Relationships among the major subgroups of Brachycera (Diptera): A critical review.

Six major subgroups of the Brachycera are recognized under the names Stratiomyomorpha, Vermileonomorpha new infraorder, Tabanomorpha, Nemestrinoidea, Pleroneura, and Eremoneura. Recent suggestions regarding the possible sister-group of the Brachycera are reviewed, and all found to be inadequately supported. Characters used to support possible relationships between the major subgroups (i.e. possible synapomorphies) are reviewed with respect to morphological interpretation and polarity. On the basis of this analysis, five partly conflicting possible groupings are discussed: (1) all other Brachycera as the sister-group of the Stratiomyomorpha; (2) Muscomorpha sensu Woodley (Nemestrinoidea + Heterodactyla); (3) inclusion of Nemestrinoidea in Tabanomorpha; (4) Heterodactyla sensu Lameere (Pleroneura + Eremoneura); and (5) an asilotabaniform group (Vermileonomorpha + Tabanomorpha + Nemestrinoidea + Pleroneura). Resolution of conflicts among these possible groupings will require critical morphological studies of the phallic complex and embryological studies of groups of Brachycera other than Cyclorrhapha. Because of present uncertainties, it is recommended that authors consider alternatives rather than rely on a single preferred concept of phylogeny at this time. Autapomorphies of the major subgroups are discussed in an appendix.