Bathyraja Ishiyama, 1958

Knuckey, James D. S. & Ebert, David A., 2022, A taxonomic revision of Northeast Pacific softnose skates (Rajiformes: Arhynchobatidae: Bathyraja Ishiyama), Zootaxa 5142 (1), pp. 1-89 : 6

Bathyraja Ishiyama, 1958

Softnose skates

Bathyraja (subgenus of Breviraja ) Ishiyama (1958): 325 [133].

Type species. Raja isotrachys Günther (1877) , by original description.

Diagnosis. Small to very large skates, disc rhomboidal-shaped, rather broad, width usually greater than disc length, pectoral fin corners angular to broadly rounded at tips. Snout flabby, flexible, and soft; rostral cartilages relatively slender, uncalcified, possessing small anterior notches that lie on either side of short, anterior, free projections of the axis; small appendices of the cartilage that are broadly united with the subterminal part of the elongated axis, with each appendix extending backwards a short distance as a slender, unnotched process paralleling the axis; and the posterior wing of each appendix separated from the axial rod by a notch about half as long as the whole appendix. Mouth small to relatively wide, slightly arched; teeth with single large cusp, angled rearward, and arranged in quincunx; tooth row counts upper and lower jaws 21–42. Tail relatively short, its length equal to or less than disc width. Dorsal fins usually two, subequal, similar in shape. Skin smooth or roughly textured by dermal denticles on dorsal and ventral surfaces. Dermal denticles present or absent on dorsal surface of disc and tail, but rarely present on ventral surface of disc and tail. Thorns on dorsal surface, if present, usually on nuchal, scapular, and midback areas; predorsal tail thorns mostly in single row; interdorsal thorns present or absent; ventral surface usually without thorns; mature males possess alar thorns, malar thorns absent. Claspers lack a large, thin, flake-like shield, the small ventral terminal that is hidden within the skin of the ventral lobe, and possess a pseudorhipidion and often a pseudosiphon. Vertebral counts: trunk 31–39, predorsal 68–122. Spiral valve counts 8–15. Maximum total length ranges from about 60 cm to over 200 cm. Coloration varies from whitish to dark brown, purplish, or black; dorsal surface either plain or with blotches or spots; ventral surface usually white, depending on the species may have dark blotches between gills or on abdomen, or gray edging on disc and pelvic fins.

Distribution and Habitat. Softnose skates are most common at higher latitudes and in deeper waters, and inhabit continental and insular shelves from 17–3,322 m deep ( Ebert & Winton, 2010; Last et al., 2016; Kuhnz et al., 2019). Temperature preferences observed to be very cold to moderate, ranging from 1.6–13.2°C ( Kuhnz et al., 2019). The genus can tolerate a fairly wide range of oxygen levels, with reported ranges from 0.1–3.5ml l-1 ( Kuhnz et al., 2019).

Etymology. The generic name derives from the Greek bathos, meaning deep, and raja, meaning skate, which is a reference to the depth range. The common name softnose skates refer to the short, flexible snout.