Genomic evidence for cryptic speciation in tree frogs from the Apennine Peninsula, with description of a new species, Hyla perrini. Hyla intermedia and Hyla perrini

The data herein were used to describe the new species Hyla perrini. This data is accepted for publication in the journal Frontiers in Ecology and Evolution under the title: Genomic evidence for cryptic speciation in tree frogs from the Apennine Peninsula, with description of a new species, Hyla perrini.Abstract:Defining new species is a major yet necessary challenge in modern phylogeography in order to optimize conservation efforts. In amphibians, the lack of phenotypic differences among closely-related taxa, their complex, sometimes unsettled phylogenetic relationships, together with their potential to hybridize, is blurring taxonomic boundaries. Here we implement a multi-disciplinary approach to evaluate the nature of two deeply-diverged mitochondrial lineages previously documented in Italian tree frogs (Hyla intermedia s. l.), distributed north and south of the Apennine Mountains. Combining mitochondrial phylogenetics, nuclear phylogenomics, hybrid zone population genomics, niche modelling analyses, and biometric assessments, we provide evidence for these lineages to be considered distinct, cryptic species. We recovered two congruent mitochondrial and nuclear monophyletic clades, of mid-Pliocene divergence (~3.5 My), admixing only over a narrow transition restricted to Emilia Romagna (50-100km). These parameters are comparable to similarly-studied parapatric amphibians bearing a specific status. Inferred from their current geographic distribution, the two Italian tree frogs featured disruptive ecological niches (<15% of niche overlap), raising questions regarding potential adaptive components to their incipient speciation. However, we found little phenotypic differences, neither morphologically nor bioacoustically. These findings support a gradual buildup of reproductive isolation in Hyla, as inferred from hybrid zone analyses, and pinpoint additional cryptic lineages of similar divergence to be treated as separate species (H. c.f. meridionalis). We recommend such combined approaches and genomic resources for the future taxonomic assessment of cryptic diversity in alloparapatric radiations of terrestrial vertebrates, especially for controversial taxa. Finally the northern Italian tree frogs are formally described as a new species, Hyla perrini, sp. nov., a tribute to our beloved, recently-retired collaborator, Prof. Nicolas Perrin.