A troglobiotic oribatid mite (Acari, Oribatida) in European caves: cryptic diversity and a Late Miocene origin of its phyletic lineages

Populations of the highly cave-associated oribatid mite Kunstidamaeus lengersdorfi from the Western Carpathians, the Moravian Karst and the Harz Mountains, Central and Western Europe, were analysed using an integrative morphological-molecular approach involving mitochondrial and nuclear markers. This study provides the first insight into the morphological and molecular diversity of an obligate cave-dwelling representative of Oribatida. The distribution of COI haplotypes showed clear geographic structuring, with local populations being more closely related to each other than to distant populations. However, the correspondence between geographic and genetic distances among populations was only weakly supported. Populations at the edge of the Western Carpathian distributional range were genetically less diverse than those from the core area, and no interpopulation gene flow was detected. The Moravian Karst harboured the most genetically divergent populations, indicating a separate species. Comparison of 59 morphological traits suggested several karst-specific characters. The large genetic distances between populations, the lack of gene flow and the presence of only minor morphometric differences indicate that K. lengersdorfi is in fact a complex of cryptic species. Divergence time, estimated from the standard mitochondrial mutation rate for Arthropoda, indicated a Late Miocene diversification of the two basal phyletic lineages from an ancestral population. 28S nuclear gene did not comfirm species level of divergent populations. The diversity and distribution of K. lengersdorfi lineages are discussed in light of the geographic location and geological history of the study areas. This study also contributes to the general understanding of subterranean biodiversity, the evolution of cave invertebrate lineages and the biogeographic theory of extra-Mediterranean glacial refugia in Central and Western Europe.