Figures: 81, 140-143, 180-181, 213, 220
In addition to the Rhithrogeninae characteristics, the following combination of characteristics will identify the genus:
Larvae of Cinygmula can be identified by the combination of having the anterior margin of head capsule emarginate, lacking interfacing setae on the caudal filaments, and lacking a ventral friction disk formed by the gill lamellae. In most species, the maxillary palps protrude beyond the lateral margins of the head capsule in dorsal view. Many Rhithrogena larvae also have a median excavation on the anterior margin of the head capsule, but differ from larvae of Cinygmula in having a ventral friction disk formed by the gill lamellae.
Males of Cinygmula are differentiated from other Rhithrogeninae by the combination of having a transverse suture on the mesonotum (as in Fig. 115), median titillators on the penes that are not strongly bent laterally (Figs. 140-143), and lateroparapsidal sutures that are bent laterally (as in Fig. 116). The laterally bent lateroparapsidal sutures distinguish North American females of Cinygmula from all othe Rhithrogeninae except Rhithrogena, but they can be differentiated from that genus by the distinctly emarginate subanal plate (Fig. 213).
Holarctic; Oriental (Fig. 220).