Patagiaster sphaerioplax Fisher, 1913

Kogure, Yoichi & Fujita, Yoshihisa, 2012, A new species of Neoferdina and three new records of sea stars (Echinodermata: Asteroidea) collected from Kumejima Island, southwestern Japan *, Zootaxa 3367 (1), pp. 252-260 : 253-254

Patagiaster sphaerioplax Fisher, 1913

[New Japanese name: Nanyo-momiji]

( Fig. 1 )

Patagiaster sphaerioplax Fisher, 1913: 623 ; 1919: 154. — Jangoux et al. 1989: 168. — A.M. Clark 1989: 284.

Material examined. One specimen, RUMF-ZE-00032, KUMEJIMA 2009 Stn. Dredge-23, 26° 16.380 –15.982 ʹN, 126° 51.304 –51.502 ʹE, 125–147 m, 12 November 2009.

Description. Single specimen with R = 23.8 mm and r = 9.6 mm (R/r = 2.5). Abactinal surface covered with closely packed paxillae. Larger paxillae reaching more than 1 mm in diameter, with approximately 40 peripheral and 35 central spinelets.

Number of superomarginal plates, 16; inferomarginal plates, 16. Superomarginal plates separated from inferomarginal plates by well-developed longitudinal fasciolar groove. Superomarginal plates covered with beadlike granules and a peripheral series of slender spinelets.

All inferomarginal plates aligned opposite to superomarginal plates. Surface of inferomarginal plates completely covered with slender spinelets.

Actinal plate elliptical in shape, with slender spinelets. Single series of plates extending to 4th inferomarginal plate. Paired actinal plates located just behind mouth plates, followed by longitudinal series of 5 odd plates ( Fig. 1B ); distal margin of outermost odd plate adjoining interradial suture between 1st inferomarginal plates.

Each adambulacral plate with 7 relatively long, furrow spines, followed by 10–16 subambulacral spines arranged in more or less 3–4 longitudinal series.

Madreporite completely concealed by spinelets.

Distribution. This species was known from the vicinity of Romblon Island of the Philippine Islands at depth of 143 m (type locality), and the Flores Sea, Indonesia at depths of 350–500 m ( Jangoux et al. 1989). The present study represents the first record of the species from Japan. The distribution range of the species is extended to north.

Remarks. The material collected mostly agrees with the original description of the species. We could not confirm whether the shape of 1–3 small spines on the inferomarginal plates of the examined specimen was lanceolate or not, probably because they were abraded and damaged during the dredging operations.

The present study shows the colour in life of the abactinal surface as bright orange with the radial abactinal plates tinged with olive green ( Fig. 1A ). Prior accounts have not reported the colour in life of this rarely encountered species.

Figures

FIGURE 1. Patagiaster sphaerioplax Fisher, 1913 (RUMF-ZE-00032): A, abactinal view of entire animal in living condition; B, denuded actinal surface showing the 5 odd plates on the interradial midline. Scales: A = 10 mm; B = 2 mm.