Crustacea, the Higher Taxa

J.K. Lowry

Flabellifera (Isopoda, Peracarida, Malacostraca)

Description. Head. Rostrum absent; eyes sessile or absent; compound, visual elements present; ocular scale absent; naupliar eyes absent. Antennules (antenna 1) biramous, or uniramous; peduncle and flagellum distinct; endopod reduced, vestigial or absent; exopod well developed, whip-like or exopod reduced, vestigial or absent; statocyst absent. Antennae (antenna 2) uniramous; exopod multiarticulate. Mandible uniramous; palp present, or absent. Maxillipeds, 1 pair; uniramous. Thorax. Carapace absent. Thorax and abdomen differentiated. Peraeopods (legs) 7 pairs, or 6 pairs; uniramous; non-phyllopodous; undifferentiated (simple), or differentiated (some prehensile); some coxae forming lateral plates. Peraeopod 1 (leg 1) simple, or subchelate. Peraeopod 2 (leg 2) simple, or subchelate. Peraeopod 3 (leg 3) simple. Abdomen with 5 somites or with 4 somites or with 3 somites or with 1-2 somites. Epimera present. Pleopods present, 5 pairs; well developed, broad and flat; first or second pair not modified into operculum; pleopod 2 forming a gonopod (eg. appendix masculina) in males. Uropods well developed or vestigial or absent, 1 pair, positioned ventrolaterally; rami present, exopod without diaresis; endopod without statocyst. Telson fused to pleon (pleotelson).

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

Habitat. Marine, freshwater; free-living.

Remarks. According to Poore and Wilson (pers comm) the flabelliferan isopods are a polyphyletic group. According to Bruce (pers comm) one genus, Paraviriea Chilton, 1922, totally lacks uropods.

Distribution. Worldwide.

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