Ophiolimna bairdi

Ophiolimna bairdi (Lyman, 1883)

Fig. 11A‒F

Ophiacantha bairdi Lyman, 1883: 256, pl. 5, figs. 70‒72.

Ophiolimna bairdi. Lütken & Mortensen 1899: 177, pl. 18, figs. 9‒13.— H.L. Clark 1911: 230‒231.— Kyte 1969a: 1738.— Paterson 1985: 60, fig. 24.— Martynov 2010: 68, figs. 13g, 28c, 44a, 81a‒b, 82a, 82d, 82g, 82j.— Martynov & Litvinova 2008: 100‒101, fig. 17a.— Lambert & Boutillier 2011: 44, fig. 30.— O’Hara & Thuy 2022: 28, fig. 6g ‒h.

See Paterson (1985) and O’Hara & Thuy (2022) for other synonymous records.

Material examined. 95 individuals at seven stations. TALUD VIII, Sta. 3, 11 ind. (ICML-EMU-11209); Sta. 11, 5 ind. (ICML-EMU-11210-B); Sta. 15, 10 ind. (ICML-EMU-11210-A); Sta. 22, 26 ind. (ICML-EMU-11211). TALUD XII, Sta. 26, 1 ind. (ICML-EMU-11212-B); Sta. 27, 16 ind. (ICML-EMU-11212-A). TALUD XIII, Sta. 37, 26 ind. (ICML-EMU-11213).

Comparative material. Ophiacantha bairdi Lyman, 1883, holotype: MCZ OPH-1916. Paratypes, 2 ind.: MCZ OPH-1917, MNHN-IE-2013-10324 (Supplementary file 2).

Description (ICML-EMU-11211). DD = 10.8 mm. Disc pentagonal, flat. Dorsal disc covered by elongated granules and few scattered elongated spines. Primary plates and RS covered by granules (Fig. 11A). Ventral interradii covered by granules similar to dorsal granules (Fig. 11B). OSh broader than long, triangular with rounded edges. Madreporite with a rounded depression. AdSh longer than broad, slender, triangular, separated from each other. Oral plate conspicuous, covered by granules projected to OSh and AdSh. Jaws bearing five papillae at each side; AdShSp rounded; LOPa three, first LOPa oval, the rest elongated, pointed; IPa very pointed, large. vT similar in appearance to IPa but shorter (Fig. 11C). Arms fragile. First DAP covered by granules; subsequent DAP slightly longer than broad, triangular with rounded edges, slightly separated from each other (Fig. 11D). VAP slightly longer than broad, pentagonal, meeting. VAP and LAP with conspicuous horizontal striations, respectively. LAP with 7‒8 ArSp, large (approximately three arm segments in length), smooth, pointed. Tentacle pores with one lanceolate TSc (Fig. 11E). Color pattern in dorsal and ventral disc and arms brown (ethanol preservation) (Fig. 11A‒F).

Habitat and distribution. Widely distributed in the Atlantic and Pacific Oceans (Lambert & Boutillier 2011). In the Pacific it has been reported from Japan, the Okhotsk Sea, Alaska, USA, Mexico, Costa Rica, and Panama (Lütken & Mortensen 1899; H.L. Clark 1911; Lambert & Boutillier 2011; Granja-Fernández et al. 2015); 620‒ 2,600 m depth (Martynov 2010), muddy substrates (Lütken & Mortensen 1899). The material examined was collected in the southern Gulf of California and off Colima; 920‒ 2,200 m depth.

Remarks. In the material examined, even smaller specimens (DD = 5 mm) presented the characteristic horizontal striations in the ventral and lateral arm plates but with a tuberculous appearance. Moreover, these small specimens had denser spines on the dorsal disc than larger specimens. Due to its wide geographic distribution, a thorough morphological and molecular approach is needed to elucidate whether it may be a cryptic species complex. In Mexico, Ophiolimna bairdi had previously been documented off western Baja California Sur and in the Gulf of California (Granja-Fernández et al. 2015); its presence off Colima represents a new distribution record for Mexico.