Phylogenetic analyses of a new freshwater amphipod reveal polyphyly within the Holarctic family Crangonyctidae, with revision of the genus Synurella

Abstract

Abstract A new genus and species of crangonyctid amphipod, Sicifera cahawba gen. & sp. nov., is described from Dallas County, AL, USA, based on both morphological and molecular comparison with similar crangonyctids. These data, with the application of four species delimitation models, identify the taxon as distinct when compared with related species. Nearctic members of the crangonyctid genus Synurella form a separate, well-supported monophyletic lineage when compared with Palaearctic members, which differ considerably in both molecular and morphological markers. Nearctic members, with the exception of the enigmatic Synurella (Eosynurella) johanseni, are placed in the newly erected Sicifera. The separation of these two genera implies that Palaearctic and Nearctic crangonyctid lineages might not be as closely related as once thought, and their evolutionary and biogeographical history requires further review. In addition, a key to Nearctic members of the genera Eosynurella/Sicifera is presented to aid in future identification.