Key to the known species of Bythonia Oman

1 Shaft of aedeagus with two subapical spine-like processes laterally or ventrally............................................................................. 2

1’ Shaft of aedeagus without subapical processes .................................................................................................... kalypso Linnavuori

2 Subapical processes of aedeagus located laterally ........................................................................................................................... 3

2’ Subapical processes of aedeagus located ventrally ........................................................................................................................... 4

3 Ventral margin of pygofer with a spine-like process................................................................................. consensa Blocker & Webb

3’ Ventral margin of pygofer unarmed ..................................................................................................... ferruginea Felix & Mejdalani

4 Subapical processes of aedeagus detached from shaft, divergent from each other................................................... rugosa (Osborn)

4’ Subapical processes of aedeagus adpressed to shaft, very close together, almost indistinguishable from each other at low magnifi- cation ......................................................................................................................................................................... freytagi sp. nov.