P. 323-331Ucrimyzus villalobosi Mier Durante & Pérez Hidalgo gen. n., sp. n. (Hemiptera: Aphididae:
Macrosiphini) are described from apterous and alate viviparous females collected on species
of genera Bidens, Schkuhria, Senecio and Stevia (Asteraceae: Asteroideae) in Costa Rica
and Mexico. Principal components analysis (PCA) was done to verify that the studied aphids
belong to a single species regardless of their geographical origin or host plant. Molecular
analyses were carried out on the sequences of a fragment of the mitochondrial gene encoding
for cytochrome c oxidase subunit 1 (COI) and of a fragment of the nuclear gene encoding
elongation factor 1α (EF1α). The taxonomic discussion takes into account the conclusions
of the molecular analyses and the morphologic study compared with other genera of Macrosiphini.
The identification keys by Blackman & Eastop (2006) to aphids living on each
mentioned plant genus are modified to include the new speciesS
