Deep-Water Crustacea of the Genus Sergestes (Decapoda, Natantia) from Cook Strait, New Zealand
A relatively small, fragile shrimp with long appendages and characteristically prominent laterally-directed eye stalks.
Rostrum short, acute, projecting slightly beyond the anterior margin of the carapace and with the dorsal margin weakly convex. Supraorbital crest armed with spine; cervical groove distinct, terminating near the prominent hepatic spine. Suprabranchial groove and ridge well marked.
Eyes large, black, cornea wider than stalk, no protuberance (ocular tubercle) on the latter. Antennular peduncular segments long and relatively slender, second and third together subequal to proximal, third a little longer than second. Third maxillipeds not greatly enlarged, subequal in length to 3rd pereiopods. Only one margin of the two distal segments of the 5th pereiopods fringed with setae.
Figs. 1–5. Sergestes arcticus.—Fig. 1, carapace, lateral view (anterior organ of Pesta represented by broken circle) ♀. Fig. 2—Anterior part cephalothorax, lateral view (setae omitted) ♀ 10 mm. Fig. 3—immature left petasma, posterior view, ♂ 8 mm. Fig. 4—Right petasma. posterior view, ♂ carapace length 12 mm. Fig. 5—As preceding, anterior view.
Figs. 6–9. Sergestes japonicus.—Fig. 6—Carapace, lateral view, ♀ Fig. 7—Anterior part cephalothorax, lateral view (setae omitted), ♀ 28 mm. Fig. 8—Left petasma, posterior view, ♂ 21 mm. Fig. 9—As preceding, anterior view.
Female with two curved teeth medially on coxa of 3rd pereiopod.
Carapace length of New Zealand specimens up to 15 mm, males tend to be smaller than females.