Ptilodactylid beetles. Only two aquatic/semiaquatic genera in the Western US (Anchycteis and Araeopidius); also many strictly terrestrial taxa. Adults are terrestrial and found in riparian vegetation. Body elongate, up to 16 mm; antennae 11-segmented and filiform, serrate or pectinate (segments with long, lateral extensions); pronotum rounded anteriorly, crenulate posteriorly; 5 visible abdominal sternites, the 5th emarginate.

Larvae of Anchycteis and Araeopidius are aquatic to semiaquatic, usually found in wetted mosses or moist leaf packs in spring seeps or small, headwater streams. Larvae elongate, subcylindrical; no abdominal gills; abdomen with 9 distinct segments; with or without small urogomphi; operculum absent; hooks present along with anal lobes.