[Empidomermis riouxi n. sp. (Nematoda, Mermithidae). (author's transl)].

Empidomermis riouxi n. sp. is described from Aedes (Ochlerotatus) detritus, in Camargue. The species differs from E. cozi, which is the only other species of the genus, by having a sligtly larger size and a very little pronounced cephalic constriction. Males differ also from those of E. cozi by the number and disposition of the caudal papillae. The postparasitic larvae escape from adult mosquitoes, rarely from pupae. In laboratory conditions, the nematodes enter the moist sand in the bottom of Petri dishes where, after about 20 days, they molt, mate and oviposit. All the larval stages of A. detritus can be found infected. The presence of parasites induce the arrest of the ovarian development of the females and inhibits the mating activity of males. The rate of parasitism is very high and its fluctuations seem closely related to the host life cycle.