Unexpected diversity in the relictual European spiders of the genus Pimoa (Araneae : Pimoidae)

Abstract

Pimoidae is a small family of araneoid spiders, hitherto represented in Europe by two species with disjunct distribution in the Alps and in the Cantabrian Mountains of northern Spain. Here we report the description of two additional European species of Pimoa, discovered within the range of the only former alpine species, P. rupicola: P. graphitica sp. nov. and P. delphinica sp. nov. The new species are distinguished from the latter by genitalic characters as well as by molecular characters. On the basis of the re-examination of old and recent abundant material collected in caves and other subterranean habitats, we revise the distribution patterns of the genus Pimoa in the Alps and outline the species distribution ranges. Molecular data suggest the existence of gene flow between populations of the two new species when in sympatry. The different species probably originated in the alpine region as a result of range contractions following dramatic climatic changes in the Alps since the mid Miocene. We interpreted the present-day overlapping distribution in light of a possible postglacial expansion. Finally, we provide insights on the natural history and life cycles of the new species and discuss their phylogenetic relationships within Pimoidae.