Call a spade a spade: taxonomy and distribution of Pelobates, with description of a new Balkan endemic

Abstract

The genomic era contributes to update the taxonomy of many debated terrestrial vertebrates. In an accompanying work, we provided a comprehensive molecular assessment of spadefoot toads (Pelobates) using genomic data. Our results call for taxonomic updates in this group. First, nuclear phylogenomics confirmed the species-level divergence between the Iberian P.cultripes and its Moroccan relative P.varaldii. Second, we inferred that P.fuscus and P.vespertinus, considered subspecies until recently, feature partial reproductive isolation and thus deserve a specific level. Third, we evidenced cryptic speciation and diversification among deeply diverged lineages collectively known as Pelobatessyriacus. Populations from the Near East correspond to the Eastern spadefoot toad P.syriacus sensu stricto, which is represented by two subspecies, one in the Levant (P.s.syriacus) and the other in the rest of the range (P.s.boettgeri). Populations from southeastern Europe correspond to the Balkan spadefoot toad, P.balcanicus. Based on genetic evidence, this species is also polytypic: the nominal P.b.balcanicus inhabits the Balkan Peninsula; a new subspecies P.b.chloeaessp. nov. appears endemic to the Peloponnese. In this paper, we provide an updated overview of the taxonomy and distribution of all extant Pelobates taxa and describe P.b.chloeaessp. nov.

Phylogeography of a cryptic speciation continuum in Eurasian spadefoot toads (Pelobates)

“…Nevertheless, our best‐supported topologies, which group P. syriacus s.s . and P. balcanicus as sister clades (Figure , Figure ), are consistent with morphological similarities (Dufresnes et al, ), as well as a previous mitochondrial phylogeny (Veith et al, ; with similar divergence time estimates). Future fine‐scale sampling at their contact zone will be required to understand whether these form very localized hybrid zones, and if premating barriers evolved between these cryptic species.…”

“…Cloudograms are available in Figure . The map shows the distribution of all Pelobates taxa (Dufresnes et al, ). The top left picture illustrates the new Peloponnese subspecies P. b. chloeae discovered by this work (photo credit: C.D.…”

“…Dots are coloured according to mtDNA lineages. The map shows the distribution of all Pelobates taxa (Dufresnes et al, ). Note that the ranges of P. vespertinus and P. s. boettgeri extend further east…”

“…Important localities are highlighted on the maps and structure barplots. The small framed maps show the distribution of all Pelobates taxa (Dufresnes et al, )…”

“…Fourth and fifth, the Pleistocene clades discovered within P. balcanicus (~2 My) and P. syriacus s. s . (~1 My), that we consider as subspecies (Dufresnes et al, ), potentially admix over wide areas, indicative of little or no hybrid incompatibility. In the Balkans, hybridization was detected in one locality between P. b. balcanicus and P. b. chloeae (loc.…”