alternative definition added over 14 years ago by Andy Deans
The paired ventral ridges of the united second valvulae on which the first valvulae glide.
Reference: Ronquist, F., and G. Nordlander. 1989. Skeletal morphology of an archaic cynipoid, Ibalia rufipes (Hymenoptera: Ibaliidae). Entomologica Scandinavica, Supplement 33:1-60.
Cross reference:
None provided.