Author: (Lowe, 1839)
Two spined dorsal fins, no anal fin, bladelike unicuspidate teeth in lower jaw and teeth with cusps and cusplets in upper jaw, relatively short snout, low, truncated denticles.
A fairly slender-bodied lanternshark with a moderately short tail, distance from pelvic insertions to ventral caudal origin somewhat greater or less than tip of snout to first gill openings, between 1.5 to 2 times in distance between pectoral and pelvic bases, and about 1.5 in interdorsal space; distance between pectoral and pelvic bases moderately long in adults, about 1.3 times head length; distance from snout tip to first dorsal spine about equal to distance from first dorsal spine to second dorsal insertion. Head width about equal to preoral snout; prespiracular length slightly greater than distance from spiracles to pectoral origins; gill openings rather long, much wider than spiracle, 1/2 eye length or less; upper teeth generally with less than 3 pairs of cusplets. Origin of first dorsal fin about opposite or slightly behind free rear tips of pectoral fins, dorsal fin base much closer to pectoral bases than pelvics; interdorsal space fairly long, nearly or quite as long as distance from snout tip to pectoral insertions; second dorsal fin much larger than first, but with area less than twice that of first; distance between second dorsal base and upper caudal origin between 2 and 3 in interdorsal space; caudal fin moderately short and broad, length of dorsal caudal margin slightly less than head length. Lateral trunk denticles with truncated, hollow, sessile, low crowns, not thorn or bristle-like, wide-spaced but not arranged in regular longitudinal rows; snout covered with denticles; no rows of greatly enlarged denticles on flanks above pectoral fins. Distal margins of fins largely covered with skin, not fringed with naked ceratotrichia. Colour blackish-brown above, with an obscure broad black mark running above, in front and behind pelvic fins.
Western Atlantic: Northern Gulf of Mexico and southern Brazil to Argentina. Central South Atlantic (oceanic), between Argentina and South Africa. Eastern Atlantic: Portugal, Madeira, Azores, Canaries, Liberia, Ivory Coast to Gabon, Zaire, Angola and Namibia. Western Indian Ocean: South Africa. Western Pacific: Japan (southeastern Honshu).
Habitat and Biology:
A lanternshark of the continental slopes, on or near bottom at a depth of 274 to 1000 m or more (possibly to 1998 m); also oceanic in the central South Atlantic, at depths between the surface and 110 to 708 m over deepwater (Krefft, 1980). Ovoviviparous. Eats fish eggs, lanternfishes, squids and other small dogfishes.
Size: Maximum total length at least 47 cm, possibly to between 50 and 100 cm; adult males 31 to 39 cm, females 38 to 47 cm.
Interest to Fisheries:
In the eastern Atlantic captured in bottom trawls and in fixed bottom nets, also with line gear, and utilized dried salted for human consumption and for fishmeal.
I follow Krefft (1968), who examined one of the syntypes of E. frontimaculatus, in placing that species in Oynonymy of E. pusillus. Nakaya (1982) reported an Etmopterus from the Kyushu-Palau Ridge in 340to 370 m depth with pusillus-like denticles but with a far longer snout and more anterior first dorsal fin. This is probably a new species.
Holotype: British Museum (Natural History). Type Locality: Madeira, eastern Atlantic.