A new species of <i>Hyalella</i> Smith, 1874 (Amphipoda: Hyalellidae) from a unique thermal-spring habitat

Abstract A new species of epigean hyalellid amphipod, Hyalella tiburtiniphila n. sp., is described from a thermal spring in Nye County, Nevada, USA using both morphological and molecular methods. The species displays unique morphological characteristics such as the presence of four dorsoposterior carinae and robust setae on the third uropod and telson, characters which in combination clearly distinguish it from all other described Neartic species of Hyalella. At its type locality, Hot Creek Spring, the species occupies a unique habitat, only being collected from crevices of calcium carbonate in travertine deposits along the spring run. Its absence from other habitats within the spring run suggests it may be adapted to occupy these small, unique habitats, likely due to the pressures of fish predators. Our description of H. tiburtiniphila n. sp. brings the number of described Nearctic species of Hyalella to 20, including three from Nevada.