Aquilonastra starmeri, O’Loughlin & Bribiesca-Contreras, 2017

O’Loughlin, P. Mark & Bribiesca-Contreras, Guadalupe, 2017, New asterinid seastars from the western Pacific Ocean (Echinodermata: Asteroidea), Memoirs of Museum Victoria (Mem. Mus. Vic.) 76, pp. 121-132 : 128-131

Aquilonastra starmeri sp. nov.

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

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Figures 7 , 8 , 9a–d .

Material examined. Holotype. Palau, off NE Ngeryktabe Island , rocky islets, 7º 18.26’ N, 134º 27.25’ E, 10 m, coll. J. Starmer, 5 Mar 2003, code BPAL –081, photo GP 954 , UF 1612 (in 75% ethanol; many spinelets lost with handling over time).

Description. Asterinid seastar, five sub-equal rays, rays wide basally, bluntly rounded distally, R = 20 mm, r = 12 mm, rays merge at bases, inter-radial junction of rays with shallow incurve, central rays with high elevation and rounded abactinally, distinct broad inter-radial low non-papulate apron marginally, up to about 7 plates wide longitudinally, rays flat actinally, margin acute. Not fissiparous. No abactinal or actinal gonopores detected. No pedicellariae detected. Superomarginal plates in irregular series, slightly smaller than projecting inferomarginal plates, subequal in size with adjacent irregular apron plates. Broad low proximal marginal apron supported by internal superactinal plates, outer marginal apron supported by contiguous abactinal and actinal plates; some small superambulacral plates present. Glassy convexities on cleared abactinal and actinal plates.

Abactinal: disc discrete, small, demarcated irregularly by 5 wide doubly or singly papulate radial plates and 5 smaller inter-radial plates; single conspicuous madreporite, above junction of bases of two rays. Abactinal plates imbricate, indented proximally for single papula, rarely 2; no carinal series of plates, only one doubly papulate carinal plate; small secondary plates on disc and few abactinally; abactinal plates in about 6 longitudinal series down each side of each ray, plates with elevated rounded proximal edge, about 20 papular plates in uppermost series, 1–3 in lowest series. Surface of abactinal plates covered with up to about 40 short conical to digitiform spinelets, not sacciform, not clustered, spinelets readily lost; spinelets on abactinal apron acicular, conical, subsacciform, about 6 per plate; superomarginal plates with fewer spinelets.

Actinal: inter-radial plates in longitudinal and oblique transverse series from the ambulacrum. Actinal spines per plate: oral 11, long conical, fused basally, shorter distally; suboral about 8, long conical proximally to short distally; furrow 5, conical, fused basally; subambulacral 4, conical, fused basally; actinal 3–5, conical, fused basally; inferomarginal up to about 12, digitiform, short actinally.

Distribution. Palau, off NE Ngeryktabe Island, rocky islets, 10 m.

Etymology. Named for John Starmer who collected and documented the type specimen.

Remarks. Aquilonastra starmeri sp. nov. is distinguished from many Aquilonstra species by lacking pedicellariae, lacking carinal series of plates and having a non-fissiparous habit. Aquilonastra species that lack pedicellariae but are fissiparous are: Aquilonastra burtoni ( Gray, 1840) ; Aquilonastra cassini O’Loughlin and Bribiesca-Contreras, 2015 ; Aquilonastra chantalae O’Loughlin and Mackenzie, 2013 ; Aquilonastra colemani O’Loughlin and Rowe, 2006 ; Aquilonastra conandae O’Loughlin and Rowe, 2006 ; Aquilonastra doranae O’Loughlin and Rowe, 2006 ; Aquilonastra moosleitneri O’Loughlin and Rowe, 2006 ; Aquilonastra yairi O’Loughlin and Rowe, 2006 . Aquilonastra starmeri sp. nov has 3–5 actinal inter-radial spines per plate and is thus distinguished from those with up to eight and more: Aquilonastra byrneae O’Loughlin and Rowe, 2006 ; Aquilonastra cepheus (Müller and Troschel, 1834) ; Aquilonastra limboonkengi ( Smith, 1927) ; Aquilonastra samyni O’Loughlin and Rowe, 2006 . Aquilonastra starmeri sp. nov. has uniformly rounded rays abactinally and is distinguished from those with paxilliform rays: Aquilonastra lorioli ( Koehler, 1910) ; Aquilonastra minor ( Hayashi, 1974) ; Aquilonastra rosea (H.L. Clark, 1938) . Aquilonastra starmeri sp. nov. is distinguished from the remaining species assigned to Aquilonastra that are not fissiparous and lack prominent pedicellariae as follows: Aquilonastra alisonae O’Loughlin and Bribiesca-Contreras, 2015 has splay-pointed abactinal spinelets; Aquilonastra halseyae O’Loughlin and Rowe, 2006 has sacciform spinelets and the primary superomarginal plates are frequently separated by smaller plates; Aquilonastra marshae O’Loughlin and Rowe, 2006 has some doubly papulate carinal series of plates; Aquilonastra oharai O’Loughlin and Rowe, 2006 has spinelets in double splayed series across the proximal edge of abactinal plates; Aquilonastra scobinata ( Livingstone, 1933) has carinal series of singly papulate plates and long thin pencil-like sacciform splay-pointed spinelets. We note again that Aquilonastra corallicola was described for Palau and is fissiparous.

Figures

Figure 7. Montage photograph of the holotype of Aquilonastra starmeri sp. nov. (UF 1612). Abactinal view showing five sub-equal rays, distinct marginal apron, lacking carinal series of plates, single large madreporite. The abactinal plates have become denuded of most spinelets over time.

Figure 8. Montage photograph of the holotype of Aquilonastra starmeri sp. nov. (UF 1612). Actinal view showing five sub-equal rays, spination, longitudinal and oblique-transverse series of actinal plates.

Figure 9. Montage photographs of the holotype of Aquilonastra starmeri sp. nov. (UF 1612): a, abactinal view of disc (left) and proximal ray plates with short conical to digitiform spinelets; b, abactinal details of distal interradius showing acicular conical to subsacciform spinelets on apron, and supero- and inferomarginal plates; c, actinal view showing oral, suboral, furrow and actinal interradial spines; d, transverse section of a ray with superambulacral plate (left) and superactinal plate (right) highlighted.