Ailsastra, O'Loughlin & Rowe, 2005

O'Loughlin, P. Mark & Rowe, Francis W. E., 2005, A new asterinid genus from the Indo-West Pacific region, including five new species (Echinodermata: Asteroidea: Asterinidae), Memoirs of Museum Victoria 62 (2), pp. 181-189 : 182

Ailsastra gen. nov.

Figure 1

Type species. Ailsastra paulayi sp. nov.

Other included species. Ailsastra achituvi sp. nov.; A. amezianeae sp. nov.; A. booneni sp. nov.; A. eleaumei sp. nov.; Asterina heteractis H.L. Clark, 1938 .

Diagnosis. Small, stellate asterinids, up to R = 16 mm; rays predominantly 5; one species fissiparous (5–7 rays); interradial margin incurved, rays discrete, broad to narrow at base, short to long, rounded distally; flat actinally, convex abactinally, inferomarginal plates project to form acute ventrolateral margin; disc distinctly to irregularly defined; carinal series of plates present for most of ray, doubly papulate with 2 longitudinal series of large papulae for most of ray, each plate with rounded anterior projection; carinal plates imbricated by adcarinal plates on both sides, forming characteristic ‘sunken’ series; other abactinal plates closely imbricate, not notched, arched over papular space more than indented proximally for papula; lacking secondary plates; papulae on rays single per papular space, large, in longitudinal series; spinelets glassy, thick to thin, conical or sacciform or subsacciform, pointed or splay-pointed, in clusters or single or double series across proximal plates, sometimes in round or oval bowl-shaped series on plate; lacking pedicellariae with differentiated valves; plates with prominent glassy convexities; superomarginal and inferomarginal plates in regular series; actinal interradial plates in predominantly oblique series; oral plates distinctively small, constricted distally (pair with form of short-handled, smooth-headed mace or club); oral spines up to 6, series incurved distally; suboral spines variably present, if present in continuous series with distal oral spines; lacking superambulacral and superactinal plates in type species and two other investigated species .

Distribution. Lord Howe I., NE Australia, Sulawesi I., Sudanese Red Sea, Mauritius, NW Madagascar; rock and coral; 0– 16 m.

Etymology. From Ailsa with the Latin astrum (star), in recognition of the substantial contribution by Ailsa Clark to seastar systematics (feminine).

Remarks. Superambulacral and superactinal plates are absent from the type species A. paulayi , and A. amezianeae and A. eleaumei . The remaining three species (which have not been dissected) have the other generic characters of Ailsastra , and it is anticipated that they too lack these internal plates. Ailsastra shares the lack of superambulacral and superactinal plates with seven other genera currently included in the Asterinidae : Asterina , Asterinides , Kampylaster , Meridiastra , Pseudasterina , Pseudopatiria and Tremaster (see O’Loughlin and Waters, 2004). However, the form of the oral plates and arrangement of the carinal series of plates distinguish Ailsastra , morphologically, from these and all other genera in the family. The morphological justification for recognising the new genus is supported by limited molecular data that places the two specimens of the type-species A. paulayi sp. nov. (see below) in a highly divergent but strongly monophyletic clade within a molecular phylogeny of Asterinidae (Jon Waters, pers. comm.; paper in preparation).

Figures

Figure 1. Distributions of the type localities of the six species of Ailsastra gen. nov.