Author: (Capello, 1867)
Hydrolagus affinis (Capello, 1867)
Status in World Register of Marine Species:
Accepted name: Hydrolagus affinis (de Brito Capello, 1868) (updated 2009-06-25)
Diagnosis: body greatly tapering from a massive head and trunk to a pointed caudal fin with a short filament at its tip. Snout short, somewhat conical, overhanging mouth. First dorsal fin short-based, triangular and high, with a strong spine in front (joined nearly its whole length to the fin); second dorsal fin long, continuous to upper caudal fin, not more than one-third height of first, of even height throughout; pectoral fins not reaching to pelvic fin base when laid back; anal fin continuous with lanceolate caudal fin, the latter with lower lobe continued forward as a low fleshy ridge. Skin smooth except for denticles on male organs. Colour: uniform dark violet/brown, fins somewhat paler but with dark edges. Size: to about 130 cm TL.
Habitat: benthopelagic on continental slopes and down to deep-sea plains from 300 m (rare) to 2,400 m or more, mainly in very deep water; moderately rare. Behaviour: more or less stationary as indicated by a few deepsea observations. Food: small fishes and invertebrates. Reproduction: neither egg capsules nor juveniles known.
Distribution: Atlantic coasts off Portugal, northern Bay of Biscay and Rockall Trough. Elsewhere, western Atlantic from off Newfoundland to latitude of Cape Cod. Probably a much wider distribution than the records show.
Note: German deep trawls in the Rockall Trough have produced, together with H. affinis, several large Hydrolagus of a uniform light grey to white, possibly representing a third species in this area (Stehmann, unpublished data).
Eggs, embryonic and young stages. Dean, 1906: 111, fig. 90 (late embryo).