The Marine Fauna of New Zealand: Isopoda, Aegidae (Crustacea)

subOrdEr cymOthOIdA wägElE,
1989
Brandt and Poore (2003) provided a new classification
for the non-asellotan isopods (the ‘former Flabellifera’)
based on a thorough character analysis, and recognised
the subordinal separation of, among others, the Cymothoida
Wägele, 989 from the Sphaeromatidea Wägele,
989, as had earlier been proposed by Wägele ( 989).
That classification is followed here.
rEvAlIdAtION ANd dIAgNOsIs tO
bArybrOtIdAE hANsEN, 1890
barybrotidae Hansen, 890
Barybrotidae Hansen, 890: 66.– Monod, 934: 0.
diagnosis: Body evenly vaulted. Eyes dorso-lateral,
large. Antennae and antennule well developed; division
between peduncle and flagellum distinct; flagellae
multi-articulate. Antennule shorter than antenna.
Frontal lamina present, abutting clypeus; clypeus and
labrum present. Mouthparts forming buccal cone.
Mandible incisor broad, incisor tridentate; molar process
present, lamellar; lacinia mobilis and spine row
absent, represented by or 2 setae. Maxillule styliform,
with flattened terminal RS. Maxilla a simple minute
lobe, lacking RS. Maxilliped endite absent; palp with
4 articles, article 2 elongate, about 2.9 times proximal
width, articles 2–4 with hooked RS. Pereopods robust;
pereopods –3 with prehensile dactylus, about as
long or longer than propodus; superior distal angles
of ischium and merus strongly produced and setose.
Pereopods 4–7 ‘natatory’, with flattened basis, with superior
and inferior margins provided with continuous
row of long plumose setae. Pleon with 5 free pleonites
plus pleotelson. Pleopod rami lamellar, without ridges
or folding, with plumose marginal setae on both rami
of pleopods and 2, setation reduced or absent on
endopods of pleopods 3 and 4; pleopod 5 endopod
without setae.
Composition: The family has one monotypic genus
Barybrotes Schioedte & Meinert, 879a, the type species
of which is Barybrotes indus Schioedte & Meinert,
879a; other named species are junior synonyms of
the type species.
tAxONOmy
25
remarks: There are several character states that prevent
Barybrotes Schioedte & Meinert, 879a, being placed
in the Aegidae, and that require the reinstatement of
Hansen’s ( 890) family. Prime among these is that the
mouthparts, while reduced and probably used to feed
from fish prey, do not show homologous character
states with that of the Aegidae, nor the Corallanidae
and Tridentellidae. In particular the maxilla is a minute
single lobe lacking robust setae (similar to that seen in
the Corallanidae), not wide and flat with a distomesial
basal endite, and both maxilla lobes with hooked robust
setae as occurs in all Aegidae and also Cymothoidae;
the maxilliped is of a different form to that of the
Aegidae, notably with only four palp articles, with
article 2 elongate; and the mandible incisor retains
the cirolanid form, being wide and tridentate, though
somewhat narrower than seen in Cirolanidae. In the
past the genus has been referred to the nominate family
(e.g. Richardson 9 0; Thielemann 9 0; Monod 934)
or subfamily (Nierstrasz 93 ), to the Corallanidae
(Barnard 936) and more recently to the Aegidae (Pillai
954, 967; Brandt & Poore 2003; Kensley et al. 2007). I
have been unable to discover any published justification
for placing Barybrotes in the Aegidae.
There are numerous character states that strongly
suggest that Barybrotes has evolved from a Natatolanalike
cirolanid ancestor (Natatolana Bruce, 98 ; see
Keable 2006), including the proportions of the peduncular
articles of the antennule (articles and 2 short,
3 long) and antenna (articles 3 and 4 subequal in
length), presence of a prominent pappose robust seta
at the distal margin of antennular peduncle article 2,
flagellum of the antennule with short (‘ring-like’) articles
that may form a callynophore in males, elongate
frontal lamina, wide and tridentate mandible incisor
(though narrower than in the Cirolanidae), pereopods
–3 with the superior distal angles of the ischium and
merus produced and provided with long slender setae,
pereopods 5–7 with a flattened basis provided with
long plumose setae on superior and anterior margins
and along the mid-lateral margin. All these character
states are typical of Natatolana.
The diagnosis is based on an examined series of
specimens from the Zoological Museum, Natural History
Museum of Denmark, listed in Appendix 3.
distribution: Indian Ocean from East Africa (present
material) to Thailand; in the Pacific from Vietnam,
Indonesia and Philippines.