Trichinopus polygonus is a species of beetle of the family Scarabaeidae. It is found in Namibia.
Adults reach a length of about 5.5 mm for males and 6.5 mm for females. The head, pronotum, underside and pygidium are brownish-black, while the elytra are yellowish-brown, with the lateral margins and sutural striae brown. The legs and antennae are also brown. The underside is covered with long, dense, light-colored hairs and the legs have particularly long brown hairs. The lateral margins of the pronotum and elytra are fringed with long, light-coloured hairs. On the disc and anterior margin of the pronotum, as well as on the head, there are only a few long, light-coloured hairs.