Wesmaelius (Kimminsia) nanacamilpa Marquez & Contreras, sp. n., a brown lacewing from Tlaxcala state, Mexico is described and illustrated. This is the second recorded species of Wesmaelius from Mexico, and the third from Middle America. Males of the new species may be identified by parameres separate apically, styliform sclerites directed basally, as well as a rounded gonarcus with a short entoprocessus. Females may be distinguished from closely related species by a subgenital plate with the central plate broadly incised basally. There are now 16 species of Wesmaelius known from the New World.
Keywords: Brown lacewings; Tlaxcala; Transmexican Volcanic Belt; taxonomy.