Ophiacantha pacifica Lütken & Mortensen, 1899

Granja-Fernández, Rebeca, Hendrickx, Michel E., Rangel-Solís, Pedro Diego & López-Pérez, Andrés, 2023, Deep-sea Ophiuroidea (Echinodermata) collected during the TALUD cruises in western Mexico, Zootaxa 5259 (1), pp. 1-71 : 37-39

Ophiacantha pacifica Lütken & Mortensen, 1899

Fig. 10A‒F

Ophiacantha pacifica Lütken & Mortensen, 1899: 166‒167 , pl. 15, figs. 4‒6, pl. 16, fig. 11.— Stöhr & O’Hara 2021: 520‒523 , fig. 4a‒d.

Material examined. 622 individuals at seven stations. TALUD VIII, Sta. 11, 9 ind. (ICML-EMU-11193-A); Sta. 22, 28 ind. (ICML-EMU-11193-B). TALUD IX, Sta. 14, 3 ind. (ICML-EMU-11192-A); Sta. 15, 1 ind. (ICML-EMU-11192-B); Sta. 22, 8 ind. (ICML-EMU-9013-A) and 1 ind. (ICML-EMU-9013-B). TALUD XII, Sta. 27, 6 ind. (ICML-EMU-11194). TALUD XIII, Sta. 37, 561 ind. (ICML-EMU-11195) and 5 ind. (ICML-EMU-11675).

Comparative material. Syntypes, 28 ind.: MCZ OPH-1972 , MCZ OPH-2199 , USNM 19559 (Supplementary file 2) .

Description (ICML-EMU-11195). DD = 7 mm. Disc pentagonal, flat. Dorsal disc densely covered by slender multifid spines. Primary plates not evident. RS longer than broad, slender, covered by scales and multifid spines, very conspicuous distally ( Fig. 10A ). Ventral interradii covered by scales and spines similar to those on the dorsal side ( Fig. 10B ). OSh broader than long, diamond-shape. Madreporite larger than OSh. AdSh longer than broad, larger than oral OSh, almost meeting or meeting in front of OSh. Jaws bearing 3‒4 erected, lanceolate papillae at each side; AdShSp pointed; LOPa 1‒2 similar in shape to AdShSp; IPa lanceolate, pointed. vT shortest than oral papillae ( Fig. 10C ). Arms slender. DAP almost as long as broad, triangular with rounded edges, separated from each other ( Fig. 10D ). VAP broader than long, pentagonal with rounded edges, separated from each other. LAP with five ArSp, large (almost one arm segment in length), slender, smooth, blunt, dorsalmost much largest. One pointed TSc, shorter than VAP, size diminishes distally ( Fig. 10E ). Color pattern brown dorsally and beige ventrally (ethanol preservation) ( Fig. 10A‒F ).

Habitat and distribution. Southern California, USA, Mexico, and Ecuador; 362‒ 2,877 m depth, muddy and sandy substrates ( Maluf 1988; Hendrickx 2012a; See Remarks).The material examined was collected in the southern Gulf of California; 920‒ 2,309 m depth.

Remarks. According to the examination of the type material and the TALUD samples, specimens of Ophiacantha pacifica present: 1) pentagonal or rounded disc, 2) radial shields partially covered by multifid spines or naked, and 3) larger individuals (DD> 10 mm) with four oral papillae at each side of a jaw as well as up to six arm spines. Additional variations were observed by Stöhr & O’Hara (2021), who suggested that O. pacifica belongs to a species complex conformed by Ophiacantha bathybia H.L. Clark, 1911 , Ophiacantha cosmica Lyman, 1878 , and Ophiacantha sociabilis Koehler, 1897 . Ophiacantha pacifica was tentatively recorded in Mexico by Hendrickx (2012a) and Granja-Fernández et al. (2015); its presence in Mexican waters is hereby confirmed (Gulf of California).

Figures

FIGURE 10. Ophiacantha pacifica Lütken & Mortensen, 1899 (ICML-EMU-11195, DD = 7 mm). A, Dorsal disc; B, Ventral disc; C, Mouth; D, Dorsal arm; E, Ventral arm; F, Dorsal view. Ophiacantha quadrispina H.L. Clark, 1917 (ICML-EMU-12997, DD = 9.9 mm). G, Dorsal disc; H, Ventral disc; I, Mouth; J, Dorsal arm; K, Ventral arm; L, Dorsal view.