Abstract
We revise the Bibionidae fauna from the Pliocene Fossil-Lagerstätte Willershausen (Germany), the youngest known fossil site containing Bibionidae in Europe. The material includes about 75 bibionid specimens, mostly females. The preservation is generally good for wings, whereas other body parts are less well preserved. Two new species, Dilophus flavipes sp.n. and Dilophus plionanus sp.n., are described. Bibio tenuis Dürrenfeldt, 1968, is moved to the genus Dilophus and renamed Dilophus duerrenfeldti nom.n. as it will be a junior homonym of Dilophus tenuis Meigen, 1818. Bibio anasiformis Dürrenfeldt, 1968 is moved to the genus Dilophus and renamed Dilophus anasiformis comb.n. The following new synonymies are established (senior name listed first) Bibio enormus Dürrenfeldt, 1968 = Bibio latiantennatus Dürrenfeldt, 1968 = Bibio medioalbus Dürrenfeldt, 1968 = Bibio soldatus Dürrenfeldt, 1968; Bibio contererus Dürrenfeldt, 1968 = Bibio mancus Dürrenfeldt, 1968 = Bibio dormitus Dürrenfeldt, 1968 = Bibio tripus Dürrenfeldt, 1968 = Bibio carnificus Dürrenfeldt, 1968 = Bibio constringtus Dürrenfeldt, 1968; Bibio acaptus Dürrenfeldt, 1968 = Bibio deflectus Dürrenfeldt, 1968 = Bibio similis Dürrenfeldt, 1968; Bibio nebulosus Dürrenfeldt, 1968 = Bibio vixdus Dürrenfeldt, 1968 = Bibio cruciformis Dürrenfeldt, 1968 = Bibio albangulus Dürrenfeldt, 1968. Plecia sp. of Dürrenfeldt (1968) is reinterpreted as Penthetria sp., but not formally named. We give a key to the species. The material from Willershausen includes the largest known species of Bibionidae, fossil or recent, but also one of the smallest known species.