Single-specimen
Guides
Acneus beeri
Beer's false water penny beetle
Acneus beeri is a species of aquatic beetle in the family Psephenidae, known from a single female specimen collected east of Cascadia, Oregon in July 1940. The species belongs to the false water penny beetles, a group characterized by their flattened, oval body form adapted for clinging to submerged surfaces in flowing water. No additional specimens have been reported in the more than 80 years since its original description, making it one of the most poorly known North American beetle species.