Crustacea, the Higher Taxa

J.K. Lowry

Asellota (Isopoda, Peracarida, Malacostraca)

Description. Head. Rostrum absent; eyes sessile or stalked or absent; compound, visual elements present; ocular scale absent; naupliar eyes absent. Antennules (antenna 1) uniramous; peduncle and flagellum distinct; exopod well developed, whip-like; statocyst absent. Antennae (antenna 2) uniramous; exopod multiarticulate. Mandible uniramous; palp present. Maxillipeds, 1 pair; uniramous. Thorax. Carapace absent. Thorax and abdomen differentiated. Peraeopods (legs) 7 pairs, or 6 pairs; uniramous; non-phyllopodous; differentiated (some prehensile); coxae not forming lateral plates, or some coxae forming lateral plates. Peraeopod 1 (leg 1) simple, or subchelate. Abdomen with 3 somites or with 1-2 somites. Epimera present or absent. Pleopods present, 5 pairs; well developed, broad and flat; first pair or first and second pair forming an operculum; pleopod 2 forming a gonopod (eg. appendix masculina) in males. Uropods well developed, 1 pair, positioned ventrolaterally or positioned terminally or subterminally; rami present; endopod without statocyst. Telson fused to pleon (pleotelson).

Larval development. Epimorphic. Embryos carried in ventral thoracic brood pouch.

Habitat. Marine; freshwater.

Distribution. Worldwide.

Cite this publication as: Lowry, J.K. (1999 onwards). 'Crustacea, the Higher Taxa: Description, Identification, and Information Retrieval.' Version: 2 October 1999.