Three new genera of small minnow mayflies (Insecta : Ephemeroptera : Baetidae) from the Andes and Patagonia

Three new genera and three new species of Baetidae (Insecta: Ephemeroptera) are described from the Andes and Patagonia. Larvae of Andesiops, new genus , are distinguished by the apically bifid right prostheca and two rows of d enticles on the tarsal claws. Larvae of Deceptiviosa, new genus, are distin guished by the apically bifid right prostheca and small subapical denticle on the tarsal claws. Larvae of Nanomis, new genus, are distinguished by the apically acute maxillary palp segment 2, smooth posterior margin of the te rga, and paddle-shaped subapical seta on the hindtibiae. Adults of Andesiop s and Deceptiviosa are similar, but distinguished from other South American baetids by having hindwings with a small costal process in the basal one t hird and three longitudinal veins with the middle vein being forked, and an elongate and ellipsoidal genital forceps segment 3. Larvae and adults of A ndesiops peruvianus, new combination, are redescribed, and additional local e data are provided for Argentina, Bolivia, Ecuador, and Venezuela. Decepti viosa ardua, new species, is described from larvae from Chile, and D, torre ns, new species, is described from larvae and adults from Chile and Argenti na. Nanomis galera, new species, is described from larvae from Argentina, C olombia, Ecuador, and Peru.