Balanophyllia spongiosa, Cairns, 2004

Cairns, S. D., 2004, The Azooxanthellate Scleractinia (Coelenterata: Anthozoa) of Australia, Records of the Australian Museum 56, pp. 259-329 : 313

Balanophyllia spongiosa n.sp.

Figs. 11 I,J, 12A–C

Records/Types. Holotype (type locality): 34°00'S 151°13'E (Inscription Point, Kurnell, NSW), 10.7 m, 20 January 1968, AM G13677, and septal fragment as SEM 1035, USNM 1008863 . Paratypes: from type locality, 7: 5, AM G13672 and 2, USNM 1008864 ; 33°59.6'S 151°13.8'E ( West Bare Island , La Perouse, Sydney) , depth unknown, April 1967, 1, AM G13678; 34°04'S 151°11'E (Cronulla) , 18 m, early 1967, 1, AM G13671 .

Description. Corallum ceratoid to subcylindrical, the holotype and largest corallum 14.1× 10.8 mm in CD and 23.4 mm in height, having a PD of 5.3 mm (ceratoid), but a majority of the paratypes are subcylindrical, having a pedicel diameter almost equal to that of the calice. Calice elliptical: GCD:LCD = 1.17–1.45. Corallum usually epithecate on lower half, this region often completely eroded or encrusted with other organisms. Above epitheca, costae are poorly defined and very porous, consisting of small, linearly arranged spines separated by very thin, shallow intercostal striae. Corallum white, but tissue of living coral appears to have been purple (pers. comm., C.J. Lawler) or black.

Septa hexamerally arranged in 5 incomplete cycles, the holotype having 82 septa (i.e., 17 pairs of S5). S1–2 equal in size, independent, only slightly exsert (about 1.6 mm), and relatively narrow, having a slightly concave axial edge. Entire axial edge of S1–2 finely and regularly dentate, each triangular tooth 65–70 µm in height, about 5 occurring every mm ( Figs. 11I,J). S3 about one-third size of the S1–2, also independent, and also having a dentate axial edge, the teeth being slightly coarser. Remaining septa (S4–5) arranged in a well-developed Pourtalès Plan, S5 adjacent to S1 and S2 always being much larger than those adjacent to S3, but the axial edges of each pair of S5 fusing before their adjacent S4 and this combined septum fusing again with the other S5 pair (or unflanked S4) within the half-system near the columella. Axial edges of S4–5 coarsely dentate to laciniate, and in the fusion region adjacent to the columella the axial protuberances are so well developed as to resemble columellar elements, giving the impression that the columella is extending outward and upward onto the septa ( Fig. 12C). Fossa quite shallow, containing an elongate, robust columella that may occupy up to 30% width of calice. Columella non-discrete (in that it merges with the axial edges of many of the septa), essentially flat-topped, and composed of up to 100 small (0.1 mm diameter), interconnected papillae.

Remarks. Among the Australian and Western Pacific species of Balanophyllia , B. spongiosa can be distinguished by its finely dentate axial edges of the S1–2; its large, flattopped columella; and the apparent extension of the columella onto the lower, axial edges of the S1–2, S5.

Etymology. spongia, Latin for “sponge” + osus, Latin suffix meaning “full of”, an allusion to the spongy nature of the columella and lower, axial edges of the larger septa

Distribution. Known only from the region of Sydney, New South Wales, 11– 18 m.