alternative definition added over 13 years ago by Istvan Miko
forward extension of hypostoma, which on reaching underside of clypeus isolates mandibular socket from oral fossa; not clearly visible unless mandibles are spread.
Reference: Bohart, R. M., and A. S. Menke. 1976. Sphecid Wasps of the World, A Generic Revision. University of California Press, Berkeley, CA 695 pp.
Cross reference: false