Rhithrogena
Figures: 23-24, 55, 115, 116, 121, 127, 168-170, 182, 212, 239
In addition to the Rhithrogeninae characteristics, the following combination of characteristics will identify the genus:
Larval Diagnosis
The presence of a well-developed median caudal filament and a ventral friction disk formed by the gills (Fig. 24) will differentiate larvae of Rhithrogena from all other Rhithrogeninae.
Adult Diagnosis
Males of Rhithrogena are identified by the combination of having a transverse suture on the mesonotum (Fig. 115), penes without median titillators (Fig. 168-170), and lateroparapsidal sutures that are strongly bent laterally (Fig. 116). North American females differ from all other genera by having strongly bent lateroparapsidal sutures and a rounded or truncate subanal plate (Fig. 212).
Distribution
Holarctic; Oriental (Fig. 239).
