A remarkable new genus of Atalophlebiinae (Ephemeroptera: Leptophlebiidae) from the Neotropics

An unusual species of Leptophlebiidae is described based on males, females, and nymphs from Rio de Janeiro State, Brazil. As a consequence of its distinct characteristics on all stages, a new genus is established. The new genus can be distinguished from other South American Leptophlebiid genera mostly by: Adults: vein MA of fore wings asymmetrical; hind wings with costal projection well developed, Sc ending at cross vein near costal projection; tarsal claws dissimilar, one blunt other acute; projections of styliger plate forming two well developed lobes with rounded apex, ventrally obstructing view of the penes; penes fused on basal half, each lobe with a ventral furrow and a long and slender spine directed anteriorly. Nymphs: Head prognathous, wider than labrum; labrum with prominent median emargination, with three subtle crenulations; body flattened; hind wings pads present; tarsal claws with over 20 denticles, subapical denticle much larger than remaining denticles; gills long and narrow, present on abdominal segments I-VII; posterolateral projections present on abdominal segments VIII-IX. Phylogenetic analyses conducted based on a previously published data matrix that included other South America leptophlebiid genera placed Poranga nessimiani gen. nov. et sp. nov. as sister to Bessierus + Perissophlebioides. In most analyses this clade was recovered within the Farrodes complex. Nymphs of the new taxa are particularly similar to Bessierus, whereas adults share the very acute costal projection on hind wings seen in non-dipterous members of the Farrodes complex.