Niphargus entlebuchensis sp. nov., a new subterranean amphipod species (Crustacea, Amphipoda, Niphargidae) restricted to a karst area in Central Switzerland

Groundwater ecosystems are of high interest to both taxonomists and ecologists for their high diversity as well as pronounced biogeographic patterns of occupying organisms persisting across major geological time periods, such as glaciation cycles. Over the last years, coordinated efforts increased the knowledge on the diversity and distribution of stygofauna in Switzerland, particularly the order Amphipoda, revealing several new species with highly localized occurrences. Thereby, citizen science approaches and collaborations with both cavers and drinking water providers have greatly increased the available data. As a result of these activities, we here describe another new species of the genus Niphargus Schiödte, 1849, namely Niphargus entlebuchensis sp. nov . Molecular and morphological species delimitation analyses both clearly support its species status. Multi-marker phylogenetic analyses recover the new species within a clade that comprises several other Swiss species, such as N. luchoffmanni Fišer et al., 2018 and N. muotae Fišer et al., 2017, while the internal structure of the clade received weak support. So far, the species has only been found in a single karst mountain ridge in Central Switzerland, suggesting that it is a narrow-range endemic.