Indianastra O’Loughlin, 2004

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 : 20-22

Indianastra O’Loughlin gen. nov.

Figures 2h , 6b , 13a–f

Diagnosis. Rays 5, petaloid to subpentagonal; size small; body thin, integument-covered; abactinal and actinal interradial plates in longitudinal series; abactinal plates deeply notched for papulae, short crescentiform; numerous regular longitudinal series of plates with papulae along sides of rays; abactinal spinelets fine, glassy, inconspicuous, acicular to subsacciform, few to numerous per plate, in tufts or cover over plate, not on high raised ridges or domes, fragile, readily lost; pedicellariae sometimes present over papulae; superomarginal plates with rare spinelets or bare; inferomarginal plates with distal subpaxilliform dense tufts of acicular spinelets, covered by integument; actinal interradial plates in longitudinal series; plates with small clusters of webbed short sacciform spines; lacking superambulacral series of plates, rare single plates distally; superactinal plates as single plate struts.

Type species. Palmipes sarasini de Loriol, 1897 (junior synonyms: Asterina lutea H.L. Clark, 1938 , Asterina nuda H.L. Clark, 1921 , and Asterina orthodon Fisher, 1922 by Rowe, 1995).

Other species. I. inopinata ( Livingstone, 1933) (junior synonym: Asterina perplexa H.L. Clark, 1938 , by Rowe, 1995).

Material examined. I. inopinata . Holotype, 12 paratypes. Australia, New South Wales, AM J3077 . Other material. New South Wales, NMV F93460 (3) ; Byron Bay , AM J15254 (6);

I. lutea . Paratypes. NW Australia, Broome , AM J6167 (4).

I. orthodon . Hong Kong, BMNH 1983.2.15.116 (1).

I. sarasini . NW Australia, WAM Z6833 (1); Broome, AM J6640 (5); NMV F95802 (2); Queensland, J4123 (1).

Description with species variations. Rays 5, petaloid (rays wide basally, rounded distally, subacute to narrowly rounded junctions) to narrowing rounded to subpentagonal (interradial margin straight to shallow incurved); body integument-covered, flat actinally, low convex abactinally; size small (both species up to R = 20 mm); simple pedicellariae present over papulae, valves short, conical to sacciform, up to 6 valves ( sarasini only); not fissiparous.

Abactinal appearance dominated by numerous regular longitudinal series of papulae along sides of rays; plates imbricate, deeply notched for papulae, interradially in longitudinal series to margin; papulate areas extensive, papular spaces fairly large, predominantly single large papula per space, up to 4 small papulae and 5 secondary plates per space; up to 6 longitudinal series of papulae along each side of rays; plates on narrow median upper rays irregular, carinal series of plates variably present, doubly notched; abactinal plates with low spinelet-bearing elevations, on lower rays and proximal interradii predominantly singly notched for papulae, crescentiform only ( inopinata ), additional deep to almost closed pedicellarial notch proximally ( sarasini ); fine, glassy, fragile, inconspicuous, acicular to subsacciform spinelets, sparsely present in apical tufts or numerous in crescentiform cover on projecting proximal edge of plates, spinelets readily lost; glassy convexities (sarsini) or reticulations ( inopinata ) on plates; disc variably bordered by continuous series of 5 large radial 5 small interradial plates; superomarginal plates in series, rare spinelets ( inopinata ) or bare ( sarasini ); inferomarginal plates in series, project to form margin, bare proximally, distal subpaxilliform dense tuft of acicular spinelets projects laterally, integument-covered.

Actinal plates in longitudinal series.

Actinal spines per plate (lower numbers in inopinata ): oral 8–11; suboral 4–9, webbed fan; furrow 5–9 proximally, webbed; subambulacral 3–9; adradial actinal plates with complete series; actinal 2–8 in mid interradius, webbed transverse clusters; actinal interradial spines short sacciform.

Lacking series of superambulacral plates, rare single plates distally (seen in sarasini only); margin supported by series of single superactinal plates, and internal tongue-like projections of abactinal plates contiguous with actinal plates.

Distribution. Indian West Pacific, Sri Lanka to southern China, N and E Australia, 0– 25 m.

Etymology. From the first word of “Indian West Pacific” and the Latin astrum (star), referring to the region of occurrence of this genus (feminine).

Remarks. Molecular data are not available for either species and this review is based on morphological evidence. Indianastra shares some morphological characters with both Disasterina and Tegulaster , in particular the spination, limited presence of superambulacral plates and presence of series of superactinal plates. Morphological differences between Indianastra and Disasterina are: form petaloid to subpentagonal, or rays discrete; abactinal plates small, of uniform size and imbricate, or irregular in size, form and arrangement and loosely contiguous; abactinal plates deeply, or slightly notched; longitudinal series of papulate plates numerous and regular on rays, or few and irregular on lower sides of rays; abactinal interradial plates in longitudinal series, or series perpendicular to margin; superomarginal series of plates distinct and regular, or reduced and irregular; inferomarginal spinelets acicular, in dense tufts, or few, sacciform and discrete; actinal series of plates longitudinal, or oblique; actinal interradial spines short, in clusters, or long, 1–2. Morphological differences with Tegulaster are given under Tegulaster below. These morphological differences are the basis for the erection of the new genus.

Jangoux (1985) established a lectotype and paralectotype for Palmipes sarasini . Rowe (1995) formalised the synonymies of I. lutea , I. nuda and I. orthodon with I. sarasini , which had been suggested by Clark and Rowe (1971). Dartnall (1970, 1980) recorded A. inopinata from northern Tasmania, but records were based on material subsequently determined by O’Loughlin as Meridiastra nigranota O’Loughlin, 2002 (TM H1330), M. atyphoida (H.L. Clark, 1916) (TM H841) and Asterina scobinata Livingstone, 1933 (TM H1746). The pedicellariae on I. sarasini are frequently difficult to detect because the valves are lost or close over the notch and are integument-covered.

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 6. Forms of abactinal fasciculate pedicellariae. a, Asterina ocellifera (BMNH 1969.12.16.13). b, Indianastra sarasini (WAM Z6836). c, Nepanthia belcheri (NMV F95805).

Figure 13. a, Indianastra inopinata (R = 19 mm, AM J15254): cleared abactinal surface. b–f, Indianastra sarasini (R = 14 mm, WAM Z6835): b, abactinal ray; c, abactinal elongate subsacciform spinelets, and papulae; d, bare superomarginal plates, and tufts of inferomarginal spinelets; e, oral and proximal actinal spines; f, actinal plates and spines.