Phylogenetic relationships among bumble bees (Bombus Latr.): a re-appraisal of morphological evidence
Williams, P. H. (1995)
Systematic Entomology, 19(1994): 327-344.
Cladistic analyses of morphological characters of adult bumble bees show significantly higher congruence among characters of the male genitalia than among other characters of males and females. Phylogenetic interpretations of groups supported by the combined morphological evidence (even with minimal assumptions) include (1) that the earliest diverging species belong to the paraphyletic subgenus Mendacibombus, together with Bombus nevadensis and B. confusus; (2) that, in contrast, species of the subgenus Bombus (sensu stricto) share a relatively recent common ancestor with B. pressus and B. rufipes; and (3) that Psithyrus (the social parasites) is a monophyletic group, and the sister-group of B. persicus. For genus-group nomenclature a single genus Bombus (sensu lato) is recommended, to include Psithyrus as another subgenus. Names for sections and for groups of subgenera are synonymized with subgeneric names.