Dunocyathus wallaceae, Cairns, 2004

Cairns, S. D., 2004, The Azooxanthellate Scleractinia (Coelenterata: Anthozoa) of Australia, Records of the Australian Museum 56, pp. 259-329 : 292-293

Dunocyathus wallaceae n.sp.

Figs. 6F–J

Records/Types. Holotype: Franklin 03/99/D11, AM G16744 . Paratypes: Franklin 03/99/D8, 2 (including SEM 1001 ), USNM 1008835 ; Franklin 03/99/D10, 2, USNM 1008836 ; Franklin 03/99/D11, 21: 17, USNM 1008837 , 2 , WAM Z20516 , and 2, ZMUZ; Franklin 03/99/D12, 2, USNM 1008838 ; Franklin 03/99/D14, 1, USNM 1008839 . Type Locality: 20°14.490'S 151°47.530'E ( Marion Plateau , Queensland), 342 m.

Description. Corallum (anthocyathus) solitary, ceratoid to trochoid in shape (edge angle 30–35°), with a blunt, rounded, unattached base. Largest specimen (holotype) 4.4× 4.1 mm in CD and 4.8 mm in height. Calice slightly elliptical, the GCD:LCD ranging from 1.07 to 1.14. Costae straight and continuous from calice to a point approximately 0.6–0.8 mm above the base, which corresponds to a corallum diameter of about 1.9–2.0 mm. This basal region is sometimes delimited by a faint circumferential line, below which the corallum bears 20–30 small (0.15–0.20 mm tall), triangular spines ( Fig. 6H), and is assumed to be the region of the anthocyathus that is immersed in the basal anthocaulus just before dehiscence, although an anthocaulus has not been definitely identified in the material at hand. Costae near calice rectangular in cross section, as in D. parasiticus , with flat granular tops about 0.20 mm in width and vertical edges, but toward the base the costae become more triangular in cross section. Two mammiform granules occur across the width of a costa near the calice; granules 0.06–0.08 mm in diameter. Upper edges of costae exsert, projecting approximately 0.30 mm above the calicular edge, and alternate in position with the septa, as is characteristic for the genus. Intercostal grooves are wide (up to 0.25 mm near the calice) and flat ( Fig. 6J). Corallum white.

Septa hexamerally arranged in 3 cycles (24 septa) according to the formula: S1>S2>>S3, the full third cycle present in a corallum as small as GCD 2.7 mm. S1 up to 0.5 mm exsert and have very sinuous axial edges, which in turn are bordered by very slender (0.15–0.20 mm) paliform lobes. S2 only slightly less exsert and wide as the S1, also having very sinuous axial edges, but bordered by much larger and taller paliform lobes, the width up to 0.50 mm, or about the same width as the septa they border. S3 less exsert, rising just above the level of the exsert costae, and are very narrow, having a finer axial edge sinuosity and a laciniate axial margin. Fossa relatively shallow, the upper edges of the P2 rising to the level of the calicular edge. The 6 P2 form a crown encircling a small papillose columella composed of 1–4 interconnected elements.

Remarks. Only one other species is known in this genus, Dunocyathus parasiticus Tenison-Woods, 1878 , also known only from eastern Australia. They are similar in costal morphology, and septal and palar configuration and the fact that they have alternating costae and septa, but differ primarily regarding corallum shape, the anthocyathus of D. wallaceae being conical, that of D. parasiticus tympanoid (discoidal). Dunocyathus wallaceae also differs in having a tuberculate base, a coarser costal granulation, a slightly elliptical calice (that of D. parasiticus is circular), and less well-developed S3.

Etymology. Named in honour of Carden Wallace (MTQ), for her contributions to scleractinian taxonomy.

Distribution. Known only from the Marion Plateau, Queensland, 320– 414 m.