A multigene species tree for Western Mediterranean painted frogs (Discoglossus)

Painted frogs (Discoglossus) are an anuran clade that originated in the Upper Miocene. Extant species are morphologically similar and have a circum-Mediterranean distribution. We assembled a multilocus dataset from seven nuclear and four mitochondrial genes for several individuals of all but one of the extant species and reconstructed a robust phylogeny by applying a coalescent-based species-tree method and a concatenation approach, both of which gave congruent results. The earliest phylogenetic split within Discoglossus separates D. montalentii from a clade comprising all other species. Discoglossus montalentii is monophyletic for haplotype variation at all loci and has distinct morphological, bioacoustic and karyotypic characters. We find moderate support for a sister-group relationship between the Iberian taxa and the Moroccan D. scovazzi, and high support for a D. pictus – D. sardus clade distributed around the Tyrrhenian basin. Topological discordance among gene trees during the speciation of D. galganoi, D. scovazzi, D. pictus and D. sardus is interpreted as the consequence of nearly simultaneous, vicariant diversification. The timing of these events is unclear, but possibly coincided with the final geotectonic rearrangement of the Western Mediterranean in the Middle Miocene or later during the Messinian salinity crisis. The Iberian taxa D. galganoi galganoi and D. g. jeanneae are reciprocally monophyletic in mitochondrial DNA but not in nuclear gene trees, and are therefore treated as subspecies of D. galganoi.