Bibio incrassatus Heer, 1849: 221 .

Described from a single specimen from “k.k. montan. Cabinet” Vienna. The specimen was depicted by Heer (Pl.

XVI Fig. 12) but it is difficult to tell what it is. Heer’s figure may suggest the presence of a vein R 2+3 and a vertical crossvein R-M, in which case the species should be placed in the genus Plecia, possibly as a synonym of Plecia

morio. On the other hand, if this interpretation of the wing venation is incorrect, it may habitually resemble Bibio

giganteus. Pongracz (1928: 183) considered Bibio morio and Bibio incrassatus as probable synonyms.