Figures: 3, 42, 59, 77, 85-86, 138, 216
In addition to the Ecdyonurinae characteristics, the following combination of characteristics will identify the genus:
Larvae of Asionurus are easily differtiated from those of all other Ecdyonurinae genera by the extremely long, narrow lamellae on gills 7 (Fig. 86). The acutely pointed posterolateral extensions of the superlinguae (Fig. 59) will also separate Asionurus from all other genera except Atopopus. The pectinate setae present on the tarsi of Asionurus (Fig. 77) appear to be unique. Larvae are superficially similar to those of Compsoneuria in their overall appearance and the presence of apically pointed, narrow glossae and convex anal margins on the lamellae of gills 1, but the characteristics listed above should separate the two.
The combination of the presence of medially situated titillators, red staining between the costa and subcosta of the forewings, and the lack of distinct lateral sclerites on the penes (Fig. 138) should identify males of Asionurus.
Southeast Asia (Fig. 216).