Tegulaster Livingstone, 1933

O’Loughlin, P. Mark & Waters, Jonathan M., 2004, A molecular and morphological revision of genera of Asterinidae (Echinodermata: Asteroidea), Memoirs of Museum Victoria 61 (1), pp. 1-40 : 35-36

Tegulaster Livingstone

Figures 3f , 18a–b

Tegulaster Livingstone, 1933: 11–12 .—H.L. Clark, 1946: 143.— Spencer and Wright, 1966: U69.— A.M. Clark, 1993: 228.— Rowe, 1995: 41.

Diagnosis. Rays 5, size small, body thick, covered by thin integument; rays discrete, form medium to long-rayed stellate, flat actinally, rays elevated, narrow or broad basally; abactinal plates thick, imbricating, shallow notch and crescentiform, irregular in form and arrangement on narrow median band of upper rays; plates and papulae in few series along sides of rays; papulae predominantly single per space; secondary plates rare; abactinal spinelets few to none on plates, glassy, sacciform or conical or acicular; glassy convexities present; superomarginal plates in regular series; inferomarginal plates each with up to 7 discrete short spinelets or tuft of acicular spinelets; actinal interradial plates in oblique series; actinal interradial plates each with 1–2, long or short, sacciform spines; superambulacral plates rare, or in distal series, not in complete series; superactinal plates present as single plate struts.

Type species. Tegulaster emburyi Livingstone, 1933 (original designation).

Other species. T. alba (H.L. Clark, 1938) ; T. leptalacantha (H.L. Clark, 1916) (unrecognised subspecies: Disasterina leptalacantha africana Mortensen, 1933 , this work); T. praesignis ( Livingstone, 1933) (junior synonym: Disasterina spinulifera H.L. Clark, 1938 , this work).

Material examined. Asterina alba . Paratypes. Lord Howe I., AM J6170 (5) ; NMV F45118 (2). Other material. J16575 (1).

T. emburyi . Holotype. Capricorn Group , Queensland, shallow sublittoral, AM J5605 .

Asterina leptalacantha . Holotype. Queensland, Capricorn Group, AM J3082 . Other material. J6097 (1); Mauritius, 24 m, UF 2499 (1).

Disasterina praesignis . Holotype. Queensland, Port Curtis , AM J5059 . Other material. J19314 (3); NMV F94009 (1) ; F94010 (1).

D. spinulifera . N Western Australia, Lacepede I., WAM Z6773 (1).

Description with species variations. Body thick, covered by thin integument; rays 5, discrete, flat actinally, high convex abactinally, narrow at base ( emburyi ) or broad basally tapering distally to widely ( alba ) or narrowly ( leptalacantha , praesignis ) rounded; size small ( leptalacantha up to R = 25 mm; alba up to R = 7 mm); pedicellariae present over papulae ( emburyi , 2 conical valves), or not; none fissiparous; gonopores abactinal or actinal ( alba ).

Abactinal surface uneven, dominated by projecting proximal edges of imbricating thick plates; narrow median band of upper rays plates irregular in form and arrangement; part carinal series variably evident on upper rays ( alba , emburyi , praesignis ); secondary plates rare ( emburyi ) or absent ( alba ), or primary plates grading from large to small ( leptalacantha , praesignis ); up to 3 series of papulate plates with shallow notch and crescentiform along each side of rays; papular spaces small, predominantly single large papulae per space, irregular on upper rays, series on sides of rays; disc bordered by 5 radial and 5 interradial plates, variably regular; abactinal plates with spinelet-bearing raised rounded proximal edge ( alba ) or domes ( leptalacantha ); abactinal spinelets frequently lacking, or sometimes up to 12, glassy, sacciform to conical, spinelets across proximal edge of plates ( alba ), or present distally as tufts of small sacciform spinelets ( emburyi ), or with tufts of acicular sacciform spinelets on distal interradial plates ( leptalacantha ), or rarely a few short sacciform spinelets on apex of plates ( praesignis ); glassy convexities on bare plates; superomarginal and inferomarginal plates predominantly subequal, in regular series; superomarginal plates with a few abactinal-type spinelets ( alba ), or with spinelets only in mid-interradius ( emburyi ), or bare ( leptalacantha ), or with rare spinelets ( praesignis ); projecting inferomarginal plates with cover of up to 7 short acicular spinelets per plate ( alba ), or series of up to 6 short spinelets ( emburyi , praesignis ), or tuft of long acicular sacciform spinelets ( leptalacantha ).

Actinal interradial plates in oblique series; proximal interradial non-plated areas sometimes present ( leptalacantha , praesignis ).

Actinal spines per plate: oral 6–9; suboral 1 ( alba , leptalacantha , praesignis ) or 2 large, 4 small ( emburyi ); furrow 4–7, webbed; subambulacral 1–5; adradial actinal spines present; actinal predominantly 2 ( emburyi ) or 1; actinal interradial spines sacciform, long or short ( alba ).

Superambulacral plates rare ( alba , emburyi ) or series distally ( leptalacantha , praesignis ), not in complete series; superactinal plates present as single plate struts.

Distribution. Northern Australia, Lord Howe I., Norfolk I., Mauritius, South Africa; 0– 366 m.

Remarks. Molecular data are not available and this review is based on morphological evidence. Two species have been removed from Disasterina to Tegulaster and the reasons are discussed under the former. Tegulaster also shares some morphological characters with Indianastra gen. nov. above, in particular the spination, limited presence of superambulacral plates and presence of series of superactinal plates. The features distinguishing Tegulaster from Indianastra are: body thick with discrete rays, not thin with petaloid to subpentagonal form; abactinal plates large thick in few irregular series along sides of rays, not small thin in numerous regular series along rays; abactinal plates at most slightly notched and crescentiform, not deeply notched; inferomarginal spinelets discrete, not acicular in dense integument-covered tufts; actinal interradial spines per plate up to 2, not small webbed fans; actinal interradial plates in oblique series, not longitudinal series.

Livingstone (1933) established D. praesignis for a single specimen (R = 14 mm) from Port Curtis (NE Australia). H.L. Clark (1938) established D. spinulifera for a single specimen (R = 8 mm) from Broome (NW Australia), and did not distinguish it from D. praesignis . Specimens of both species were compared and found to be identical; D. spinulifera is a junior synonym of D. praesignis . Asterina alba has all the diagnostic characters of Tegulaster . Livingstone (1933) assigned Disasterina ceylanica to his new genus Tegulaster but it has the characters of Disasterina . D. leptalacantha var. africana was established by Mortensen (1933) on the basis of its geographical separation ( South Africa) from the D. leptalacantha type locality (NE Australia). Material from Mauritius has been determined as T. leptalacantha and no evidence found to justify the retention of variety africana .

Figures

Figure 3. Abactinal views of type species of Asterinidae genera (continued; Tremaster mirabilis is figure 17e). a, Patiria miniata (R = 67 mm, NMV F98040). b, Patiriella regularis (R = 31 mm, AM J5594). c, Pseudonepanthia gotoi (R = 74 mm, holotype, USNM 36899). d, Pseudopatiria obtusa (R = 54 mm, holotype, BMNH 1938.6.23.24). e, Stegnaster inflatus (R = 45 mm, NMV F95675). f, Tegulaster emburyi (R = 19 mm, holotype, AM J5605).