Taxonomy of Oncaeidae (Copepoda, Poecilostomatoida) from the Red Sea. VI. Morphology and zoogeography of Oncaea bispinosa sp. nov., a sistertaxon of O. zernovi Shmeleva

Abstract

A new small species of oncaeid copepods, Oncaea bispinosa, is described from the Red Sea. It is closely related to O. zernovi Shmeleva, which is known from the Atlantic and the Mediterranean. The two species can be separated mainly by the outer spine count on the distal exopod segment of the second swimming leg, which shows two spines in O. bispinosa, but three spines in O. zernovi. A neotype of O. zernovi, for which type material is no longer extant, was designated. Oncaea tenella sensu Malt et al. and O. tenella var. pacifica Olson are regarded as junior subjective synonyms of O. zernovi. First data on the zoogeographical distribution of the two species, which seem to be geographically separated, are provided by examination of material from the northeastern Atlantic, the Indian Ocean and the Pacific. The ecological importance of species of the zernovi-type, which appear to be one of the most numerous microcopepod species in tropical/subtropical areas, is emphasized.