The arachnid order Uropygi has never been subjected to phylogenetic research. We perform the first systematic revision and molecular phylogenetic analysis of Uropygi, focusing on the Brazilian genera Thelyphonellus and Mastigoproctus. Our study indicates that Mastigoproctus actually comprises two different genera: the revalidated genus Amauromastigon with a single species, and a new genus Heptatarsus with two species, increasing the number of Brazilian uropygid genera to three. Additionally, we identify ontogenetically variable morphological characters and caution their use in uropygid systematics. (Image credit: Daniel Castro-Pereira.)