Azooxanthellate Scleractinia 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 
(Soda 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 (S1-3>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. S4 about 3/4 
width of the Sl-3; S5 quite small, only 1/5 width 
of the S4. 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, crescent¬ 
shaped 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 Milne Edwards 
and Haime, 1848a; T. carinatum Cairns, 1989; and 
T. incrustation 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. 
399 
Truncatoflabellum paripavoninum (Alcock, 1894) 
Flabellum pari-pavoninum Alcock, 1894: 187. 
Truncatoflabellum paripavoninum - Cairns, 1989: 72- 
73, pi. 37, figs, j—1, 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, 
la-c. 
Flabellum rubrum - Folkeson, 1919: 4-5 (in part: 
specimen #1). 
Truncatoflabellum spheniscus - Cairns, 1989: 65-66, 
pi. 32, figs, g-k; 1994: 76, pi. 33, figs. a-d.— 
Cairns and Zibrowius, 1997: 165-166 (in part: 
those specimens with large basal scars). 
New Records 
Soela: stn 01/69, 1, WAM 371-80. 
Lady: stn RW96-5, 2, NTM C8062. 
Remarks 
Although similar to T. angiostomum, particularly 
in septal shape and face angle, T. spheniscus can be 
distinguished from that species by its larger basal 
scar (10-12 mm in greater diameter), lesser edge 
angle (80°-90°), and smaller size with consequently 
fewer septa (see Table 4). 
Distribution 
Western Australia: continental shelf of 
northwestern coast (Joseph Bonaparte Gulf, Cape 
Jaubert and Long Island, Passage Islands); 16-32 
m. Elsewhere: western Pacific from Japan through 
Indonesia; Gulf of Carpenteria; Torres Strait; 2-174 
m (Cairns and Zibrowius 1997). 
Truncatoflabellum aculeatum (Milne Edwards 
and Haime, 1848a) 
Flabellum aculeatum Milne Edwards and Haime, 
1848a: 272, pi. 8, figs. 3, 3a. 
