Figure 4. Phylogeny of the Drosophila immigrans species group.

Phylogenetic tree produced by Bayesian analysis in MrBayes. Posterior probabilities at all nodes are >99%. This tree identifies three monophyletic clades: nasuta subgroup (1), immigrans subgroup (2), and hypocausta subgroup proper (3). Although D. ruberrima is traditionally assigned to the immigrans subgroup (De Meijere, 1911), our analysis places it as sister group to the nasuta subgroup (Node A). D. neohypocausta was originally described as part of the hypocausta subgroup (Osten Sacken, 1882), but here it is also placed closer to the nasuta subgroup (node B). The immigrans subgroup forms a monophyletic clade with the nasuta subgroup + D. ruberrima + D. neohypocausta (node C), and the hypocausta subgroup occupies the most basal position in the immigrans species group (node D). D. quadrilineata was used as an outgroup to root the tree.