Human population density (2010 U.S. Census from the U.S. Census Bureau) by county with ranges for the eight Bactrurus species. For Bactrurus brachycaudus, B. hubrichti, and B. mucronatus, the range boundary has been interpreted as in Fig. 5.

  Part of: Taylor SJ, Niemiller ML (2016) Biogeography and conservation assessment of Bactrurus groundwater amphipods (Crangonyctidae) in the central and eastern United States. Subterranean Biology 17: 1-29.