Tegulaster leptalacantha (H.L. Clark, 1916)

Figure 5a–f

Asterina leptalacantha H.L. Clark, 1916: 57–58, pl. 18 figs. 3–4.

Disasterina leptalacantha.— Livingstone, 1933: 6, 8–10, pl. 3 figs. 5–6, pl. 4 figs. 1, 4.—H.L. Clark, 1946: 139.—A.M. Clark and Rowe, 1971: 38–39, 67.— Rowe and Gates, 1995: 36.

Disasterina leptalacantha var africana Mortensen, 1933: 259–260, pl.12 fig. 3.—A.M. Clark and Courtman-Stock, 1976: 78.

Tegulaster leptalacantha.— O’Loughlin and Waters, 2004: 13, 35–36.

Material examined. Disasterina leptalacantha. Holotype: NE Australia, Queensland, Capricorn Group, Masthead I., littoral, Dec 1913, AM J3082.

Disasterina leptalacantha var africana. Syntype: South Africa, Natal, off Tugela River, 366 m, S.A.M. A22559 (1).

Other material. NE Queensland, AM J6097 (1); AM J12488 (1); Indian Ocean, Mauritius I., Cape Malheureux, down to 24 m, UF 2499 (1); La Réunion I., Saint Leu, C. Conand, 22 Mar 2003, NMV F109364 (3); NMV F109367 (4); S Madagascar, Mission Decary, MNHN EcAs 11856 (1); E South Africa, Sodwana Bay, 11 m, MRAC 1746 (1); 14 m, MRAC 1744 (2); Trafalgar Marine Reserve, 14 m, MRAC 1745 (1).

Description. Thick integument body cover; rays 5, discrete, medium length, wide base, tapered, blunt to narrowly rounded distally, elevated, steep sides, acute thin margin, up to R = 24.5 mm; single madreporite; abactinal gonopores; superambulacral and superactinal plates present.

Abactinal: plates predominantly bare, thick, frequently with raised domes, generally closely imbricate, rarely spaced creating non-plated areas, upper ray plates irregular in size, form, arrangement, regular longitudinal series along sides of rays, lower ray plates indented proximally for papula; lacking distinct secondary plates; papulae large, single, irregular along upper ray, sometimes doubly papulate carinal plates mid-ray, up to 3 longitudinal series long each side of ray, up to 8 longitudinal series across mid-ray; disc variably bordered by 5 radial, 5 interradial plates; small subsacciform spinelets sometimes present perianally, on disc, around madreporite; long acicular spinelets sometimes on distal interradii; up to few small granular or subsacciform or conical spinelets on abactinal plates of small specimens (R = 5 mm); glassy convexities on plates.

Margin: superomarginal plates of variable size and regularity as series, bare except small specimens with single, small, conical glassy spinelets; inferomarginal plates project, plates sometimes with constricted waist, distal tuft of up to 10 and more glassy, long, acicular subsacciform spinelets, up to 1.5 mm long.

Actinal: interradial plates in oblique series. Actinal spines per plate: oral 8–9, strongly tapered series; suboral 1 (sometimes small additional distal one); furrow 5, short; subambulacral 1, long; adradial actinal 1; actinal interradial 1; spines long, tapering to thin, sacciform.

Distribution. NE Australia, Mauritius I., La Réunion Is., Madagascar, E South Africa, 0– 366 m.

Remarks. Mortensen (1933) observed only minor morphological differences between the type and the two South Africa specimens on which he based his variety. Amongst these differences he noted that there were only five oral spines in the type, but seven in the variety. The type has eight oral spines, and eight and nine were observed on the specimen of the variety from Natal. Mortensen (1933) erected the variety “mainly for zoogeographical reasons” since the type locality for Tegulaster leptalacantha is Queensland (NE Australia). In O’Loughlin and Waters (2004) I determined material from Mauritius as T. leptalacantha, and judged that the variety was not justified. I confirm that opinion here. In O’Loughlin and Waters (2004) I reassigned Disasterina leptalacantha to Tegulaster Livingsone, 1933. I confirm the morphological grounds for the reassignment here. The diagnostic characteristics of Tegulasterleptalacantha are: 5 discrete, high, tapered rays; thick integument evident over body; predominantly bare abactinal plates; abactinal plates frequently with rounded domes; actinal plates in oblique series; single long sacciform spines on each actinal interradial plate; inferomarginal plates with distal dense tufts of long, glassy, acicular subsacciform spinelets; superambulacral and superactinal plates present.

Tegulaster leptalacantha is distinguished from all other species of Tegulaster byhavingatuftoflongacicularsacciform spinelets on each inferomarginal plate; and is also distinguished in particular from T. emburyi Livingstone, 1933 (type species for Tegulaster; type locality Queensland) by having single suboral and actinal interradial spines per plate, from T. alba (H.L. Clark, 1938) (type locality Lord Howe I.) by having abactinal gonopores, and from T. praesignis (Livingstone, 1933) (typelocalityQueensland) byhavingbaresuperomarginal plates (see O’Loughlin and Waters, 2004 for these and other distinguishing characters).