New insights into the distribution, ecology, and systematic position of the rare water mite Rutripalpus limicola Sokolow, 1934 (Acari: Rutripalpidae)

The water mite Rutripalpus limicola Sokolow, 1934, can be considered exceptionally rare. It shows a scattered distribution range and, until recently, was known from six sites across Europe only. This strictly spring-dwelling species has a highly localised distribution, presumably due to its specific ecological requirements. We present the first records of R. limicola in the Netherlands and review the current state of knowledge on its distribution and biology. In addition to the previously existing morphology-based investigations, we provide a phylogenetic placement based on 28S rRNA gene data and shed light on the controversial systematic position of R. limicola: In contrast to the previously hypothesised Lebertioidea-relatedness of the isolated, monotypic family Rutripalpidae, our results reveal a putative Hydryphantoidea association. Moreover, we discuss the host-parasite association of R. limicola larvae and the dipteran family Ptychopteridae. Combined with additional information derived from the new records from the Netherlands, we contribute to a better understanding of this elusive species' biology and phylogenetic position.