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Author: Hulley and Penrith, 1966

Field Marks:
Conical, moderately long, blunt, compressed snout, compressed body, no dorsal fin spines, cloacal gland, lobate, chimaera-like pectoral fins, no anal fin, gill slits increasing greatly in size from front to back, midventral keel on caudal peduncle, asymmetrical caudal fin, needle-like upper teeth and bladelike lowers, dark colour with conspicuous light fin margins.

Diagnostic Features:
Anterior nasal flaps very short, not expanded into barbels; snout moderately long, compressed and conical, length about 2/5 of head length and less than distance from mouth to pectoral origins; gill openings increasing in size from front to back, 5th over twice length of first; lips thick, fringed, but not suctorial; teeth strongly different in upper and lower jaws, uppers small, with narrow, acute, erect cusps and no cusplets, not bladelike, lowers much larger, bladelike, interlocked, with a high, broad, nearly erect cusp and distal blade, edges not serrated; tooth rows 29/34. Both dorsal fins spineless; first dorsal origin well behind free rear tips of pectoral fins, insertion about equidistant between pectoral and pelvic bases and well ahead of pelvic origins; second dorsal fin somewhat larger than first, base less than 1.5 times length of first dorsal base; origin of second dorsal well ahead of pelvic origins; pectoral fins with greatly expanded, broadly lobate free rear tips and inner margins, much as in chimaeras; caudal fin asymmetrical, not paddle-shaped, upper lobe long, lower lobe moderately long subterminal notch well-developed. No precaudal pits or lateral keels on caudal peduncle, but with a midventral keel. Dermal denticles flat and blocklike, not pedicellate, no posterior cusps on flat, depressed crowns. Cloaca greatly expanded and modified as a luminous gland with secretory papillae. Colour blackish brown with conspicuous light fin margins.

Geographical Distribution:
South Atlantic: West of Cape Town, South Africa and east of Uruguay.

Habitat and Biology:
A little-known, extraordinarily specialized, oceanic dwarf shark, known only from two specimens. One was caught near short in a bottom trawl (holotype), buta second specimen was captured near the surface (0 to 25 m deep) far offshore (Krefft, 1980). Mode of reproduction unknown, probably ovoviviparous with few young. The cloaca of this shark is greatly expanded into a gland with internal villi that secret a blue luminous substance (M. Stehmann, pers.comm.); this will be reported in detail elsewhere. The broadly lobate, muscularbased pectoral fins, situated on the compressed body in a position similar to the pectoral fins of chimaeras, suggest that pectoral propulsion or at least pectoral hovering is important in this shark. Food unknown; the powerful jaws and sharp lower teeth suggest that this species can take relatively large prey.

Size:
An adult male was 41.6 cm long; the 17.6 cm holotype was originally recorded as an adult male, but turned out to be an immature female.

Interest to Fisheries: None.

Type material:
Holotype: South African Museum, SAM 23577,176 mm immature female. Type Locality: West of Cape Town, South Africa, 457 to 640 m depth.

Taillight shark (Euprotomicroides zantedeschia)