Halityle regularis 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 : 258-259

Halityle regularis Fisher, 1913

[New Japanese name: Ruriiro-mozaiku-hitode]

( Fig. 4 )

Halityle regularis Fisher, 1913: 211 ; 1919: 362. — Döderlein 1935: 108. — A.M. Clark & Rowe 1971: 53. — Baker & Marsh 1976: 107. — Jangoux 1986: 124. — A.M. Clark 1993: 304. — Rowe & Gates, 1995: 102.

Culcitaster anamesus H.L. Clark, 1914: 144 .

Halityle anamesus . — H.L. Clark, 1946: 109.

Material examined. Two specimens, RUMF-ZE-00035 (larger specimen), RUMF-ZE-00036, KUMEJIMA 2009 Stn. Trawl-77, 26° 15.606 –15.929 ʹN, 126° 49.404 –49.985 ʹE, 91–105 m, 20 November 2009.

Description. Two large specimens with R = 124.9 mm, r = 90.3 mm (R/r = 1.4), and R = 98.3 mm, r = 72.3 mm (R/r = 1.4). External features of larger specimen described below.

Abactinal side inflated ( Fig. 4A ). Abactinal plates covered with fine granule. Conspicuous, triangular papular areas among abactinal plates. Elliptical madreporite with radiating striae situated at approximately one-third r from center of disk. Longest diameter of madreporite 6 mm.

Vertical lateral side of body formed by marginal plates. Total numbers of superomarginal and inferomarginal plates 20–22 and 40–44, respectively.

Actinal surface composed of regularly arranged actinal plates. Inner plates forming 3 longitudinal series along ambulacral furrow. Rhombic or triangular odd plate placed at proximal part of each series; other plates rectangular in shape. Series of plates adjacent to adambulacral plates extending to near arm tip. Outside these 3 longitudinal series, regularly arranged smaller plates forming 5 longitudinal series; these outer series composed of elliptical or roundish square plates without odd plates. Surface of actinal plate flat, relatively smooth. Eight to 9 actinal plates of each interradial area around mouth, surrounded by relatively large, coarse granules ( Fig. 4C ).

Adambulacral plate armed with 9–11 long, flat furrow spines. Just behind furrow spines, 3–4 large, domed subambulacral spines covered with coarse granules. These subambulacral spines in very close contact with each other, forming massive bumped shape. Between adambulacral plates, 1–2 large, lanceolate pedicellariae ( Fig. 4D ).

Distribution. The type locality is the Sulu Archipelago in the southwestern Philippines at depth of 16 m. This species has also been collected from throughout the Indo-West and South Pacific region, including New Caledonia ( Jangoux 1986), the Philippines, Western Australia, Somalia, Madagascar, and Kenya ( Baker & Marsh 1976). The present study represents the first record of the species from Japan. The distribution range of the species is extended to north.

Remarks. Halityle Fisher, 1913 , is a monotypic genus. Hubert Lyman Clark (1946) transferred Culcitaster anamesus H. L. Clark, 1914 , to Halityle , but it is regarded as a junior synonym of H. regularis ( Baker & Marsh 1976; A.M. Clark 1993; Döderlein 1935).

The general appearance of the abactinal surface of this species bears some resemblance to that of Culcita novaeguineae Müller & Troschel, 1842 , which is abundant in the coral reefs of the Ryukyu Islands. Halityle regularis can be distinguished from C. novaeguineae by the regularly arranged actinal plates, and the unique colouration. The actinal plates of H. regularis are smooth and conspicuously tessellated, whereas those of C. novaeguineae are obscure and covered by numerous granules. The base colour of the abactinal and actinal surfaces of H. regularis is dark or light brown. In contrast to this inconspicuous base colour, the ambulacral furrows, and plates around the mouth are vividly coloured. The colouration of the adambulacral plates, mouth plates, and tube feet are bright yellow. The most striking colour is observed around the mouth: 8–9 actinal plates around the mouth plates of each interradial area are coloured cobalt blue with a bright yellow fringe ( Fig. 4B ).

Figures

FIGURE 4. Halityle regularis Fisher, 1913 (RUMF-ZE-00035): A, abactinal view of entire animal in living condition; B, actinal view of entire animal in living condition; C, close-up of the proximal odd plate on the actinal surface showing the smooth surface, and coarse granules surrounding the plate; D, adambulacral armature on the 14th–13th adambulacral plates with arrows indicating the lanceolate pedicellariae (proximal region is on the right). Scales: A, B = 50 mm; C, D = 2 mm.