Phylogeny of the genus Pseudosinella (Hexapoda, Collembola) from the Western Carpathians caves reveals Miocene diversification

The observations from the recent period revealed that the Western Carpathians, a part of the Carpathian mountain chain, is the northernmost region in Europe with the occurrence of the obligate cave fauna. The collembolan genus Pseudosinella Schäffer, 1897 is a polyphyletic taxon derived from the genus Lepidocyrtus Bourlet, 1839 from which it differs in reduced number of eyes. It covers about 350 species with predominantly Holarctic distribution of which about 39% are confined to caves. We studied the morphology and molecular traits to identify cave species of the genus Pseudosinella occupying the Western Carpathian caves and clarify their phylogenetic relationships. Based on morphological traits we hypothesized that Pseudosinella aggtelekiensis (Stach, 1929) and P. paclti Rusek, 1961 are descendants of the different phyletic lineages, the former species lacking morphologically related edaphic species. On the other hand, several species related to P. paclti were found in caves, superficial subterranean habitats and in the soil. Molecular phylogeny analysis has shown two distinct groups of cave species following pattern of allopatric distribution. The first group consisted of populations of P. aggtelekienis from the Slovak Karst and an undescribed species from fragmented and isolated karst in eastern Slovakia. In the second group different populations of P. paclti occupying caves of the central karst regions were incorporated together with a new highly troglomorphic species confined to a small karst area. After an approximate estimate of the geological timing of the species isolation (RelTime), the two distinct Pseudosinella lineages separated approx. 9.54 mya followed by subsequent diversification in P. paclti lineage 8.36 mya, and in P. aggtelekiensis lineage 6.99 mya. This study contributed to assumption that the Western Carpathian Mts played an important role as speciation centre of the obligate cave fauna in Europe.