Title: Phylogenetic inferences on West Mediterranean Ditomina (Coleoptera: Carabidae: Harpalini) based on molecular data

Ditomina is a subtribe of ground beetles included in the large tribe Harpalini, with most species restricted to the Mediterranean basin. To date, affinities within Harpalini have mainly been derived from morphological data, and the placement of several genera within Ditomina has been subject to discussion. In this study we provide a regional molecular phylogeny for Ditomina with representatives from seven of the eight known genera from the West Mediterranean region, the Australian Phorticosomus Schaum, 1862, and selected Harpalini outgroup taxa. DNA sequences from two different markers, the mitochondrial protein coding gene cox1 and the nuclear gene ITS2, were sequenced and analysed from 19 taxa. Molecular phylogenetic analyses consistently support (i) the sister relationship of genera Carterus Dejean, 1830 and Eocarterus Stichel, 1923- (ii) a close relationship among Ditomus Bonelli, 1810, Tschitscherinellus Csiki, 1906 and Odontocarus Solier, 1835, which form a lineage well separated from Dixus Billberg, 1820- and (iii) the exclusion of Graniger Motschulsky, 1864 and the Australian Phorticosomus from the subtribe Ditomina. In addition, phylogenetic trees indicate a vicariance event for the brachypterous genus Eocarterus on both sides of the Strait of Gibraltar, followed by further geographical differentiation in southern Iberia and northern Morocco. This pattern contrasts with the distribution of various fully winged species of ground beetles on both sides of the same barrier, suggesting the role of dispersal limitation in speciation. Finally, a new key to supraspecific taxa of the Ditomina of the West Mediterranean region is provided.