tanzania, Thailand, Yemen.
Note. Morphologically, P. minor is very similar to P. boryana Thivy. Nevertheless,
the frond of the former is composed of no more than two cell layers,
whereas the latter is two to three cell layers thick.
General remarks on the distribution of Padina in the Mascarene Islands
Børgesen (1941: 49) mentions two Padina species from Mauritius:
P. gymnospora (Kützing) Sonder and P. boryana Thivy. The latter is very similar to
P. minor. Neither species mentioned by Børgesen was collected on Rodrigues.
Unchecked data from literature
Padina pavonica (Linnaeus) Thivy, in Taylor, 1960: 234–235
Mentioned by Dickie (1877a) but not among our recent collection.
It is improbable that this species occurs in the tropical part of the Indian Ocean
(Muylle, 2000).

Table 3.
Comparison of morphological and anatomical characters of the different species of Cladosiphon with the material from Rodrigues.
C. filum C. vermicularis C. mauritianus C. occidentalis Specimen from Rodrigues
Thallus height 10–50 cm 10–50 cm 30 cm 15–20 cm 5–25 cm
Diameter of the axes 2–4 mm 1.4–5 mm 2 mm 0.75–2.5 mm 1.25 mm
Medulla
Filaments 25–50 mm
diameter
Filaments 25–45 mm
diameter
Not mentioned Filaments 50–112 mm
diameter;
Filaments 20–50 mm
diameter; cells 50 mm long
cells 200–400 mm long
160 mm thick;
cells 19–28 mm long
Cortex
400–500 mm thick;
20–30 cells
200–400 mm thick;
15–30 cells
200 mm thick;
13–15 cells
225 mm long; 8–18 cells;
cell diameter
6–8.4 mm
Hairs 20–25 mm diameter 10–12 mm diameter Not mentioned Not mentioned Present but difficult to
Sporangia Unilocularzplurilocular Unilocular (subcortical)
zplurilocular
Unilocular (rare)
zplurilocular
(terminal)
Plurilocular (30–38 mm
diameter, 56–80 mm long)
observe
Plurilocular (45–60 mm
long);
unilocular not observed
Distribution Australia Australia Mauritius Kuwait, Tanzania Rodrigues
Sources Womersley (1987: 120–122,
Børgesen (1941: Taylor (1960)
Personal observations
figures 35B, 36F, G, 37A)
54–57, figure 22)
Womersley (1987:
122–124,
figures 35C, 37B–E)
Marine green and brown algae of Rodrigues 3003

3004 E. Coppejans et al.
CHORDARIALES
CHORDARIACEAE
Cladosiphon Kützing
Four species of Cladosiphon occur in the Indian Ocean: C. filum (Harvey) Kylin,
C. mauritianus Børgesen, C. occidentalis Kylin and C. vermicularis (J. Agardh)
Kylin (Silva et al., 1996: 616–617). A synthesis of their morphological and
anatomical characters is given in table 3.
After comparison of the above-mentioned characters it appears that the
material from Rodrigues belongs to Cladosiphon mauritianus. Nevertheless, it
should be emphasized that C. occidentalis and C. mauritianus are very similar.
Further research should clarify if they are two different species or if they have to be
synonymized.
*Cladosiphon mauritianus Børgesen, 1941: 54–57, figure 22, pl. II
(figures 25, 26)
Reference: Børgesen, 1941: 54–57, figure 22, pl. II (~C. mauritianum).
Type locality. Cannoniers Point, Mauritius.
Vouchers. HEC 14789 (zF), 25 September 2001, Passe Grand Bassin (s.s. 4).
Ecology. Epilithic close to spring low water mark, in a pool. Only a single,
large specimen observed.
Distribution. Mauritius (Børgesen, 1941: 54–57, figure 22, pl. II), Rodrigues
(this paper).
Unchecked data from literature
Eudesme J. Agardh
Eudesme virescens (Carmichael ex Berkeley) J. Agardh, 1882: 31
Mentioned by Dickie (1877a, as Mesogloia virescens Carmichael ex Berkeley)
but not among our recent collection.
This species has been described from different localities around Great Britain.
The single observation of this species in the Indian Ocean is that of Dickie (1877a)
on Rodrigues. It might represent a misidentification of Cladosiphon mauritianus,
which is superficially very similar.
SCYTOSIPHONALES
CHNOOSPORACEAE
Chnoospora J. Agardh
Chnoospora implexa J. Agardh, 1848: 172
(figures 27, 28)
References: Jaasund, 1976: 49, figure 99; Tseng, 1984: 184, pl. 93, figure 1; Cribb,
1996: 39, figure p. 38; Payri et al., 2000: 142, figure p. 143.
Type locality. Near Tor, Sinai Peninsula, Egypt.
Vouchers. HEC 14611 and HEC 14613, 18 September 2001, western side of
Cotton Bay (s.s. 13); HEC 14674 (zF), 20 September 2001, Rivière Banane
(s.s. 12); HEC 14719, 20 September 2001, Totor (s.s. 9).

Marine green and brown algae of Rodrigues 3005
FIGS 25–30. Phaeophyta. (25, 26) Cladosiphon mauritianus (HEC 14789b): (25) general
morphology; (26) apical branches. (27, 28) Chnoospora implexa (HEC 14674b): (27)
compact form; (28) thin, slender form. (29) Hydroclathrus tenuis (HEC 14756d). (30)
Asteronema breviarticulatum, rope-like appearance of intertwined filaments (HEC
14884). Scale bars: 2 cm (25); 1 cm (26–30).
Ecology. Abundant in intertidal pools, but also observed at about spring low
water mark.
Distribution. Bangladesh, India, Indonesia, Kenya, Mauritius (Børgesen,
1941: 63–65; 1948: 50; 1953: 18), Réunion (Jadin, 1935: 158), Rodrigues (Dickie,
1877a: 6), Seychelles, Tanzania.
Note. At some sites (Cotton Bay and Rivière Banane), different growth
stages are present: young, hemispherical, densely intricated, rubbery-stiff tufts of
10 cm diameter, branches with short interdichotomies (2–4 mm, figure 27),

3006 E. Coppejans et al.
through intermediates, to old, laxly branched, suppler plants, up to 25 cm long,
branches with interdichotomies up to 3 cm long (figure 28).
SCYTOSIPHONACEAE
Colpomenia (Endlicher) Derbès and Solier
Colpomenia sinuosa (Mertens ex Roth) Derbès and Solier, in Castagne, 1851: 95
References: Clayton, 1975: 187, figures 5–7, 12, 13; Jaasund, 1976: 47, figure 95;
Parsons, 1982: 291, figures 2, 3, 11, 12; Tseng, 1984: 184, pl. 93, figure 4;
Womersley, 1987: 297, figures 107A, 108E, F; Nguyen and Lu, 1993: 126,
figure 84; Lewmanomont and Ogawa, 1995: 67; Cribb, 1996: 39, figure p. 38;
Littler and Littler, 2000: 248, figure p. 249; Payri et al., 2000: 144, figure p. 145;
Skelton and South, 2002: 158, figure 18E, F.
Type locality. Near Cádiz, Spain.
Vouchers. HEC 14613, 18 September 2001, western side of Cotton Bay
(s.s. 13); HEC 14789, 25 September 2001, Passe Grand Bassin (s.s. 4).
Ecology. Very abundant in middle and low intertidal; epilithic.
Distribution. Andaman Islands, Australia, Bahrain, Bangladesh, India,
Indonesia, Iran, Kenya, Kuwait, Laccadives, Madagascar, Malaysia, Mauritius
(Børgesen, 1941: 61–62, 1948: 49), Mozambique, Pakistan, Réunion (Jadin, 1935:
159~Hydroclathrus sinuosus (Mertens ex Roth) Zanardini), Rodrigues (Dickie,
1877a: 6, as Asperococcus sinuosus (C. Agardh) Zanardini), Saudi Arabia,
Seychelles, Singapore, Somalia, South Africa, Sri Lanka, Tanzania, Yemen.
Hydroclathrus Bory de Saint-Vincent
Key to the species from Rodrigues
1 Thallus rather stiff, forming a three-dimensional, perforated, hollow structure, the
tissue straps 600–900 mm thick (according to Tseng, 1984: 186) . . . H. clathratus
– Thallus very supple, forming very long reticulate straps with narrow tissue bridges
around the perforations; tissue straps 250–300 mm thick (according to Tseng, 1984:
186). . . . . . . . . . . . . . . . . . . . . . H. tenuis
Hydroclathrus clathratus (C. Agardh) Howe, 1920: 590
References: Taylor, 1960: 261, pl. 36, figure 5; Jaasund, 1976: 47, figure 96; Tseng,
1984: 186, pl. 94, figure 2; Womersley, 1987: 300, figures 109A, 110A, B;
Coppejans et al., 1995b: 178, figure 1; Cribb, 1996: 49, figure p. 48; Lewmanomont
and Ogawa, 1995: 73; Littler and Littler, 2000: 248, figure p. 249; Payri
et al., 2000: 144, figure p. 145; Skelton and South, 2002: 158, figure 19A; Littler
and Littler, 2003: 178, top figure p. 179.
Type locality. Uncertain.
Vouchers. HEC 14675azb (zF), 20 September 2001, Rivière Banane
(s.s. 12); HEC 14756a, 22 September 2001, Grand Baie (s.s. 11); HEC 14786, 25
September 2001, Passe Grand Bassin (s.s. 1).
Ecology. Epilithic, from high intertidal (rare) down to spring low water mark
(more frequent).

Marine green and brown algae of Rodrigues 3007
Distribution. Aldabra Islands, Andaman Islands, Australia, Bahrain, Bangladesh,
Diego Garcia Atoll, India, Indonesia, Kenya, Kuwait, Laccadives, Malaysia,
Maldives, Mauritius (Børgesen, 1941: 62, 1948: 49–50), Mozambique, Nicobar
Islands, Pakistan, Réunion (Montagne and Millardet, 1862: 21~Hydroclathrus
cancellatus Bory de Saint-Vincent), Rodrigues (Dickie, 1877a: 6), Saudi Arabia,
Seychelles, Singapore, Somalia, South Africa, Sri Lanka, Tanzania.
Note. The crisp, three-dimensional thalli of H. clathratus mainly grow epilithic
at about low water mark. The suppler, strap-like thalli of H. tenuis were
usually entangled with other seaweeds (e.g. Sargassum) or corals, although it has
also been found drifting in the lagoon. In a few instances, we observed that
H. clathratus, exposed at low tide to the air, was closely associated with thalli of
H. tenuis, continuously submerged in the rock pool next to it. This casts doubt
on the taxonomic identity of H. tenuis. Womersley (1987: 302) states that
‘H. clathratus is distinctive in form but varies considerably in compactness of
the net, the more compact forms usually occurring in shallow water with more
wave action’. He does not refer to H. tenuis.
*Hydroclathrus tenuis Tseng and Lu, 1983: 185, figure 1; pl. 1, figure 1a
(figure 29)
References: Tseng, 1984: 186, pl. 94, figure 3; Verheij and Prud’homme van Reine,
1993: 435, pl. 13, figure 1; Trono, 1997: 123, figure 83; Coppejans et al., 2000: 60,
figure 22.
Type locality. Xisha Island, Guangdong Province, China.
Voucher. HEC 14756d, 22 September 2001, Grand Baie (s.s. 11).
Ecology. Intertidal, about spring low tide level, wrapped around coral
boulders. Also found drifting in the lagoon in huge quantities, locally forming a
floating mass of 0.5 m thick.
Distribution. China, Indonesia, Rodrigues (this paper), Tanzania.
Notes. (1) See note for H. clathratus. (2) According to Tseng (1984: 186) this
species is endemic to China. Since then it has been reported from one site in
Indonesia (Verheij and Prud’homme van Reine, 1993: 435), from the Philippines
(Trono, 1997: 123) and from several locations in Tanzania (Coppejans et al.,
2000: 60). (3) When decaying, H. tenuis turns green. As a result it has been
identified as Ulva reticulata in previous ecological studies of Rodrigues, based on
the morphological resemblance.
FUCALES
SARGASSACEAE
Sargassum C. Agardh
Key to the species from Rodrigues
1 Leaves with a double series of teeth at the apical part (duplicated margin); all axes
smooth . . . . . . . . . . . . . . . . . . . S. cristaefolium
– Leaves without duplicated margin at the apex; axes and aerocysts muricate S. polycystum
*Sargassum cristaefolium C. Agardh, 1820: 13
References: Jaasund, 1976: 57, figure 113 (~S. duplicatum J. Agardh); Womersley

3008 E. Coppejans et al.
and Bailey, 1970: 296, pl. 25, figures 7, 15; Tseng, 1984: 228, pl. 115, figure 1
(~S. duplicatum); Moorjani and Simpson, 1988: 20, pl. 38b (~S. duplicatum);
Verheij and Prud’homme van Reine, 1993: 432, pl. 12:2; Coppejans et al., 1995b:
190, figure 31; Calumpong and Meñez, 1996: 134, unnumbered figure; Trono,
1997: 133, figure 89A; Skelton and South, 2002: 159, figure 20; Littler and
Littler, 2003: 180, bottom figure p. 181.
Type locality. Unknown.
Voucher. HEC 14616, 18 September 2001, western part of Cotton Bay
(s.s. 13).
Ecology. Frequent, epilithic in rather deep intertidal pools.
Distribution. Andaman Islands, Australia, Comores, India, Indonesia, Kenya,
Laccadives, Madagascar, Malaysia, Mauritius (Børgesen, 1941: 68), Nicobar
Islands, Oman, Réunion (Montagne and Millardet, 1862: 22), Rodrigues (this
paper), Seychelles, Singapore, Somalia, Sri Lanka, Tanzania, Yemen.
*Sargassum polycystum C. Agardh, 1824: 304
References: Jaasund, 1976: 57, figure 115; Tseng, 1984: 236, pl. 119, figure 1;
Lewmanomont and Ogawa, 1995: 84; Cribb, 1996: 59, figure p. 58; Skelton
and South, 2002: 160, figure 21; Littler and Littler, 2003: 184, top
figure p. 185.
Type locality. Sunda Strait, Indonesia.
Voucher. HEC 14720, 21 September 2001, Petite Butte (s.s. 24).
Ecology. Epilithic at about spring low water level.
Distribution. Andaman Islands, Burma, India, Indonesia, Madagascar,
Malaysia, Mauritius (Børgesen, 1941: 68), Pakistan, Réunion (Jadin, 1935: 160),
Rodrigues (this paper), Seychelles, Singapore, Sri Lanka, Tanzania.
Sargassum sp.
Vouchers. HEC 14657a, 19 September 2001, Gravier (s.s. 16); HEC 14721
(zF), 21 September 2001, Petite Butte (s.s. 24).
Ecology. Epilithic in mid-intertidal rock pool and in shallow sublittoral.
General remarks on the distribution of Sargassum in the Mascarene Islands
Børgesen (1941: 66–73) mentions 13 Sargassum species from Mauritius amongst
which are both species identified from Rodrigues.
Unchecked data from literature
Sargassum ilicifolium (Turner) C. Agardh, 1820: 11
Mentioned by Dickie (1877a) but not among our recent collection.
Sargassum vulgare C. Agardh, 1820: 3–4, nom. illeg.
Mentioned by Dickie (1877a) but not among our recent collection.

Marine green and brown algae of Rodrigues 3009
Turbinaria Lamouroux
Turbinaria ornata (Turner) J. Agardh, 1848: 266
References: Taylor, 1964: 483–485, pl. 3, figures 1–6; Jaasund, 1976: 53, figure 105;
Tseng, 1984: 242, pl. 122, figure 1; Lewmanomont and Ogawa, 1995: 87;
Calumpong and Meñez, 1996: 137, unnumbered figure; Cribb, 1996: 63,
figure p. 62; Trono, 1997: 155, figure 100; Payri et al., 2000: 148, figure p. 149;
Skelton and South, 2002: 160, figure 19E; Littler and Littler, 2003: 186, bottom
figure p. 187.
Type locality. Not specified.
Voucher. HEC 14637, 18 September 2001, western side of Cotton Bay (s.s. 13).
Ecology. Epilithic in mid- to low intertidal rock pools.
Distribution. Aldabra Islands, Andaman Islands, Australia, Burma, Chagos
Archipelago, Christmas Islands, Comores, Diego Garcia Atoll, India, Indonesia,
Kenya, Laccadives, Madagascar, Malaysia, Maldives, Mauritius (Børgesen, 1941:
65–66), Mozambique, Nicobar Islands, Réunion (Jadin, 1935: 159), Rodrigues
(Dickie, 1877a: 6), Seychelles, Singapore, Somalia, South Africa, Sri Lanka, Tanzania,
Thailand.
Incertae sedis
Asteronema Delépine and Asensi
Asteronema breviarticulatum (J. Agardh) Ouriques and Bouzon, 2000: 271
(figure 30)
References: Tseng, 1984: 168, pl. 85, figure 1 (~Ectocarpus breviarticulatus J.
Agardh); De Clerck et al., 2002: 418, figures 13–15; Littler and Littler, 2003: 164,
top figure p. 165.
Type locality. San Agustin, Oaxaca, Mexico.
Voucher. HEC 14884 (zF), 3 October 2001, eastern part of Cotton Bay (s.s. 15).
Ecology. Forming extensive populations in a well-illuminated limestone rock
pool at high tide level, under the Bostrychia zone.
Distribution. Bangladesh, Burma, Christmas Island, India, Laccadives, Maldives,
Mauritius (Børgesen, 1941: 39–41, figure 17; 1948: 45), Réunion (Jadin,
1935: 158~Ectocarpus spongiosus Dickie), Rodrigues (this paper), Seychelles, Sri
Lanka.
Note. Recent molecular studies by Draisma et al. (2001) and Rousseau et al.
(2001) reveal that Asteronema is polyphyletic and not related to the Ectocarpales
Sensu lato. Unfortunately, Asteronema breviarticulatum itself was not included in
the analysis. Pending further studies, A. breviarticulatum is listed as Incertae
sedis rather than under Ectocarpales.
Discussion
Of the 26 seaweed taxa belonging to the Chlorophyceae (15 spp.) and
Phaeophyceae (11 spp.) mentioned from Rodrigues in Silva et al. (1996), mainly
based on Dickie’s (1877a, b) species lists, only 13 were recollected during this
expedition (seven greens, six browns). This could partly be explained by the
seasonality of the seaweed flora, but it is most probably due to a different species
concept. For example, Dictyota dichotoma and Padina pavonica, mentioned for

3010 E. Coppejans et al.
Rodrigues by Dickie, have been proven not to occur in the tropical part of the
Indian Ocean (De Clerck, 2003 and Muylle, 2000, respectively). Dickie (1877b)
mentions Halimeda tuna; we identified H. discoidea. Based on nuclear ribosomal
DNA and ITS sequences (Kooistra, in press) it can be concluded that Indo-Pacific
H. tuna and Indo-Pacific H. discoidea are conspecific. As a result of changed species
concepts, comparison of our results with the limited historical data is hazardous.
Our species list indicates that the green and brown algal flora of Rodrigues is
rather poor (53 species of Chlorophyta and 18 species of Phaeophyta) when
compared to that of Mauritius (117 species of Chlorophyta and 66 species of
Phaeophyta). It should be stressed though, that the numerous phycological studies
of Børgesen on algae from that island were based on collections made over many
years and different seasons. The current expedition to Rodrigues allowed 12
field trips (with approximately 31 collecting sites) by phycologists and some
supplementary collections by other expedition partners over a 2-week period. Up to
the last collecting trip new taxa were added to the species list, indicating that more
are likely to be discovered. Moreover, the outer reef flats and seaward reef slopes
have hardly been sampled by phycologists, obviously resulting in an underestimation
of the algal biodiversity of the island.
Another explanation of the limited algal flora of Rodrigues is the absence of
some habitats (see Schils et al., 2004). There is no natural mangrove vegetation.
Only one species, Rhizophora mucronata, has fairly recently been introduced in
some bays. They have still not been colonized by seaweed species typical for
mangroves. The sea-grass vegetation is very limited and occurs only in the low
intertidal and shallow subtidal zones. Moreover, it is solely composed of open
vegetation of the colonizing species Halophila ovalis and H. stipulacea, species with
leaves that grow and decay quickly. In these conditions, it is unlikely that epiphytic
cover or algal undergrowth can develop.
It should also be stressed that the species richness greatly differs from site to
site, with the richest sites being situated on the surf-exposed north-east coast
(Grand Baie, Rivière Banane, Cotton Bay), and markedly poorer sites being present
along the other, more sheltered and siltier coasts. Even so, the latter sites contain
species characteristic of sheltered habitats. The silty-sandy bottom of the vast
lagoon showed a patchy pattern: large areas were covered by dense mats of
filamentous cyanobacteria (not included in this study), whereas other large stretches
were covered by huge amounts of non-attached living algae such as Boodlea and
Hydroclathrus that moved around with the tidal currents. Local coral heads
markedly increase the biodiversity of the lagoon flora. Some species were collected
only in this habitat.
The absence of species that would be expected on an island under the given
climatological conditions is striking. For the Chlorophyta, the genus Chlorodesmis
is absent as a whole, Boergesenia forbesii was not collected, and the omnipresent
weedy species Ulva reticulata was not observed, not even in the eutrophicated
harbour of Port Mathurin. Other genera, such as Halimeda and Cladophora with
only two species each, are under-represented. Certain other genera, on the other
hand, are very well represented: of the genus Codium, seven species were recorded,
and of the genus Caulerpa, 17 taxa were found. For the Phaeophyceae the absence
of the genera Dictyopteris, Cystoseira (neither C. myrica (S. Gmelin) C. Agardh nor
C. trinodis (Forsskål) C. Agardh were observed) and Hormophysa is striking.

Marine green and brown algae of Rodrigues 3011
Finally, the discovery of an Udotea species possibly new to science is worth
mentioning.
For a more detailed biogeographical discussion of the seaweed flora of
Rodrigues, based on the results of this study, we refer to Schils et al. (2004).
Acknowledgements
The authors express their gratitude to the organizers of the Shoals of Capricorn
expedition to Rodrigues for the invitation and to the staff for their valuable help.
The expedition members M. Richmond and D. Paupiah are acknowledged for the
seaweed collecting during their dives. We wish to thank C. De Maire for mounting
and labelling the herbarium specimens. The anonymous referees are acknowledged
for their constructive remarks on the original manuscript. The participation of the
first author was partly financed by FWO (Fund for Scientific Research-Flanders)
grant No. G013601. O. De Clerck is a postdoctoral fellow of the FWO; T. Schils is
research assistant of the FWO. H. Verbruggen is indebted to the Bijzonder
Onderzoeksfonds of Ghent University for grant No. 011D9101.
The work described in this paper was undertaken as part of the Royal
Geographical Society (with IBG)–Royal Society Shoals of Capricorn Programme,
western Indian Ocean, 1998–2001. This is Shoals Contribution No. P031.
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Taxonomic index
Names in italics are mentioned as synonyms in this list.
Acetabularia: 2997
aegagropila (Valonia): 2975
agardhianum (Microdictyon): 2967
amadelpha (Avrainvillea): 2992
ambigua (Caulerpella): 2989
anastomosans (Phyllodictyon): 2974
annulata (Neomeris): 2996
arabicum (Codium): 2990
Asteronema: 3009
Avrainvillea: 2992
bartayresiana (Dictyota): 2999
bartayresii (Dictyota): 2999
bilimbata (Neomeris): 2996
boergesenii (Padina): 3002
Boodlea: 2970
Boodleopsis: 2993
boryana (Caulerpa, var.): 2989
brachygona (Chaetomorpha): 2968
brachypus (Caulerpa): 2979
breviarticulatum (Asteronema): 3009
Bryopsis: 2976
calyculus (Acetabularia): 2997
Caulerpa: 2978
Caulerpella: 2989
cavernosa (Dictyosphaeria): 2974
cervicornis (Dictyota): 3000
ceylanica (Dictyota): 3000
Chaetomorpha: 2968
Chamaedoris: 2971
Chlorophyta: 2963
Chnoospora: 3004
Cladophora: 2969
Cladophoropsis: 2971
Cladosiphon: 3004
clathrata (Enteromorpha): 2964
clathratus (Hydroclathrus): 3006
clavata (Acetabularia): 2997
Codium: 2990
coelothrix (Cladophora): 2969
Colpomenia: 3006
composita (Boodlea): 2970
compressa (Enteromorpha): 2965
conifera (Feldmannia): 2998
cristaefolium (Sargassum): 3007
cupressoides (Caulerpa): 2980
delphinii (Chamaedoris): 2971
dichotoma (Dictyota): 3001
Dictyosphaeria: 2973
Dictyota: 2999
discoidea (Halimeda): 2993
disticha (Caulerpa, forma): 2980
divaricata (Dictyota): 3000
duplicatum (Sargassum): 3007
duthieae (Codium): 2990
Ectocarpus (Asteronema, Hincksia):
3009, 2998
elegans (Caulerpa, forma): 2981
Enteromorpha: 2963
ericifolia (Caulerpa, var.): 2989
Eudesme: 3004
exposita (Caulerpa, forma): 2983
extricatum (Codium): 2991
farlowii (Caulerpa, forma): 2988
favulosa (Dictyosphaeria): 2974
Feldmannia: 2998
flexuosa (Enteromorpha): 2964
friabilis (Dictyota): 3000
Gayralia: 2965
Giffordia (Feldmannia): 2998
Halimeda: 2993
herpestica (Cladophoropsis): 2971
Hincksia: 2998
Hydroclathrus: 3006
ilicifolium (Sargassum): 3008
implexa (Chnoospora): 3004
indica (Bryopsis): 2976

3020 Marine green and brown algae of Rodrigues
indica (Dictyota): 3000
intestinalis (Enteromorpha): 2965
irregularis (Feldmannia): 2998
javensis (Rhipidosiphon): 2994
lactuca (Ulva): 2967
laetevirens (Caulerpa, var.): 2986
latissima (Ulva): 2967
lanuginosa (Caulerpa): 2981
lentillifera (Caulerpa): 2982
leprieurii (Bryopsis, var.): 2977
Lobophora: 3001
lucasii (Codium): 2991
lycopodium (Caulerpa, var.): 2980
mamillosa (Caulerpa, var.): 2989
mauritianus (Cladosiphon): 3004
mexicana (Caulerpa): 2983
Microdictyon: 2967
minor (Padina): 3002
mitchelliae (Hincksia): 2998
Monostroma: 2965
muscoides (Enteromorpha): 2965
neglecta (Dictyota): 2999
Neomeris: 2996
nummularia (Caulerpa): 2983
opuntia (Halimeda): 2993
ornata (Turbinaria): 3009
oxysperma (Gayralia): 2965
Padina: 3001
palmetta (Udotea): 2995
paradoxa (Enteromorpha, subsp.): 2964
pardalis (Dictyota): 3000
pavonica (Padina): 3002
peltata (Caulerpa): 2984
peltata (Caulerpa, var.): 2986
pennata (Bryopsis): 2976
pertusa (Ulva): 2966
Phaeophyta: 2998
Phyllodictyon: 2974
pocockiae (Codium): 2991
Pocockiella (Lobophora): 3001
polycystum (Sargassum): 3008
prostratum (Codium): 2991
pseudohamata (Dictyota, forma): 3000
pusilla (Boodleopsis): 2993
racemosa (Caulerpa): 2985
ramulosa (Enteromorpha): 2965
Rhipidosiphon: 2994
rigida (Ulva): 2966
Sargassum: 3007
secunda (Bryopsis, var.): 2977
serrulata (Caulerpa): 2986
sertularioides (Caulerpa): 2987
setchellii (Dictyosphaeria): 2974
sinuosa (Colpomenia): 3006
Sphacelaria: 2999
spongiosum (Codium): 2992
Struvea (Phyllodictyon): 2974
sundanensis (Cladophoropsis): 2971
taxifolia (Caulerpa): 2988
tenuis (Hydroclathrus): 3007
tenuius (Microdictyon): 2967
tomentosum (Codium): 2992
tribuloides (Sphacelaria): 2999
Turbinaria: 3009
tuna (Halimeda): 2994
Udotea: 2995
Ulva: 2966
vagabunda (Cladophora): 2969
Valonia: 2975
variegata (Lobophora): 3001
vaughanii (Codium): 2992
Ventricaria: 2975
ventricosa (Ventricaria): 2975
versluysii (Dictyosphaeria): 2974
virescens (Eudesme): 3004
vulgare (Sargassum): 3008
webbiana (Caulerpa): 2988