Macronychus quadrituberculatus Mueller, 1806
Family: Elmidae
Size: 3.0 mm (2.8 to 3.3 mm)
Distribution: Europe
Ecology: Lives on  submerged wood in river rapids
Location: Germany, Upper Bavaria, Muenchen, Ampermoching, Amper river
leg. A.Skale, 28.VIII.2001; U.Schmidt, 2001
Photo: U.Schmidt, 2015

Macronychus quadrituberculatus   (Flickr)