Hydroids (Cnidaria, Hydrozoa) of the Danish expedition to

178
three alternate hydrothecae in two lateral rows
and a long apophysis below the distal-most hydrotheca.
Hydrocladia alternate, straight, with up to 10
segments, nodes transverse and distinct, flanked
by swellings of the segment ends, segments long
and thin, quite uniform in length (1.5–1.6 mm).
Hydrocladial hydrothecae in two lateral rows, in
strictly opposite pairs in the distal half of the
segment, members of a pair not contiguous on
any side, consecutive hydrothecae of one row
very far apart.
Hydrotheca curved, free part wedge-shaped
in lateral view, duck-billed in oblique view, adcauline
side adnate for less than half its length,
sharply bent where becoming free, adnate part
0.4 mm long, free adcauline side nearly horizontal,
straight to slightly concave, 0.55–0.60 mm
long, upper side of hydrotheca shaped like a
gabled roof, with lateral crease lines. Periderm of
distal part of hydrotheca very thin and flexible.
Opening very oblique, with one large, oval adcauline
opercular flap, sometimes repeatedly
present; perhaps also a small, very indistinct adcauline
opercular valve present. Hydranth with
about 20 tentacles, without abcauline caecum.
Gonothecae on stem, often opposite a hydrocladium.
Gonotheca oblong, about 2 mm long, maximal
diameter about 1 mm, distal end truncate,
opening on a short neck with wide diameter,
lateral wall of gonotheca with about 6 thick
annulations; near distal end an interior ring of
periderm knobs.
Remarks
With its relatively large, pinnate colonies, and
especially the widely spaced hydrothecal pairs
with their long wedge-shaped ends, Salacia sibogae
is quite easily identifiable in the present
fauna. All examined samples come from a small
area north-east of the Kei Island archipelago, not
far from the type locality of the species. Most
records lie in deeper waters, with a range of 40–
450 m (of the seven known records six are below
245 m, only one is from 40 m).
Although the identity of the present material
with Billard’s species is quite certain, the allocation
of this species to the genus Salacia is not
P. SCHUCHERT
entirely secure because there might be more than
just one opercular valve and the species appears
intermediate between the genera Dynamena and
Salacia. In many hydrothecae, the adcauline (upper)
margin is thinner and it looks like a short
adcauline opercular valve partitioned by a short
median tooth (Fig. 34D). This was only visible in
the stereomicroscope and the putative valve is
not distinctly demarcated at its base. It was not
possible to evaluate whether this is a true, rudimentary
operculum or only an illusion. However,
the hydrotheca is not entirely typical for the
genus Salacia and perhaps the genus Dynamena
might be more appropriate for this species. Millard
(1975) mentions that in Dynamena the upper
valve is usually smaller and it may have a median
partition (see Dynamena crisioides). However,
the distal part of the hydrotheca of S. sibogae is so
flimsy and difficult to observe that no clear answer
seems possible with ordinary light microscopy.
Distribution
Indonesia, Indian Ocean (Hirohito 1995). Type
locality: Kei Islands, 5.473°S, 132.000°E, 204 m,
on hard coralline sand.
Salacia punctagonangia (Hargitt, 1924)
Fig. 35.
Sertularia punctagonangia Hargitt, 1924: 469, pl. 6: fig. 23.
?Salacia spec. – Hirohito 1995: 185, fig. 60d–e.
Type material examined:
Sertularia punctagonangia, NMNH, slide reg. number
USNM 42655, part of a plume with male gonothecae.
Other material examined:
Kei Islands Expedition station 4, with female gonothecae.
Differential diagnosis
Similar to Salacia sibogae Billard, 1924 (see
above), but stem occasionally forked, 7 cm high,
nodes on stem absent in proximal region. Hydrocladial
hydrothecae smaller, subopposite, some
almost alternate, few opposite. Free adcauline
wall of hydrotheca convex in side view, crosssection
rounded and not roof-shaped, without
lateral crease lines. Gonotheca smooth-walled,
oblong oval, tapering below into pedicel, termi-