Knobel's Riffle Beetle (Stenelmis knobeli), a State Endangered species, is a black or gray cylindrical beetle often encrusted with sand or mineral deposits. It has a sculptured pronotum, light markings on elytra, and filiform antennae. The adult measures 2.53-3.10mm from anterior pronotum to tips of the elytra. Narrow, elongate elytra and weak sculpturing of the pronotum separates this species from the other 13 Stenelmis species in the state with similar elytral markings. It has been found where the in large warm rivers with a shifting sand bottom. Adults have been found under or low on the sides of large sandstone rocks in riffles and runs. The species does best in habitat with constant water flow, little sediment, and moderate oxygen levels.
