Paraliparis membranaceus Guenther 1887

David L. Stein, 2005, Descriptions of four new species, redescription of Paraliparis membranaceus, and additional data on species of the fish family Liparidae (Pisces, Scorpaeniformes) from the west coast of South America and the Indian Ocean., Zootaxa 1019, pp. 1-25 : 8-10

Paraliparis membranaceus Guenther 1887

(Fig. 3)

Material Examined. Holotype. BMNH 1887.12.7.20, 65 mm TL, 57 mm SL, “Challenger” Sta. 310, 51° 27'30" S, 74° 03' W, off Cabo San Vicente, Sarmiento Channel, Chile, 10 January 1876, 738 m. Poor condition.

Description. Head short, compressed, its depth about equal to its length; dorsal profile and snout evenly rounded, mouth terminal or subterminal; eye large, 22.4 %, snout a little longer, about 26 % HL. Interorbital space much wider than eye diameter, very convex. Nostrils single, the nares immediately anterior to orbit and on a horizontal through its center; rosette oval, consisting of six pairs of laminae, immediately anterior to anterodorsal quadrant of orbit. Mouth distinctly oblique; upper jaw reaching to below rear margin of orbit, about 44 % HL. Teeth small, thorn-like canines, in about 40 oblique rows forming a narrow band four or fewer teeth wide except posteriorly, where it is uniserial for fewer than 10 rows; symphyseal gap apparently narrow. Mandibular teeth similar in character and arrangement. Suborbital stay long, slender, pointing posteroventrally at an angle of about 30°. Opercular flap short; gill opening short, entirely above pectoral fin.

Pectoral fin of about 25 rays (17+8), uppermost ray even with or slightly below rear corner of maxilla; symphysis far forward, below or in front of anterior margin of orbit. Upper lobe much longer than head, 134.3 %, lower lobe shorter, 78.3 % HL. Lower lobe rays eight, notch ray spacing apparently not distinctly wider, not clearly separated from more dorsal rays. All rays long, emarginate, providing appearance of a fringe along fin edge.

Body compressed, relatively deep, deepest point about at occiput, about equal to head length; tapering evenly to caudal from a point behind the abdominal cavity, where dorsal fin is deepest. Vertebrae more than 45. Skin folds of both dorsal and anal fins extending anteriorly. Abdominal cavity short, anus far forward between lower pectoral fin lobes, below rear or center of orbit. Dorsal fin origin above opercular flap, anal fin origin apparently far forward. Caudal fin of two to three fine, long, rays, tapering to a point.

Skin transparent, heavily dotted with small melanophores, especially on dorsal and anal fins. Muscles pale. Oral cavity paler anteriorly, more thickly dotted with melanophores posteriorly; gill cavity dark, pigment visible through membranes of branchiostegal rays. Tongue closely dotted with melanophores on its dorsal surface but not ventrally. Peritoneum dark brown, visible through body wall; stomach dark brown, pyloric caeca pale.

Remarks. Paraliparis membranaceus is similar in many important characters to P. molinai Stein et al. 1991 , collected off Chile at similar depths but farther north. These include an oblique mouth, number of pectoral fin rays (25 and 24), ventral position of the pectoral fin (dorsal ray even with or below posterior corner of maxilla, symphysis far forward below the eye), and reduced caudal fin (4 rays in P. molinai , 2-3 in P. membranaceus ). However, P. membranaceus differs significantly in some key characters: it has premaxillary teeth in short oblique rows forming a narrow band (vs. biserial), lacks a noticeable gap between the rays of the upper and lower pectoral fin lobes (vs. distinctly wider spacing of the three notch rays), the stomach is dark brown (vs. pale yellow), and the oral cavity is heavily dotted on a pale background (vs. dark brown). In the unlikely event that these differences are size-related, it could be a senior synonym of P. molinai .

This species has been recorded only once, and I could find no evidence of any subsequent reexamination in the literature. Although the actual collection information is obscure but unequivocal (Murray, 1895), Günther ’s (1887) description omitted to say it was from Chile (“... off Cape St. Vincent, Station 310 ...”). Subsequently, no one sought the actual collection data, and even the Natural History Museum on-line catalogue included incorrect collection data (subsequently corrected). Lindberg (1973) misinterpreted “Cape St. Vincent” to mean “off Portugal”, the location of the best known geographic feature of that name. Stein and Able (1986) followed Lindberg; thus Stein et al. (1991) omitted it from their review of Chilean liparids, and Andriashev (2003) did not include it in his review of Southern Ocean species. However, in the course of preparing an account of liparids of the East-Central Atlantic, when collection data for the specimen was obtained, Lindberg’s erroneous assumption became obvious; the specimen is clearly from fiord waters of southern Chile.

Günther ’s description provides relatively little information, but his figure is excellent, appears to be exceptionally precise, and is stated to be “of the natural size”. The specimen length was given as “2 1/4 inches long” (e.g., 57 mm), and the drawing total length is 65 mm (the end of the caudal peduncle is not shown), so it seems that 2 1/4 inches was the standard length and total length of the specimen was 65 mm. Thus, some measurements and the pectoral fin-ray counts used here were taken directly from the drawing. There is one apparent error in the description, which states “pectoral fin very large, with a very broad base, extending from the upper end of the gill-opening forward ...” but this is unlikely to be correct because almost all known liparids have the gill opening starting above the pectoral fin. I suggest that Günther meant “lower” rather than upper, indicating that the gill opening was short and completely above the pectoral fin.

Although at the time of its description, the holotype was clearly in excellent condition (Fig. 3A), it is now in poor condition, fragile, and will probably disintegrate in the near future (Fig. 3B, C). It is missing the caudal fin, hypural complex, the abdominal walls, most of the internal organs and skin, and has badly damaged pectoral fins and jaws. The redescription is a combination of Günther ’s description, data from his figure, and from my own examination of the specimen.