A new species and a review of the deep-sea fish genus Porogadus (Ophidiidae) from the western North Atlantic

A new species of deep-sea ophidiid, Porogadus situs, is described from deep water off the Bahamas, It differs from its congeners chiefly in having a relatively shorter and deeper head, absence of preopercular and frontal spines and relatively large scales covering the body. A partial osteological description of P. situs is given. porogadus is reviewed and a provisional key to species from the western North Atlantic is presented. The species group containing Porogadus that lack well developed head spines and armature is partially revised on the basis of a study of specimens collected from the Atlantic and Pacific oceans. Of the seven nominal species of Porogadus with poorly developed head spines, five are recognized: P. catena (with P. promelas and P. breviceps as synonyms), P. abyssalis, P. gracilis, P. longiceps and P. situs n. sp. The circum global neobythitine ophidiid genus Porogadus includes long and slender benthopelagic fishes inhabiting bathyal and abyssal depths beneath tropical and temperate seas. The 14 nominal species referred to Porogadus are much in need of revision (Cohen and Nielsen, 1978). Porogadus is presently distinguished from other neobythitine genera by a combination of the following characters (Cohen and Nielsen, 1978): presence ofa single median basibranchial tooth patch, V-shaped vomerine tooth patch, 13 to 20 developed rakers on first arch, six caudal fin rays, 17-20 pectoral fin rays, one or two rays in each pelvic fin, eight branchiostegal rays, 16-18 precaudal vertebrae, a row of modified scales dorsally behind the head, a body depth (at vent) that goes into its standard length 10 or more times, prominent cephalic lateralis pores beneath eye and along posterior margin of preopercle, body lateral line arranged in three parallel rows (pores large and prominent in some species). The generic diagnosis given above appears to best accommodate Porogadus species with strongly developed head spines, typified by Porogadus miles. Members of the genus with poorly developed head spines are highly variable or wanting in several characters presently used to define the genus. For example, in the new species described herein, there is no median basibranchial tooth patch in more than half the specimens examined; the vomerine tooth patch is occasionally irregular in shape; and three lateral line rows are not evident. Such deviations from the generic diagnosis were also observed in other species of Porogadus with poorly developed head armature. We urge caution in discussing relationships until there is a better understanding of generic characters. Unfortunately, taxonomically important species of Porogadus described from the Indian and western Pacific oceans are still quite rare in collections and a world-wide revision is not now possible. The genus Porogadus was established by Goode and Bean (1886) for Porogadus miles, based on a single specimen collected in the Atlantic Ocean off the east coast of North America; thirteen additional species have been described. Norman's (1939) synopsis of oceanic genera, with a list of described species, represented an early attempt to arrange "brotulid" genera in accordance with their supposed relationships and was based in part on the prior work of Smith and Radcliffe (1913). Nybelin (1957) reviewed the genus Porogadus and provided comments