Reevaluation of the Phylogeny of the Drosophila virilis Species Group (Diptera: Drosophilidae)

The phylogeny of the Drosophila virilis species group was reevaluated by analyzing all previously published data sets. These included 1 developmental, 4 morphological, 6 chromosomal, 7 behavioral, and 10 molecular studies that have examined the group in a comparative way. It was concluded that there are four monophyletic clades within the D. virilis species group: (1) the virilis phylad, which includes D. virilis Sturtevant, D. lummei Hackman, D. novamexicana Patterson, D. americana Spencer, and D. texana Patterson; (2) the montana subphylad, which consists of D. montana Stone, Griffen & Patterson, D. lacicola Patterson, D. borealis Patterson, and D. flavomontana Patterson; (3) the littoralis subphylad consisting of D. littoralis Meigen and D. ezoana Takada & Okada; (4) and the monotypic kanekoi subphylad which includes D. kanekoi Watabe & Higuchi. The consensus phylogeny produced by this reanalysis does not support some of the systematic relationships that are currently accepted. The major division within the group, between the virilis phylad and the montana phylad (which consists of the montana, littoralis, and kanekoi subphylads), is found to be unsupported because in some reanalyses the littoralis and kanekoi subphylads cluster with the virilis phylad, and not the montana phylad. Consequently, the relationships among the phylads and subphylads are considered unresolved. The relationships of the virilis phylad are consistent with previous analyses, although the relationships among D. americana , D. texana , and D. novamexicana are considered unresolved based on the character evidence. Within the montana subphylad the only stable relationship appears to be the ancestral position of D. flavomontana relative to the other species in the subphylad.