During the period 1990-1998, 51 samples of Collembola, family Entomobryidae, were made in continental Yemen, mostly in mountainous areas. Most samples were hand-collected by beating vegetation over a collecting tray, but other collecting methods, such as light-traps, Malaise-traps, pitfall- traps and Tullgren funnels, were also used. This paper only deals with the genus Seira Lubbock, 1869. Six species are described, one of which, Seira eleana Coates, 1968 is known from South Africa, whereas five are new species: S. polysperes n. sp., S. jacquemarti n. sp., S. yemenensis n. sp., S. humberti n. sp. and S. sanaaensis n. sp. Seira polysperes n. sp. is characterized by possessing seven inner mesothoracic setae (zone 3A), by strong pilosity of the area before the ventral tube, and by a variable pigmentation that does not fit within the variation of the nearest species, S. ferrarii Parona, 1888. Seira jacquemarti n. sp. can be distinguished from S. deserti Jacquemart, 1974, by possessing seven mesothoracic macrochaetae in zone 1 (A + B) and eight abdominal macrochaetae in zone a. Seira yemenensis n. sp. does not possess macrochaetae on abdominal segment I and generally its dorsal chaetotaxy is much reduced. Its specific pigmentation distinguishes S. yemenensis n. sp. well from all other species. Seira humberti n. sp. possesses abundant dorsal setae. The presence of 5 + 5 macrochaetae on abdominal segment I distinguishes it from the European species with higher numbers of setae on that segment. Seira sanaaensis n. sp. presents 5 + 5 macrochaetae on zone c of abdominal segment IV; this character and its weak pigmentation distinguish it from the nearest species, S. ferrarii Parona, 1888.
Collembola, Entomobryidae, Seira, Republic of Yemen, new species.