Azooxanthellate Scleractinia (Cnidaria: Anthozoa) - Western ...

AzooxantheIlate ScIeractinia of Western Australia
pairs of thin thecal edge spines present,
occasionally a different number on opposite edges
of the same corallum. Theca only lightly encrusted
with calcareous epifauna; however, one corallum
(Soela stn 05/82/42) is heavily infested with
acrothoracican cirripede borings. Theca light
brown, more intensely pigmented along the Sl-2
as radiating stripes. Septa hexamerally arranged in
5 cycles (Sl-3>S4>S5, 96 septa), the fifth cycle
complete at a GCD as small as 12 mm. Sl-3 slightly
exsert, having sinuous axial edges; in some
specimens S3 are narrower than Sl-2. 54 about 3/4
width of the Sl-3; S5 quite small, only 1/5 width
of the 54. Fossa deep and narrow, containing a
trabecular columella about 1.3 mm wide.
Anthocaulus: Only two specimens of the
attached anthocaulus stage are known (WAM
259-93, WAM 442-96, Fig 8b), both of which are
still firmly attached to a short anthocyathus stage
at a height of 8.8-8.9 mm. A fine, white, crescentshaped
line on the theca indicates the eventual
line of transverse division, which is also
indicated inside the corallum by an incipient
endothecal dissepiment. Pedicel of anthocauli
1.5-1.6 mm in diameter; a pair of elongate, (up
to 5 mm) hollow thecal edge spines also occurs
on the anthocaulus.
Remarks
Among the approximately 28 extant species
within the genus, only three others have
predominantly hexameral septal symmetry
arranged in 5 cycles: T. candeanum Mime Edwards
and Haime, 1848a; T. carinatum Cairns, 1989; and
T. incrustatum Cairns, 1989 (see Cairns 1989: Table
6). T. australiensis is most similar to T. candeanum,
particularly in shape, size, pigmentation, and
spination, but differs in having a larger scar
diameter, a non-scalloped calicular edge, and a
lower face angle, which results in a larger
GCD:LCD (1.95-2.35 vs 1.6-1.7 for T. candeanum).
Furthermore, although T. candeanum can have 5 full
cycles of septa, this number is usually not attained
until a GCD of about 24 mm, whereas 96 septa are
present in T. australiensis at the relatively small
GCD of 12 mm. T. australiensis is relatively easily
distinguished from other Western Australian
Truncatoflabellum by having 2 or 3 pairs of thecal
edge spines, brown-striped theca, and only 96
septa (Table 4).
Distribution
Western Australia: continental shelf of western
coast south of Cartier Island to Houtman Abrolhos
Islands; 90-180 m.
Etymology
This species is named for the continent from
which it was described.
Tnmcatoflabellum paripavoninum (Alcock, 1894)
Flabellum pari-pavonil1l1m Alcock, 1894: 187.
399
Trlll1catoflabellum paripavol1il1l1m Cairns, 1989: 72­
73, pI. 37, figs. j-I, pI. 38, fig. a (synonymy and
description); 1995: 113-114, pI. 37, figs. d-e.­
Cairns and Zibrowius, 1997: 169, fig. 22 f.
New Records
Soela: stn 01/84/60,1, WAM 577-84; stn 01/84/
77, 2: 1 (WAM 529-84), 1 (USNM 96650); stn 01/
84/120,2, WAM 699- and 702-84.
Distribution
Western Australia: continental slope of
northwestern coast from north of Browse Island to
south of Rowley Shoals; 394-530 m; soft substrates.
Elsewhere: Indo-West Pacific from Laccadive Sea
through Indonesia and Philippines and Kermadec
Islands; 411-1450 m (Cairns and Zibrowius 1997).
Truncatoflabellum spheniscus (Dana, 1846)
Euphyllia spheniscus Dana, 1846: 160-161, pI. 6, figs.
1a-