Ceramaster australis H.E.S. Clark, 2001

Mah, Christopher L., 2011, Taxonomy of high-latitude Goniasteridae (Subantarctic & Antarctic): one new genus, and three new species with an overview and key to taxa, Zootaxa 2759, pp. 1-48 : 6-7

Ceramaster australis H.E.S. Clark, 2001 in Clark & McKnight, 2001

( Figure 1 A–E)

H.E.S. Clark in H.E.S. Clark and McKnight, 2001: 36 (as Ceramaster patagonicus australis )

Distribution. Macquarie Ridge and New Caledonia, 148– 590 m.

Comments. Although placed as a subspecies of C. patagonicus , a number of characters, including the swollen marginals, the differing number of furrow spines, the absence of pedicellariae from the marginal plates, and the subambulacral spine arrangement and number support separation of this taxon from C. patagonicus .

Based only on the description, Ceramaster cognatus McKnight, 2006 may be a synonym of C. australis H.E.S. Clark, 2001 . Shared characters include the swollen marginals, the flattened abactinals with angular granules, and similar furrow spine morphology. Ceramaster australis has 18–19 marginal plates per interradius at R= 42 mm with four to six adambulacral furrow spines whereas C. cognatus has 20–21 marginals per interradius at R= 46 mm with five to six adambulacral furrow spines. Ceramaster cognatus differs only in the presence of scattered granules on the bare surfaces of the superomarginal plates that may indicate size or regional variation.

Material examined. USNM 1121579- PARATYPE. Macquarie Ridge 51°00 S, 162° 01’E, 333– 371 m. Coll. R/V Eltanin 8 Feb. 1965. (1 dry spec. R=4.2, r-2.9). MNHN (Paris) EcAh 12352 New Caledonia 18°49.40, 163°18.80, 585– 590 m. Coll. MUSORSTOM 4, Sept. 20, 1985.

Description. Body pentagonal (R/r=1.44), thickened.

Abactinal plates mostly hexagonal to rounded polygonal in outline proximally ( Fig. 1 B) with pentagonal and more irregularly shaped plates present distally. Each plate covered by ~40–60 (usually about 50) granules. Peripheral granules 17–30 pentagonal to quadrate in shape froming distinct linear periphery, with 4–6 granules on each plate side. Central granules 8–30 rounded, not angular, evenly distributed proximally to crowded distally. Shallow but distinct fasciolar groove present between abactinal plates. Papulae absent interradially. Madreporite hexagonal with moderately deep sulci, bordered by six abactinal plates. Abactinal granules large proximally becoming smaller and more densely packed distally adjacent to contact with superomarginal plate series.

Marginal plate series wide, 18 per interradius in each series ( Fig. 1 A). Correspondence between superomarginal and inferomarginal series is 1:1. Distal paired superomarginals, three to four pairs from terminal plate joined over midline with confluent peripheral granules but with largely bare plate surface ( Fig. 1 C). Superomarginals, convex in cross section, forming distinct dorsal-facing border and covered by small, round granules identical to those on abactinal surface covering lateral surface and surface of plate where bald spot is absent. Peripheral granules ~90–130 per side, round, 200–600 cover surface of superomarginal plate, evenly distributed. Prominent convex, bare spot, present on superomarginals occupying ~80% of dorsal-facing superomarginal plate series occupying more of plate surface distally ( Fig. 1 C). Inferomarginal plates lacking bare spot, completely covered by small, round granules. Inferomarginal forming convex contact with actinal plate surface. Actinal granules identical in size, distribution with those on inferomarginal plates urface. Terminal plate triangular, bare.

Actinal plates quadrate to triangular proximally, to irregular distally. Arranged in 7 discrete chevron rows, becoming more irregular adjacent to the inferomarginal plate contact. Actinal plates covered by round granules, 50–60 similar to those on abactinal surface ( Fig. 1 D, E). Peripheral granules approximately five to six per side, each with a discrete side. Actinal granules 15–30, within granular periphery, each round, evenly distributed proximally to more crowded distally adjacent to inferomarginal series.

Furrow spines five to six, exceptionally four (fig. 1E). Triangular to oval in cross-section, thick. Subambulacral spines three, round to quadrate in cross-section, similar in thickness and length to furrow spines. Adjacent rows, irregularly two, of adambulacral spines, granular, triangular to prismatic in cross-section, only 40–50% of height of subambulacral spines. Each row made up of three to six granular spines. Lower subambulacral granules separated from furrow+ subambulacral spines by distinct gap. Oral spines with eight to nine blunt furrow spines, thickened and similar to other furrow spines. Oral plate in each interradius divided in half by large gap filled with connective tissue. Each gap flanked by five spines/granules, each quadrate with sharp edges. Other spines/granules on oral plate similar, numbering five to six on oral plate. Two oral furrow spines per oral plate enlarged (total=4), triangular to angular in cross-section, projecting into mouth. Additional oral spines proximal to mouth opening also largest, adjacent to mouth.

Figures

FIGURE 1. Ceramaster patagonicus australis. USNM 1121579. A. Abactinal surface. B. Close-up of abactinal plates. C. Close-up of armtip showing superomarginal plate series. D. Actinal surface. E. Close-up of actinal surface showing mouth and furrow spination. Scale Bar = 0.5 cm.