Mimumesa littoralis (Bondroit), M-oresterus (van Lith), and M-unicolor (Vander Linden): notes on similarity, synonymy, and identification (Hymenoptera : Crabronidae)

Mimumesa oresterus (van Lith) was found to be less different from regional populations of M. unicolor (Vander Linden) than are regional populations of the closely related species M. littoralis (Bondroit) among themselves, and M. oresterus is therefore synonymized with M. unicolor. The East Asiatic p opulation of M. littoralis is comparatively dissimilar to conspecific Europ ean and Central Asiatic populations morphometrically and in some details of male genitalia, and after additional studies it might be considered as a s ubspecies. An identification key with new structural and morphometric chara cters to distinguish M. littoralis and M. unicolor is presented.