Lasius nitidigaster n.sp. - a new ant of the subgenus Chthonolasius Ruzsky [Hymenoptera: Formicidae]

A taxonomic description of Lasius nitidigaster n. sp., a temporary social parasite with mainly subterranean life, is given. Diagnostic characters separating it clearly from other species of the subgenus Chthonolasius are described for all three castes. A morphometric argumentation, based on a comparison of a queen sample of L. nitidigaster with the type queen of Lasius rabaudi, Bondroit 1917 gives strong evidence that both taxa cannot be regarded as synonyms. L. rabaudi represents a SW European or Iberian species while L. nitidigaster is of Balcan origin and goes north to E Austria and S Moravia.