Crustacea, the Higher Taxa

J.K. Lowry

Harpacticoida (Copepoda, Maxillipoda)

Description. Head. Rostrum present; head. articulated, or fused to head; eyes absent; eyes naupliar eyes present. Antennules (antenna 1) uniramous; geniculate in males; peduncle and flagellum indistinguishable; exopod well developed, whip-like, with 5-14 articles. Antennae (antenna 2) biramous, or uniramous, or reduced, vestigial or absent; exopod with 1 article, or exopod with 2 articles, or exopod with 3 articles, or exopod with 4 articles, or exopod with 8 articles, or exopod vestigial or absent; endopod with 3 articles. Mandible biramous, or uniramous; palp present, or absent. Maxillipeds, 1 pair; uniramous. Thorax. Carapace absent. Thorax and abdomen differentiated, boundary between fourth and fifth pedigerous somites (podoplean tagmosis). Peraeopods (legs) 6 pairs; biramous, or uniramous; non-phyllopodous; differentiated (some prehensile); each article joined by intercoxal sclerite; anterior peraeopods (swimming legs) with 1 robust seta on outer margin of exopod article 1. Abdomen with 5 somites (or fewer). Epimera absent. Pleopods absent. Uropods well developed, 1 pair, positioned terminally or subterminally; rami absent; subrectangular to subquadrate. Telson absent.

Larval development. Metamorphic. Embryos carried in paired or single sacs attached to first abdominal somite.

Habitat. Marine, brackish, freshwater benthic; usually free-living, occasionally parasitic.

Remarks. One of the few obvious differences between harpacticoid copepods and poecilostomatoid copepods is the number of articles in the exopod of the antennae (antenna 2). Generally harpacticoids have an exopod on the antennae and in poecelostomatoids the exopod is absent. But within the Harpacticoida most species of Ancorabolidae do not have an exopod and the entire antennae is absent in the cerviniid genus Tonpostratiotes. Consequently it is not possible to separate these two orders based on diagnostic characters.

Distribution. Worldwide.

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