Ophiacantha costata Lütken & Mortensen, 1899

Fig. 8A‒F

Ophiacantha costata Lütken & Mortensen, 1899: 172‒173, pl. 16, fig. 10, pl. 17, figs. 4‒6.

Material examined. Two individuals at two stations. TALUD VIII, Sta. 11, 1 ind. (ICML-EMU-11695); TALUD XII, Sta. 28, 1 ind. (ICML-EMU-11700).

Comparative material. Syntypes, 9 ind.: MCZ OPH-1941, MNHN 2013-10259, USNM 19573, USNM 19574 (Supplementary file 2).

Description (ICML-EMU-11700). DD = 6 mm. Disc interadii deeply indented. Dorsal disc covered by scales and short multifid spines. Primary plates not evident. RS slender, elongated, covered by multifid spines (Fig. 8A). Ventral interradii very reduced, covered by imbricated scales and spines similar to those on the dorsal side (Fig. 8B). OSh broader than long, diamond-shape with distal rounded edge. Madreporite swollen. AdSh longer than broad, semilunar; almost meeting or meeting in front of OSh. Jaws bearing five papillae at each side; AdShSp lanceolate; LOPa three, lanceolate, first the longest of all oral papillae, the rest slender; IPa pointed. vT longer than oral papillae (Fig. 8C). Arms slender, gradually narrowing distally. First DAP reduced, covered by short multifid spines; subsequent DAP slightly longer than broad, bell-shaped with rounded edges; separated from each other by lateral plates (Fig. 8D). VAP broader than long, pentagonal, separated from each other. LAP with six ArSp, large (approximately 1.5 arm segment in length), serrated, dorsalmost the longest and ventralmost the shortest. One elongated, pointed TSc (Fig. 8E). Color pattern beige (ethanol preservation) (Fig. 8A‒F).

Habitat and distribution. California, USA, Mexico, and Panama; 733‒ 1,271 m depth, sandy substrates (Lütken & Mortensen 1899; Maluf 1988). The material examined was collected in the southern Gulf of California and off Colima; 920‒ 1,106 m depth.

Remarks. The widely open genital slits (Fig. 8B) in our examined material can be an artifact of preservation or a stress reaction to the fixing process (pers. comm. Sabine Stöhr, 2022). Previously recorded in the Gulf of California and off Marias Islands (Granja-Fernández et al. 2015). The examined material collected off Colima corresponds to a new distribution record for this area and the southernmost record in the Mexican Pacific.