The scarab genus Cnemida includes eight species (including C. gigantea Jameson n. sp. from Colombia and C. tristriata Jameson n. sp. from Surinam) that inhabit tropical moist and premontane forests of South America, Central America, and Mexico. Keys to adults, diagnostic characters, descriptions, and distributions are presented. The larva of C. intermedia Bates is described and integrated into a key to larvae of the tribe Rutelini. A cladistic analysis among the species of Cnemida is based on 35 morphological characters and uses members of the genera Pelidnota and Rutela as outgroups. Four equally parsimonious cladograms are discussed.