An updated distribution for the endemic, predaceons diving beetle, Heterosternuta sulphuria, consists of four new locations in the Ozark and Boston Mountain ecoregions of Arkansas. To date, a total of 32 specimens have been collected from these locations that are primarily spring-water influenced, small, shaded aquatic systems. Two populations are recorded for currently protected areas; Hobbs State Park-Conservation Area and Sherfield Cave (effluent stream). The addition of H. sulphuria to the biota list from Sherfield Cave further highlights conservation efforts focused on this unique cave and stream system. The habitat, from which H. sulphuria has been collected includes stream margins within sediment-free gravel and cobble substrate, under leaf material covering bedrock, and within small, shallow depressions and crevices in bedrock. From current surveys, H. sulphuria lias been the brightly colored member of the Hydroporinae collected from these permanent aquatic habitats and co-occurs only with the genera Sanfilippodyles and Hydrocolus.