Asteronyx luzonicus Döderlein, 1927

Baker, Alan N., Okanishi, Masanori & Pawson, David L., 2018, Euryalid brittle stars from the International Indian Ocean Expedition 1963 - 64 (Echinodermata: Ophiuroidea: Euryalida), Zootaxa 4392 (1), pp. 1-27 : 7-8

Asteronyx luzonicus Döderlein, 1927

( Figs. 4F–G , 5A–C )

Asteronyx luzonicus Döderlein, 1927: 64 , pl. 7 figs. 4–6d.

Material Examined. USNM 1072474 , Anton Bruun Cruise 1 Station 17, southern Andaman Sea, 7° 38’ N 97° 09’ E, 280– 275 m, 21 March 1963, 1 specimen ; Anton Bruun Cruise 7 Station 369F, off southern Mozambique, 24° 07’S, 36° 11’–15’E, 1600–1628 m, 17 August 1964, 1 specimen .

Remarks. The disc diameters of the two specimens are 15 mm ( Fig. 4F–G ) and 6 mm respectively. The larger specimen has narrow arms approximately 140 mm long ( Fig. 4F–G ). The larger specimen has a naked skin-covered disc with dark spots aborally and orally ( Fig. 5A–B ), and with some light calcification between one pair of radial shields ( Fig. 5A ). The genital slit is narrow, situated between arm segments 1 and 3, and is not in a pouch ( Fig. 5B ), as in the type species, A. loveni . At arm segment 22, the lowermost arm spine is elongate, with a terminal club ( Fig. 5C ). This elongate arm spine is not present on the smaller specimen, and may therefore be ontogenetic as is the number of arm spines. A similar enlargement of mid-arm spines has been noted in A. loveni ( Baker 1980) . The dark spots on their disc is a main diagnostic character of A. luzonicus ( Döderlein, 1927) .

This species has remarkable bathymetric distribution, between 109 and 2963 m. A. luzonicus was originally described from the Philippines; its occurrence in the southern Andaman Sea and the Mozambique Channel represents a considerable extension of its geographic range, but one that might be expected given its bathymetric range.

Figures

FIGURE 4. Trichaster flagellifer (USNM 1072573) (A–E) and Asteronyx luzonicus (USNM 1072474) (F–G). A, aboral view; B, oral view; C, aboral central view; D, aboral peripheral view; E, oral basal portion of the arm; F, aboral view; G, oral view.

FIGURE 5. Asteronyx luzonicus (USNM 1072474) (A–C) and Astroboa clavata (USNM 1072477) (D–J). A, aboral disc; B, lateral disc; C, basal portion of the arm; arrows indicate elongated club-shaped arm spines; D, aboral view; E, oral view; F, aboral peripheral disc; G, external ossicles on a peripheral radial shield; H, oral basal portion of the arm; I, aboral middle portion of the arm; J, aboral distal portion of the arm.