Pleotrichophorus acanthovillus (Knowlton & Smith 1936) = Pleotrichophorus utensis (Pack & Knowlton 1929)

P. acanthovillus has been distinguished from P. utensis occurring on the same hosts ( Chrysothamnus viscidiflorus and Gutierrezia spp.) in western USA solely on the basis of differences in shape of dorsal hairs in apterae, and in particular the subapical caudal hair(s), which are said to be pointed in apterae of acanthovillus, and flattened apically in utensis (Corpuz­Raros & Cook 1974) . This character is unreliable as it is related to the degree of alatiformity, alatae having longer and less expanded hairs than apterae.