Disasterina Perrier, 1875

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 : 19-20

Disasterina Perrier

Figures 2g , 5f , 10e–f , 12a–b

Disasterina Perrier, 1875: 289 .— Livingstone, 1933: 5–7.—H.L. Clark, 1946: 138.— Spencer and Wright, 1966: U69.—A.M. Clark, 1993: 218.— Liao and Clark, 1995: 131–132.— Rowe, 1995: 35.

Manasterina H.L. Clark, 1938: 157–158 .—H.L. Clark, 1946:

139.—A.M. Clark, 1993: 220.— Rowe, 1995: 36. New synonym.

Diagnosis. Rays 5; body thin, covered by thick integument; form medium to long-rayed stellate, rays with wide base, tapering strongly, flat actinally, height low convex; abactinal plates thin, on broad upper rays predominantly irregular in shape, size and arrangement, loosely imbricate or contiguous or not contiguous leaving non-plated spaces; plates on lower rays in few irregular longitudinal series, sometimes weakly notched and crescentiform; interradii thin distally, small non-papulate plates in perpendicular or zig-zag series to margin; papulae few, irregular on rays; abactinal spinelets lacking or rare or few, glassy, sacciform, short or long; superomarginal plates small, not in distinct series; inferomarginal plates project widely, loosely contiguous, with distal fringe of few large sacciform spinelets; actinal interradial plates in oblique series; proximal actinal interradial areas frequently not plated; interradial actinal plates with 1–2 long sacciform spines; superambulacral plates irregularly present mid-ray and distally, lacking complete series; superactinal plates present as single plate struts.

Type species. Disasterina abnormalis Perrier, 1875 (monotypy) (junior synonym: Habroporina pulchella H.L. Clark, 1921 , by Livingstone, 1933).

Other species. D. ceylanica Döderlein, 1888 ; D. longispina (H.L. Clark, 1938) ; D. odontacantha Liao, 1980 ; D. spinosa Koehler, 1910 .

Material examined. D. abnormalis . New Caledonia, AM J5042; Queensland, Cairns, J4947 (2); Hayman I., J5699 (1); J5904 (4); J5957 (1); J7315 (1); Torres Strait, Murray I., Z6748 (1); N Western Australia, Rowley Shoals, WAM Z6749 (2); Scott Reef, Z6753-5 (3).

D. longispina . Western Australia, Houtman Abrolhos, WAM Z6758 (1); Z6760 (2).

D. odontacantha . Fiji, UF 2391 (1); UF 1116 (1); UF, 1874 (1); Guam, UF 1253 (1).

Description with species variations. Body thin, rays 5 ( abnormalis 5–6); interradial margin deeply incurved, concave or acute proximally, form medium to long-rayed stellate; rays with wide base, tapering to narrowly or widely rounded end; body flat actinally, low convex abactinally; distal interradii wide and thin ( abnormalis ), or narrow and thin, rays rise distinctly from thin margin; body covered with thick integument; size medium ( abnormalis up to R = 38 mm) to small ( spinosa up to R = 14 mm); pedicellariae possibly present ( longispina ); none fissiparous.

Abactinal appearance irregular; abactinal plates on broad upper rays thin, irregular in form, size, arrangement; plates not distinguishable as primary and secondary, intergrade from large to small; plates weakly imbricating or contiguous or not contiguous leaving non-plated spaces on rays; lacking carinal series; plates on lower rays in few irregular longitudinal series; distal thin interradii with small rounded non-papulate plates in irregular series perpendicular or zig-zag to margin; plates on rays sometimes weakly notched for papulae and crescentiform ( spinosa ); papulae on rays only, single, few and sparse, large or small, irregular; disc not regularly bordered ( abnormalis ) or almost regular border ( longispina , odontacantha ); low domes sometimes present on abactinal plates ( longispina ); abactinal plates frequently bare, or with few sacciform spinelets around disc ( abnormalis ), or sometimes with 1–2 spinelets, short proximally, long distally ( odontacantha ), or with 1–4 spinelets variable in form from digitiform to long, pointed or rounded, principally on ends of rays ( longispina ), or with 1–3 long sacciform spinelets proximally and on rays ( spinosa ); clusters of 2–4 undifferentiated spinelets possibly act as pedicellariae interradially ( longispina ); glassy convexities present on abactinal plates ( abnormalis , longispina , odontacantha ); superomarginal plates small, not in distinct series, bare ( abnormalis , longispina ) or with 1 ( odontacantha ) or few long spinelets ( spinosa ); inferomarginal plates project prominently, some elongate and almost entirely projecting ( abnormalis , longispina , odontacantha ), each plate with transverse distal fringe of 1–6 integument-covered long sacciform spinelets.

Actinal interradial plates in oblique series; proximal actinal interradial areas frequently not plated.

Actinal spines per plate: oral 4–8; suboral 1–3 ( odontacantha 0); furrow 3–6 proximally, webbed; subambulacral 1–3; adradial bare ( abnormalis , odontacantha ) or with spines; actinal 1 or 2 ( spinosa ); interradial actinal spines long sacciform.

Superambulacral plates irregularly present mid-ray and distally ( abnormalis , longispina ), lacking complete series; superactinal plates present as single plate struts ( abnormalis , longispina ).

Distribution. Indo-West Pacific, South China Sea (Xisha Is), Ceylon, Bay of Bengal (Andaman Is), Indonesia, New Caledonia, Guam, Fiji, northern Australia, western Australia.

Remarks. Molecular data have not been obtained for species of Disasterina and the genus is reviewed on morphological grounds. Specimens of D. ceylanica and D. spinos a were not seen and morphological data were obtained from the original descriptions and figures by Döderlein (1888) and Koehler (1910).

Species previously assigned to Disasterina fall into two morphological groups, those close to the type D. abnormalis and retained here in Disasterina , and D. leptalacantha and D. praesignis (with junior synonym D. spinulifera ) which are close to Tegulaster emburyi and are removed to Tegulaster . Disasterina differs from Tegulaster in having: body thin and low, not thick and high; abactinal plates thin and loosely contiguous, not thick and imbricating; non-plated abactinal spaces present, not absent; median band of irregular abactinal plates on rays wide, not narrow; distal interradial plates at margin in irregular perpendicular series, not longitudinal and thus crossed angled series; superomarginal plates small and irregular, not large and in distinct series; covering integument thick, not thin. The form and patterns of spinelets and spines are similar in the two genera. Disasterina also shares some morphological characters with Indianastra gen. nov. below, in particular spination, limited presence of superambulacral plates and presence of series of superactinal plates. The morphological differences between Disasterina and Indianastra are detailed under the latter.

Manasterina longispina H.L. Clark, 1938 was described from a single specimen and the genus distinguished from Disasterina by size, single minute spinelets on some abactinal plates, long spinelets on rays distally, openly spaced abactinal plates, and absence of non-plated proximal actinal areas. None of these characters is of generic value. The long spinelets on distal ray plates is unique to the species. M. longispina is intermediate in size amongst species of Disasterina ; species of Disasterina sometimes have spinelets on abactinal plates; and the extent of non-plated abactinal and actinal body wall varies amongst specimens of M. longispina and amongst species of Disasterina . Manasterina is synonymised here with Disasterina . Clusters of 2–4 undifferentiated interradial spinelets with their distal ends angled together and contiguous were observed on preserved D. longispina material, and possibly act as pedicellariae.

Livingstone (1933) considered D. spinosa to be inappropriately assigned to Disasterina but gave no reason. The single long sacciform spinelets on abactinal plates distinguish the species but are not grounds for rejecting its generic placement. Disasterina ceylanica Döderlein (1888) was reassigned to Tegulaster by Livingstone (1933). Disasterina and Tegulaster have some common characters but the reassignment is inappropriate.

Material from the University of Florida extends the distribution of D. odontacantha from China to Guam and Fiji.

Figures

Figure 2. Abactinal views of type species of Asterinidae genera. a, Anseropoda placenta (R = 31 mm, AM J10714). b, Aquilonastra cepheus (R = 12 mm, AM J8072). c, Asterina gibbosa (R = 16 mm, AM G11524). d, Asterinides folium (R = 19 mm, USNM E28573). e, Callopatiria granifera (R = 50 mm, NMV F98049). f, Cryptasterina pentagona (R = 11 mm, NMV F95959). g, Disasterina abnormalis (R = 22 mm, WAM Z6754). h, Indianastra sarasini (R = 20 mm, NMV F95802). i, Meridiastra atyphoida (R = 12 mm, AM J9909). j, Nepanthia maculata (R = 73 mm, AM J13918). k, Paranepanthia platydisca (R = 57 mm, holotype, USNM 32644). l, Parvulastra exigua (R = 11 mm, neotype, TM H508).

Figure 5. Forms of spinelets and spines. a, Meridiastra gunnii (NMV F73248): granuliform abactinal spinelets. b, Parvulastra dyscrita (TM H854): globose abactinal spinelets. c, Paranepanthia grandis (NMV F73976): acicular abactinal spinelets. d, Pseudonepanthia gotoi (USNM 36899): splay-pointed abactinal spinelets. e, Parvulastra dyscrita (TM H854): digitiform actinal spines. f, Disasterina longispina (WAM Z6760): sacciform actinal spines.

Figure 10. a–d, Callopatiria granifera (R = 50 mm, NMV F98049); a, mid-ray abactinal primary and secondary plates, spinelets and papulae; b, internal superambulacral (left arrow) and superactinal (right arrow) plates; c, cleared lower lateral ray, with marginal plates, glassy convexities, papulae and secondary plates; d, section through ray showing superactinal (left arrow) and superambulacral (right arrow) plates. e, Disasterina abnormalis (R = 38 mm, WAM Z6749): integument-covered inferomarginal plate (arrow) with two distal sacciform spinelets. f, Disasterina longispina (R = 20 mm, WAM Z6760): abactinal tip of ray, with margin and long upper ray spinelet (arrow). g, Meridiastra atyphoida (R = 12 mm, NMV F87166): minute abactinal conical spinelets. h, Meridiastra occidens (R = 22 mm, NMV F73186): proximal actinal interradius, with oral spines. i, Meridiastra gunnii (R = 40 mm, NMV F73248): interradial margin supported by contiguous projections from abactinal and actinal plates, absence of superambulacral and superactinal plates.

Figure 12. Abactinal views of Disasterina species. a, Disasterina abnormalis (R = 11 mm, WAM Z6753). b, Disasterina longispina (R = 25 mm, WAM Z6760).