Les bourdons de la Corse (Hymenoptera Apoidea, Bombinae).

The authors provide a complete revision of the Corsican bumble-bee fauna: illustrated key, synonymy, flowers preferences, distribution maps. Faunistic affinities of the 11 Corsican taxa are discussed. Six are good endemic taxa: Bombus perezi (Schulthess-Rechberg) (=Psithyrus perezi), Bombus terrestris xanthopus Kriechbaumer, Bombus lucorum renardi Radoszkowski, Bombus ruderatus corsicola Strand, Bombus hortorum jonghei ssp. nov. and Bombus pereziellus (Skorikov) comb. nov.; their taxonomic status is discussed. All these endemic taxa show a converging colour pattern, dark body with red or tawny abdomen tip and more or less reddish legs, which is very different from their continental vicariant taxa. Two taxa, Bombus maxillosus italicus (Griitte) (=Psithyrus m. italicus) and Bombus pascuorum melleofacies Vogt, are subspecies which are also widespread in Central and South Italy. They are probably recent well established immigrants in Corsica. Two taxa, Bombus terrestris sassaricus Tournier and Bombus ruderatus sardiniensis Tournier, seem to be occasional invaders in South Corsica from Sardinia, hybridizing with the corresponding endemics taxa, xanthopus and corsicola. Three taxa, Bombus terrestris terrestris auct., Bombus pratorum (L.) and Bombus hortorum hortorum (L.), were observed just once on Corsican coasts. They are recent non successfully accidental invaders. There are two characteristic bumble-bee communities in Corsica: a low Mediterranean (characteristic species : Bombus ruderatus corsicola and Bombus pereziellus) and a mountain community (characteristic species : Bombus lucorum renardi and Bombus hortorum jonghei). These two communities are overlapping in the high Mediterranean zone. As it can be seen everywhere, Bombus terrestris xanthopus is more ubiquitous than the related continental subspecies. Resource partitioning theories of INOUYE, RANTA and RANTA and VEPSALAINEN are discussed. The INOUYE'S theory (no more than 4 bumble-bee species in a community) seems to be right only in the low Mediterranean and in the mountain zones. In the intermediate high Mediterranean zone, the community structure is more in agreement with the RANTA and VEPSALAINEN's theory. It can probably be explained by a greater spatial and temporal zonal heterogeneity introduced by human activities and by floating limits between the Mediterranean and the mountain climates. Origins of the Corsican bumble-bee population are discussed. Evidences seem to show that the ancestors of the endemic taxa have invaded Corsica through a Corsica-Toscana gap, including Isola Capraia and Isola d'Elba. This gap did not need to be complete, bumble-bees being proved to be able to fly through large see channels. Tertiary Mediterranean events like continental drift and Messinian crisis can not have been responsible of the present bumble-bees distribution since modern taxa seem to have appeared more recently, during the last Ice-ages.