Aquilonastra shirleyae, O'Loughlin, 2009

O'Loughlin, P. Mark, 2009, New asterinid species from Africa and Australia (Echinodermata: Asteroidea: Asterinidae), Memoirs of Museum Victoria 66 (2), pp. 203-213 : 204

Aquilonastra shirleyae sp. nov.

Figure 1a–f

Material examined. Holotype: Western Australia, Point Cloates, 22°50'55" S, 113°30'39" E to 22°51'29" S, 113°30'50" E, 100 m, Southern Surveyor , SS 10/2005 stn 135, M.P. Salotti and S. Slack-Smith, 9 Dec 2005, WAM Z37278 .

Paratype: Red Bluff, 24°02'37" S, 113°01'37" E to 24°02'50" S, 113°01'44" E, 100 m, Southern Surveyor , SS 10/2005 stn 126, M.P. Salotti and S. Slack-Smith, 8 Dec 2005, WAM Z37279 (1, denuded) .

Description. Small, stellate, R = 13 mm, r = 5 mm (holotype; abnormal abactinal digitiform growth near disc), R = 8 mm, r = 4 mm (paratype; 2 rays regenerating); 5 sub-equal discrete rays, subdigitiform, interradial margin deeply incurved; rays tapering to narrow rounded distal end; rays flat actinally, high domed elevation abactinally; body integument not evident; single madreporite; not fissiparous; gonopores abactinal; glassy convexities on plates; superambulacral and superactinal plates present internally.

Abactinal: disc not discretely defined; rare proximal doubly or singly papulate carinal plates on holotype, weakly developed singly papulate carinal series on paratype, remaining upper ray plates irregular in arrangement; non-carinal plates crescentiform with single notch for papula; papular spaces small, single papula per space; 3 longitudinal series of singly papulate plates along each side of rays; rare secondary plates except in disc area; large white opaque bi-valved pedicellariae over papulae on upper sides of rays of holotype, less developed on small paratype; spinelets glassy, conical or columnar, up to about 0.15 mm long, tapered or splay-pointed distally, rugose, in splayed clusters on plates, in 3 small clusters across rare doubly papulate carinal plates, up to about 25 spinelets per plate; ends of distal abactinal interradial splayed spinelets rarely overlap ends of adjacent plate spinelets.

Margin: superomarginal plates about half size of inferomarginal plates, both in regular series; up to about 16 spinelets on both superomarginal and inferomarginal plates, thicker on inferomarginals.

Actinal: plates in longitudinal series, parallel to furrow; complete series of adradial actinal plates and spines. Actinal spines per plate: oral 8–10, suboral 7–9, ambulacral / furrow 7–8, subambulacral 7–8, proximal actinal 7–10, distal actinal, 7–10; oral spines digitiform, rugose; other actinal spines thin, glassy, rugose, pointed distally.

Colour. Live (photo of paratype): abactinal pale mottled with white, pale brown, pale orange; actinal white.

Preserved: white.

Distribution. Western Australia, Point Cloates, Red Bluff, continental shelf, 22– 24° S, 113° E, 100 m.

Etymology. Named for Shirley Slack-Smith of the Western Australian Museum, with appreciation of her role in collecting these specimens, and in recognition of four decades of dedicated contribution to Australian marine mollusc research.

Remarks. The new species has the diagnostic characters of genus Aquilonastra O’Loughlin as detailed in the emended diagnosis by O’Loughlin and Rowe (2006): discrete rays, interradial margin deeply incurved, stellate; high domed abactinally, flat actinally; abactinal plates predominantly irregular in arrangement on upper rays; longitudinal series along sides of rays, not perpendicular to margin; predominantly single papular notch per plate; predominantly single papula per papular space; numerous elongate glassy spinelets on each abactinal plate; superomarginal and inferomarginal plates in regular series; suboral spines present; adradial actinal spines in complete series; superambulacral and superactinal plates present internally.

A key to the 24 species of Aquilonatra is provided by O’Loughlin and Rowe (2006). Aquilonastra shirleyae sp. nov. is close diagnostically to Aquilonastra rowleyi O’Loughlin and Rowe, 2006 (Sodwana Bay, SE Africa) and Aquilonastra watersi O’Loughlin and Rowe, 2006 (Arabian and Red Seas, and western Indian Ocean). Aquilonastra shirleyae is distinguished from Aquilonastra rowleyi (details in brackets) by: size (up to R = 23 mm); subdigitiform rays (rays short, wide at base; fig. 6i in O’Loughlin and Rowe, 2006); pedicellariae squat (elongate; fig. 10c in O’Loughlin and Rowe, 2006); disc not discretely defined (disc clearly bordered; fig. 10b in O’Loughlin and Rowe, 2006); superomarginal plates half size of inferomarginals (subequal); actinal interradial spines 7 – 10 (3–4).

Aquilonastra shirleyae is distinguished from Aquilonastra watersi (details in bracket) by: size (up to R = 19 mm); rays that are thinner, with narrower base (rays short with wide base; figs. 3j, 10e in O’Loughlin and Rowe, 2006); few singly and doubly papulate carinal plates (up to 10 doubly papulate); up to about 25 abactinal spinelets per plate (up to about 20); pedicellariae conspicuous (inconspicuous; fig. 6l in O’Loughlin and Rowe, 2006); up to about 16 superomarginal spinelets per plate (up to about 7); up to 10 actinal spines per plate (up to 8); mottled very pale white, pale brown, pale orange (mottled pale brown, red-brown, grey-brown, blue-grey; off-white; fig. 3j in O’Loughlin and Rowe, 2006).

O’Loughlin and Rowe (2006) reported most Aquilonastra species from the shallow sub-littoral to about 50 m. A. batheri (from Japan) was reported to 92 m, and A. cepheus (from southern China to northern Australia) to 70 m. A. rosea (SW Australia) was reported to 110 m, the only occurrence deeper than A. shirleyae .

Figures

Figure 1. Aquilonastra shirleyae sp. nov. (photos by L. Altoff and A. Falconer). Holotype, WAM Z37278 (R = 13 mm; all except b); paratype WAM Z37279 (R = 8 mm; cleared; b only). a, abactinal surface (one ray dissected off; abnormal digitiform growth arrowed). b, disc not discretely defined; few proximal carinal plates with single papula arrowed. c, abactinal pedicellariae (arrowed) and spinelets on upper side of ray. d, section through cleared ray showing superambulacral plates (right arrow) and superactinal plates (left arrow). e, actinal surface with actinal plates in longitudinal series. f, oral, suboral, furrow, subambulacral and proximal actinal spines.