DESCRIPTION OF 4 NEW GENERA OF THRAULUS GROUP MAYFLIES FROM THE EASTERN-HEMISPHERE AND REDESCRIPTION OF SIMOTHRAULUS AND CHIUSANOPHLEBIA (EPHEMEROPTERA, LEPTOPHLEBIIDAE, ATALOPHLEBIINAE)

Four new genera of Thraulus group mayflies (Ephemeroptera: Leptophlebi idae: Atalophlebiinae) from Malaysia, Papua New Guinea, and the Philip pines are established based on external morphological characters. All known life stages are described, diagnostic characters are illustrated , and keys to polytypic genera are provided. These four new genera com prise six species, four of which were previously assigned to Thraulus and two of which are new. The genera Simothraulus from Malaysia and Ch iusanophlebia from Japan are also redescribed. Thraulus group mayflies possess three derived character states: an oblique cross vein is loca ted in the fore wings between veins R4+5 and MA1, just apical to the f ork in vein MA; vein MA of the fore wings is symmetrically forked; and the gills are fimbriate.