The Genus Uroleucon Mordvilko (Insecta, Aphidoidea) in South America, with a key and descriptions of four new species

Abstract Uroleucon is one of only two genera of Aphidinae to have undergone significant speciation in South America, with a group of about 14 endemic, morphologically similar species feeding on native Compositae, especially Baccharis. Multivariate morphometrics (canonical variates analysis, CVA) was used to discriminate between these species and compare them with the North American subgenus Lambersius , in which most of them have hitherto been placed. It is concluded that they probably form a separate monophyletic group. Four new species are described in this group — brevisiphon , essigi , petrohuense and pseudomuermosum — and five names are placed in synonymy. Of the other species of Uroleucon in South America, U. lizerianum is widespread and feeds on many species of native and introduced Compositae; it is morphometrically inseparable from the North American species U. ambrosiae and is probably an introduced form of that species, but has consistently fewer secondary rhinaria. A key is provided to the 19 available species of Uroleucon recorded from South America.