Figures: 28, 36-37, 73, 79, 106, 172, 243
In addition to the Ecdyonurinae characteristics, the following combination of characteristics will identify the genus:
The combination of having a distinctly thickened anterior margin of the head capsule (Figs. 36-37), long posterolateral spines on the abdomen (Fig. 106), acutely pointed supracoxal spurs (Fig. 79), and well-developed lamellae on gills 1 will distinguish Thalerosphyrus from other Ecdyonurinae genera. Larvae of Thalerosphyrus are most similar to larvae of Atopopus. Atopopus differs in having rounded supracoxal spurs and minute lamellae on gills 1. Larvae of Compsoneuria had previously been confused with those of Thalerosphyrus because they also have acutely pointed supracoxal spurs, but Compsoneuria larvae do not have a thickened anterior margin of the head capsule or long posterolateral spines on the abdomen, and have narrowed glossae and black spotting on the head capsule and femora. Unlike other species in Thalerosphyrus, larvae of the type species, T. determinatus (Walker) have only slightly produced supracoxal sclerites, although they are still acutely pointed. Wang and McCafferty (2004) noted that Ulmer (1939) possibly misassociated the larvae and adults of T. determinatus but we have recently obtained reared specimens that show Ulmer's (1939) association was correct.
Males of Thalerosphyrus are unique among the Ecdyonurinae in lacking apical sclerites on the penes (Fig. 172).
Oriental (Fig. 243).