A New Species of Common Toads from the Talysh Mountains, South-Eastern Caucasus: Genome Size, Allozyme, and Morphological Evidences

Abstract

The genome size, protein (24 loci) and morphological variation in three currently recognized species of the Bufo bufo group was studied. Among common toads of the Caucasian Isthmus, two distinct groups were revealed. The main territory of the Caucasian region, including the Great Caucasian Range and the Caucasus Minor, is inhabited by the Caucasian toad, B. verrucosissimus , whereas the Talysh Mountains, geographically isolated in the south-east of the region, harbor another toad. Genetic distances between these forms were higher ( D = 0.411) than that between B. verrucosissimus and European B. b. bufo ( D = 0.138). Based on genome size and allozyme data, we recognized the Talysh toad as a new distinct species, Bufo eichwaldi , sp. nov. The time of origin of the species estimated on the basis of molecular data, roughly corresponds to relict character of the Hyrcanian forest of the Talysh region (the late Miocene). West Palearctic species ( B. bufo , B. verrucosissimus , B. eichwaldi , sp. nov.) form joint cluster which is separated from another phylogenetic lineage with the Far Eastern B. gargarizans . Taxonomic status of B. verrucosissimus and B. b. spinosus is discussed. The Caucasian toad was treated tentatively as an allopatric species in respect to B. b. bufo of boreal Europe. Common toads of Anatolian Turkey previously recognized as B. b. spinosus were assigned to B. verrucosissimus . The Balkan common toads seems to be a distinct taxon which is the sister lineage of the B. verrucosissimus cluster. Toads from Apennine Peninsula were allocated to distinct subspecies B. b. palmarum . North African (Tunisian) B. b. spinosus was separated as a distinct phyletic lineage forming with B. eichwaldi , sp. nov., the sister group of other West Palearctic common toads. Further resolution of the taxonomic position of that and some other members of the Bufo bufo group needs careful examination of samples from Mediterranean area, including the type locality of B. b. spinosus .