Are genera arbitrary?

Generic classifications of Hemiptera-Auchenorrhyncha, primarily nearctic leafhoppers (Cicadellidae), were analysed for congruence to genetic "barcode" data obtained from more than 3000 specimens representing 1,234 species in 236 taxa previously considered to be genera. Barcode analysis recovered 51 genera that were previously based only on overall similarities, and another 98 genera with "unique" synapomorphies; 38 taxa were confirmed to be subgenera, and 30 others should become subgenera within larger genera; only 8 represented monobasic genera and 11 require more information from other biogeographic regions. This technique supports existing taxonomy, corrects errors and removes the bias of individual expert judgments.