Ophiocreas oedipus Lyman, 1879

Calero, Belén & Ramil, Fran, 2023, Euryalida (Echinodermata, Ophiuroidea) from Northwest Africa, European Journal of Taxonomy 870, pp. 46-75 : 57

Ophiocreas oedipus Lyman, 1879

Figs 3D , 4C, H–I , 6

Ophiocreas oedipus – Lyman, 1879: 65, pl. XVI figs 443–446.

Ophiocreas oedipus – Lyman, 1882: 283, pl. XXXI figs 5–8, pl. XLVI fig. 1. — Koehler, 1909: 206, pl. VII fig. 2. — Clark, 1911: 283. — Paterson 1985: 18, fig. 10. — McKnight, 1993: 174.

Material examined

WESTERN SAHARA • 1 spec., 10.42 mm dd; 26°39′46″– 26°41′48″ N, 14°45′20″– 14°42′44″ W; depth 1593– 1588 m; 8 Dec. 2005; Maroc-0511 exped.; stn MO171; Maroc-0511-16715 ; LZM-UV • 1 spec., 10.88 mm dd; 26°23′25″– 26°26′32″ N, 15°17′44″– 15°18′14″ W; depth 1615–1755 m; 11 Dec. 2005; Maroc-0511 exped.; stn MO181; Maroc-051107632 ; LZM-UV.

Distribution

Ophiocreas oedipus Lyman, 1879 has a wide geographical distribution in warm and temperate waters. It has been recorded in the Indo-Pacific area ( New Zealand to Japan) ( Koehler 1904; Clark 1911; Baker 1980; McKnight 1993), between 350 (material deposited in MNHN) and 1994 m ( Koehler 1904). In the Atlantic Ocean, it was reported from Ascension Island between 756 and 778 m ( Lyman 1882), Madeira from 1500 to 1968 m ( Koehler 1909) and from several Northwest Atlantic seamounts ( Mosher & Watling 2009; Cho & Shank 2010).

We collected this species at only four stations in Western Sahara, between 909 and 1755 m depth, representing the first record on West African continental margin.

Remarks

Ophiocreas oedipus and Asteroschema inornatum are very similar species. Nevertheless, they can be distinguished chiefly by several characters. In A. inornatum , both dorsal and ventral surfaces are more densely covered by granules, even in juveniles. However, the dorsal granulation on the disc seems to be a slightly variable character in O. oedipus , with different densities of coverage among specimens. Radial shields are quite parallel and aligned with the arms in A. inornatum , giving continuity between the disc and arms; however, in O. oedipus , the radial shields are divergent – closer in the proximal part – and with a marked ridge, forming a border between the disc and arms. Finally, in O. oedipus , the tooth line (not the ventral-most teeth) is truncated, while that of A. inornatum is more pointed. Besides, we found other slight differences between the species: genital slits are smaller and triangular-shaped in A. inornatum and longer and parallel in O. oedipus . In both species, oral papillae are granule-shaped, but these papillae are bigger in A. inornatum . Moreover, in O. oedipus , the arms have well-marked ridges, mostly proximally, and the proximal segments are widened dorsally, creating a median groove along the arm. However, A. inornatum does not have a well-marked ridge, but some specimens show the medial groove along the arm. According to Paterson (1985), these grooves can be related to gonadal development. Living colour of the species is orange-pink with purple hues on the dorsal part, dark underparts, almost black. This species was found, sometimes in large numbers, living on Acanthogorgiidae gorgonians.

Figures

Fig. 3. A–B. Asteronyx loveni Müller & Troschel, 1842 collected from Mauritanian waters on Distichoptilum gracile Verrill, 1882. C. Asterochema inornatum Koehler, 1906 collected from Western Sahara waters on Paramuricea sp. Koelliker, 1865. D. Ophiocreas oedipus Lyman, 1879 collected from Western Sahara waters, on Acanthogorgiidae indet. E–F. Astrodendrum juancarlosi sp. nov. (LZM-UV Bissau-0810-06146), specimens collected from Guinea Bissau waters. Not to scale.

Fig. 4. A, D–E. Asteronyx loveni Müller & Troschel, 1842 (LZM-UV Maurit-1107-04528). A. One specimen collected over Anthoptilum murrayi Kölliker, 1880. D. Dorsal view. E. Ventral view. B, F–G. Asterochema inornatumKoehler, 1906 (LZM-UV Maroc-0511-16532). B. Dorsal view.F. Detail of dorsal disc. G. Ventral view. C, H–I. Ophiocreas oedipus Lyman, 1879 (LZM-UV Maroc-0611-07763). C. Dorsal view. H. Detail of dorsal disc. I. Ventral view.

Fig. 6. Map from the study area with the location of the stations where specimens of Ophiocreas oedipus Lyman, 1879 were collected during the ten surveys off Northwest Africa.