Aquilonastra alisonae, O’Loughlin, 2015

O’Loughlin, P. Mark, 2015, New asterinid seastars from northwest Australia, with a revised key to Aquilonastra species (Echinodermata: Asteroidea), Memoirs of Museum Victoria 73, pp. 27-40 : 30-35

Aquilonastra alisonae sp. nov.

Zoobank LSID. http://zoobank.org/ urn:lsid:zoobank.org:act:

727C2763-A5B6-463A-B184-94572BD2B4F5

Material examined. Holotype. North Western Australia, Kimberley Region, Woodside Collection Project (Kimberley) 2008–2015, station 56/K10, Long Reef , 13.95704 S - 125.71846 E, rock substrate, intertidal, coll. A. Sampey et al., 24 Oct 2010, WAM Z26200 (one ray abnormal; one ray cut off mid-ray and cleared).

Paratype. Woodside Collection Project (Kimberley) 2008–2015, station 47/K10, Long Reef, 13.81995 S - 125.74942 E, rock substrate, fore reef, 6 m, coll. S. Woolley, 21 Oct 2010, WAM Z26199 (1).

Description. Asterinid seastar, six rays, variably slightly unequal, rays wide basally, tapered to rounded end distally, up to R = 6.2 mm, r = 3.0 mm, rays merging at bases, inter-radial junction of rays sub-acute, rays low convex abactinally, rays flat actinally, margin acute. Madreporite large, conspicuous, only one detected on holotype, above junction of bases of two rays. Not fissiparous. Disc not discretely demarcated. No abactinal or actinal gonopores detected. Pedicellariae not detected. Glassy convexities on cleared abactinal and actinal plates. Superomarginal and inferomarginal plates subequal; inferomarginal plates not projecting noticeably. Internal superambulacral and superactinal plates present.

Abactinal surface: disc plates imbricate irregularly with those of rays; upper ray plates irregular in form, not in regular series, no carinal series of plates; most upper ray plates widely concave proximally to create papular space; single papula per papular space; rare secondary plates; 4 prominent longitudinal series of papulae across rays, short lower series of smaller papulae along rays, up to 11 papulae per series along upper ray, series along upper part of ray irregular; up to about 10 predominantly splay-pointed spinelets per abactinal plate, frequently in 2 transverse series across proximal edge and middle of plate; superomarginal plates with up to 8 splay-pointed spinelets per plate in 2 series of 5 distal and 3 proximal.

Actinal surface spines per plate: oral 6, long, thin, slightly cylindrical to spatulate; sub-oral 4–3; furrow 5, digitiform; subambulacral 4, digitiform to splay-pointed; actinal up to 7 on central plates, conical to splay-pointed; inferomarginal up to about 9, predominantly splay-pointed, frequently with 6 abactinal inferomarginal, 3 actinal inferomarginal. Actinal inter-radial plates in slightly irregular longitudinal and oblique series.

Distribution. North Western Australia, Kimberley Region, Long Reef, rock substrate, 0– 6 m.

Etymology. Named for Alison Sampey, formerly of WAM, who initially collected and curated these specimens.

Remarks. The slightly irregular length of the six rays and irregular plate arrangement on disc and upper rays prompted us to think initially that this species is fissiparous. But the presence of only one conspicuous madreporite, and only slight ray length differences lead us to judge that the species is not fissiparous, at least for the size of the two type specimens. Aquilonastra alisonae sp. nov. is distinguished diagnostically from other Aquilonastra species in the key. It differs in particular from other species of Aquilonastra from the Kimberley region by having a combination of: six rays; predominantly splay-pointed abactinal spinelets; singlemadreporite;non-fissiparoushabit;absenceofpedicellariae. We did not observe gonopores, but they were clearly not present actinally and assume that they would be abactinal if present.