Genus Polyergus Latreille

The members of this genus are obligate slave­raiders of other ants, mostly species in the Formica fusca ­group. The California populations of Polyergus are here treated as a single variable species, P. b re v i c e p s Emery. This implies synonymy of P. laeviceps Wheeler (type locality: Mt. Tamalpais, California) under P. breviceps but no formal change is proposed here because the entire complex needs comprehensive taxonomic evaluation. Within California there is considerable interregional variation in worker morphology and biology (including the host species attacked), but I have seen no evidence of more than one species occurring in any given locality. One might expect there to be pronounced interpopulation variation in P. b re v i c e p s because of the limited dispersal of the queens (Topoff 1999). References (partial list): Agosti (1994b), Creighton (1950a), Greenberg et al. (2004), Hasegawa et al. (2002), Hölldobler (1985), Topoff (1990, 1999), Wheeler (1968).