Deto aucklandiae (Thomson, 1879)
A marine (seashore) species. Found on New Zealand subantarctic islands (Auckland and Campbell Islands, Snares Island), on the seashore about the high-water mark, and in and around rock pools (Chilton, 1909; Chilton, 1915).
A large, robust species. Sexually dimorphic. Males with very large, thick, hyper-developed antennae, dorsal surface with transverse rows of tubercles which on the pereon are elongated to form blunt spines, male body length 20-24 mm. Females with more slender antennae, body length 12-19 mm, dorsal surface with transverse rows of tubercles. In females the epimera of segments 2,3 and 4 of the pereon are separated from the rest of the segment by a slight groove (see 'Female lateral' photo); in males this groove is absent.
Flagellum of antennae with 4 articles, the 4th (distal) segment is very small. Head with lateral processes forming broad lobes. Eyes relatively small in size, bean-shaped, and composed of multiple ocelli. Uropods with both rami visible, rami approximately equal in size and shape, endopods close together and parallel.
Can be confused with Deto bucculenta (Stewart Island, Chatham Islands), in which males have the lateral portions of the first segment of the pereon dilated into two bladder-like structures, and with Scyphoniscus magnus, which differs in the shape of the uropods.
Juveniles can be difficult to identify.