Aquilonastra samyni, O, 2006

O, P. Mark, 2006, A systematic revision of the asterinid genus Aquilonastra O Loughlin, 2004 (Echinodermata: Asteroidea), Memoirs of Museum Victoria 63 (2), pp. 257-287 : 282-283

Aquilonastra samyni sp. nov.

Figures 1, 3g, h, 6j, 10d

Material examined. Holotype. Oman, Masirah I., 1–7 m, under rocks, G. Paulay, 6 Nov 1999, UF 246 (alcohol).

Paratypes. Type locality, 15–18 m, G. Paulay, 5 Nov 1999, UF 68 (8, alcohol) ; Bar al Hikman, under rocks, 0–1 m, M. Bouchard, 7 Nov 1999, UF 1645 (2).

Other material. Oman, Bar al Hikman peninsula, 1–3 m, under rocks, 18–20 Jan 2005, UF 4210 (2) ; 2–3 m, UF 4201 (3) ; 2–4 m, under rocks, Jan 2005, UF 4143 (3) ; Muscat, Qurm , intertidal, 26 Jan 2005, UF 4147 (6) ; UF 4251 (1) ; UF 4252 (1) ; Bandar Khayran , under rocks, 0–5 m, 29 Oct 1999, UF 1378 (1) ; Madagascar, MNHN EcAs 11853 (1); NW Madagascar, Nossi Be (Nosi Bé), littoral reef, 24 Sep 1964, EcAs11848 (1); 2 Dec 1959, EcAs11849 (5); 1962, EcAs11850 (1); 6 Oct 1959, EcAs11851 (3); 3 Dec 1959, EcAs11852 (2); SW Madagascar, Tuléar , EcAs 11847 (1); Ile Sainte-Marie, 11 Feb 1979, WAM Z6870 (2) ; La Réunion I., Tobogan , 10 Sep 2001, NMV F109365 (1) ; South Africa, Sodwana Bay , 10 m, Jul 2000, MRAC 1741 (1) ; 13 m, Aug 1999, MRAC 1740 (1) ; MRAC 1743 (1) ; Bangha Nek , 16 m, Aug 1999, MRAC 1742 (1).

Diagnosis. Non-fissiparous Aquilonastra species; rays predominantly 5, rarely 6, narrow basally, slight taper, rounded distally, subdigitiform, up to R = 27 mm, r = 11 mm; single conspicuous madreporite, 2 rare, 3 very rare; gonopores abactinal.

At R = 23 mm, r = 9 mm, 0–3 proximal doubly papulate carinal plates; disc frequently well-delineated by 5 radial 5 interradial plates; up to about 30 spinelets in irregular double transverse series across proximal abactinal plates, some spinelets in poorly defined clusters (spinelets granuliform on small specimens); 0–2 secondary plates per papular space proximally, rarely 2 papulae per space; spinelets small, short, thick, conical to columnar, sometimes splay-pointed, sometimes with long thin distal point; up to about 14 on distal interradial plates, not overlapping adjacent plate spinelets if splayed; superomarginal plates smaller than inferomarginals, superomarginals with up to about 12 spinelets per plate, inferomarginals with up to about 24 larger spinelets per plate.

Spines per actinal plate up to: oral 8, suboral 6, furrow 7, subambulacral 8, actinal interradial 14, predominantly 8–12; interradial spines short, thick, rugose, sacciform, bluntly conical (lower spine numbers per plate on South Africa material).

Colour (live). Variable; disc white, apically around disc bright red, rays mottled mauve, brownish-red, off-white, brown (photos from G. Paulay and Y. Samyn).

Distribution. Oman (Masirah I.); Madagascar; La Réunion I.; E South Africa (Sodwana Bay); 0– 18 m.

Etymology. Named for Yves Samyn, of the Royal Belgian Institute of Natural Sciences, for his contribution of specimens used in this work and in appreciation of his research on echinoderm systematics.

Remarks. Pentaradiate, single madreporite, non-fissiparous specimens as small as R = 6 mm have been examined, evidence that this species does not have a small pluriradiate fissiparous growth stage. Large specimens have mostly come from the deeper sublittoral (3–18 m), while the numerous small specimens have mostly come from the intertidal and shallow sublittoral (0–2 m). If this species occurs in deeper sublittoral habitats this might account for the absence of the species in collections from most of the eastern African coast. It might also account for the absence of large specimens from Madagascar, as the collecting appears to have been littoral.

A. samyni is morphologically similar to A. marshae (above), but is distinguished from A. marshae (characters in brackets) by: rays long, mostly subdigitiform, only slightly tapered (not short, mostly strongly tapered); abactinal surface is predominantly flat (plates not raised proximally and angled over papulae); spinelets are predominantly spread over plate surface (not predominantly concentrated over raised proximal plate edge); distal plate surfaces with spread spinelets (not bare with 1–2 central spinelets); at R = 16 mm, predominantly 6 spines per actinal plate (not 3); actinal spines short, blunt, sacciform (not conical to digitiform).

For population studies by Soliman (1995, 1999) see Remarks under A. burtonii above.