The worker of Aparatermes thornatus is described as the fourth species of a widespread Neotropical termite genus, Aparatermes, from the worker caste. This species occurs in northern Amazonia. The enteric valve armature of A. thornatus and the unique coloration of its worker's head capsule distinguish it from its 3 congeners. Molecular data recovered the proposed new species as a sister to Aparatermes silvestrii. Type material is deposited at Coleccion Entomologica Forestal, Universidad Distrital “Francisco Jose de Caldas” (CEFUDFJC - 45 National Registry of Collections) in Bogota, Colombia, and the University of Florida, Termite Collection (UFTC) at the Fort Lauderdale Research and Education Center, Fort Lauderdale, Florida, USA.