Abstract
Aturbina (Ephemeroptera: Baetidae), gen. n., is described from a single species, A. georgei sp. n., based on larvae and male and female adults from western Brazil, French Guiana, and Paraguay. Besides being the first baetid mayfly known to lack the turbinate portion of the male compound eyes, the genus is distinct in that larvae possess an elongate, distally branched seta at the base of the right prostheca and male adults have genital forceps with a distinct distomedial process on segment 1 and a highly reduced segment 3. Male and female adults are further distinguished by the possession of a small medial hump on the metanotum and a costal process with two peaks in the hindwings. The significance of the new baetid taxon is discussed.