SYSTEMATIC REVISION OF THE THRAULUS GROUP GENERA (EPHEMEROPTERA: LEPTOPHLEBIIDAE: ATALOPHLEBIINAE) FROM THE EASTERN HEMISPHERE (PHYLOGENY, CLADISTICS, TAXONOMY)

A taxonomic revision and phylogenetic reconstruction of the Thraulus group genera and their species was carried out based upon the examination of external morphological characters. Nine new taxa are described (four genera and five species) and four species previously assigned to Thraulus have been reassigned to these new genera. Seven species remain assigned to Thraulus. Simothraulus remains monotypic. The five species of Neotropical Thraulus have been reassigned to other Central and South American genera, making the distribution of the Thraulus group genera exclusive to the Eastern Hemisphere. Keys to genera and species for known imagos and nymphs are provided, and diagnostic characters are illustrated.; Cladistic methodology was used to reconstruct the probable phylogeny of the Thraulus group genera and their species. The South American Ulmeritus group was identified as the sister group of the Thraulus group genera, as both share the following derived character states: the fork of vein MA of the fore wings is symmetrical, an oblique cross vein occurs in the fore wings between veins R(,4+5) and MA(,1) just apical to the fork of vein MA, and the abdominal gills are fimbriate. The Thraulus group genera share the following derived character states: vein Sc of the hind wings ends at the base of the costal projection, the apical margin of the lingua of the hypopharynx is bare, and nymphs have posterolateral spines on abdominal terga 6-9, 7-9, or 8-9. Species unknown in the nymphal stage could not be confidently placed in the phylogeny. Two parallelisms have occurred among the species of Thraulus: the loss of the row of setae on the lateral margin of the mandibles at the base of the incisors and the reduction in both lamellae of abdominal gill 1.