Revision of the South American species of Leptohyphes Eaton (Ephemeroptera: Leptohyphidae) with a key to the nymphs

The male imago of Leptohyphes eximius Eaton, 1882 (type species of the genus) and male and female adults of L. cornutus Allen (1967) and L. plaumanni Allen (1967) are described for the first time. The nymphs of these species are redescribed. A new generic definition is proposed to include all the stages. Characters for separating male, female, eggs and nymphs of this genus from the other genera of the family are discussed and illustrated. Cotopaxi Mayo (1968) is proposed to be a junior synonym of Leptohyphes Eaton; its type species C. macuchae is declared a Nomen Dubium. The type material of all the South American species of Leptohyphes described as nymphs was studied, and a key together with a diagnosis with illustrations are presented for them. The following new synonymies are proposed: Leptohyphes eximius Eaton (= L. bruchi Navas and Bruchella nigra Navds), L. maculatus Allen (= L. comatus Allen, L. hirsutus Allen & Roback and L. myllonotus Allen & Roback), L. setosus Allen (= L. echinatus Allen & Roback), L. tacajalo Mayo (= L. albus Mayo) and L. plaumanni Allen (= L. pereirae da Silva). After this revision the number of valid South American species of Leptohyphes is eighteen (18). Scanning microscope photographs of the eggs of two species: L. eximius and L. cornutus are presented.