Systematics of the Nearctic granivore ant genus Veromessor (Hymenoptera: Formicidae)

Veromessor, a Nearctic genus of harvester ants with nine species, is here restored from synonymy with the granivore ant genus Messor, which is then left with 94 Old World species. A data matrix of 69 morphological characters from all three castes was assembled for 22 terminal taxa to reconstruct the phylogeny, to test the monophyly, and to determine the sister group for Veromessor. Terminal taxa included the ingroup, Veromessor, and thirteen outgroup taxa chosen from the genus Aphaenogaster and the Old World species of Messor. The full matrix and thirty-four partitions of the matrix (based on different taxon and character sets) were analyzed.; The resulting tree showed that Veromessor is monophyletic and its sister taxon is the Aphaenogaster albisetosa group, rather than species of Messor. Many Messor species were found to belong to a single clade, here designated as the M. barbarus group. The internal phylogeny of Veromessor was fully resolved and showed several well-supported clades, whose present distributions correspond with modern distributions of particular xeric floristic provinces.