Isonychus fraternus is a species of beetle of the family Scarabaeidae. It is found in Bolivia.
Adults reach a length of about 5.5âÂÂ6 mm. They are brown, while the elytra and sometimes also the abdomen, are black. Both the upper and lower surfaces are densely covered with greenish-yellow scales. The frons is punctured and covered with yellowish setae. The antennae are reddish-brown, with a blackish-brown club. At the end of the elytra, there is usually a small white spot.