Molecular systematics of basal subfamilies of ants using 28S rRNA (Hymenoptera: Formicidae)

Abstract

For many years, the ant subfamily Ponerinae was hypothesized to contain the basal (early branching) lineages of ants. Recently the Ponerinae were reclassified into six poneromorph subfamilies based on morphological analysis. We evaluate this new poneromorph classification using 1240 base pairs of DNA sequence data obtained from 28S rRNA gene sequences of 68 terminal taxa. The molecular tree supported the monophyly of the ant family Formicidae, with 100% parsimony bootstrap (PB) support and posterior probabilities (PP) of 1.00, with the ant subfamily Leptanillinae as a sister group to all other ants (PB = 62, PP = 93). However, our analyses strongly support the polyphyly of the Poneromorph subfamilies (sensu Bolton). The Ectatomminae and Heteroponerinae are more closely related to the Formicoid subfamilies than to the rest of the poneromophs (PB = 96, PP = 100). The Amblyoponinae (PB = 52, PP = 96), Paraponerinae (PB = 100, PP = 100), Ponerinae (PB < 50, PP = 71), and Proceratiinae (PB = 98, PP = 100) appear as distinct lineages at the base of the tree and are identified as a poneroid grade. Monophyletic origins for the poneroid subfamilies Amblyoponinae, Paraponerinae, Ponerinae and Proceratiinae are supported in our analysis. However, the genus Platythyrea forms a distinct sister group to the Ponerini within the Ponerinae. The Heteroponerinae, based on our sample of Heteroponera, are associated with the subfamily Ectatomminae (PB = 98, PP = 100). Furthermore, our data indicate the genus Probolomyrmex belongs to the Proceratiinae as suggested by recent morphological analysis (PB = 98, PP = 100).