The West African species of Caenis Stephens (Insecta: Ephemeroptera)

The present paper is the result of the examination of several thousand specimens of the genus Caenis Stephens, 1835 (Ephemeroptera) which were collected in West Africa in more than 200 light trap samples from 32 rivers in Guinea, Mali, Ivory Coast, Togo and Ghana. Five new species are described: Caenis vermifera n. sp. (Ivory Coast, Guinea), C. nigricola n. sp. (Mali, Guinea), C. jinjanoides n. sp. (Guinea, Ivory Coast), C. kohli n. sp. (Guinea), and C. orthostilata n. sp. (Mali). The extensive materials allow to add distributional data to previously known species. C. elouardi, C. cibaria kunda, C. gilliesi, C. jinjana, C. antelucana, C. brevipes, C. berneri, and C. pallida are redescribed. The eggs of most of the treated species are described based on SEM pictures. Several questions concerning supposed species relationships are discussed. The subspecies rank of C. brevipes occidentalis Malzacher, 1993 ist rejected.