Phylogenetic analysis of the Niphargus orcinus species–aggregate (Crustacea: Amphipoda: Niphargidae) with description of new taxa

Abstract

The Niphargus orcinus aggregate, also “subgenus Orniphargus” of the genus Niphargus, is a widely distributed assemblage of large‐bodied amphipods. Although it comprises the most prominent European groundwater animals, its phylogeny has not yet been scrutinized and its monophyly has never been tested. In this study, 30 putative “Orniphargus” taxa and 14 other Niphargus and outgroup species were examined cladistically using a matrix of 71 morphological characters. The strict consensus tree constructed of 34 equally parsimonious trees demonstrated that “Orniphargus” does not constitute a monophylum. Most of the species were divided into two large clades. Both clades contain species from the western Balkans (mainly the Dinaric Karst) with partly overlapping ranges. Niphargus croaticus pachytelson and N. orcinus redenseki are elevated to species rank. Four new species are described: N. dolichopus sp. n., N. polymorphus sp. n., N. dabarensis sp. n. (all Bosnia and Herzegovina) and N. lourensis sp. n. (Greece).