Abstract
In contrast to neighbouring Maghrebian countries and despite recent progress, knowledge of the Ephemeroptera of Algeria remains fragmentary. As part of an ongoing survey of the Ephemeroptera of Algeria, we investigated the mayfly fauna of Wadi Cherf, a major tributary of the Seybouse River, northeastern Algeria, and present an updated checklist and distribution of Ephemeroptera of this major Maghrebian river. Eighteen species were identified with new records for northeastern Algeria, filling distributional gaps. In addition, two species, Habrophlebia sp. and Procloeon sp., are new to science. A multivariate analysis indicated that mayfly assemblages of the Seybouse River were driven by the physical characteristics of habitats. Species richness was positively correlated with permanent flow and coarse substrate and negatively associated with altitude and salinity. Results also showed that Caenis luctuosa and Baetidae, in particular Baetis gr. pavidus and Cloeon gr. dipterum, dominated the mayfly community.