DNA BARCODES OF CLOSELY RELATED (BUT MORPHOLOGICALLY AND ECOLOGICALLY DISTINCT) SPECIES OF SKIPPER BUTTERFLIES (HESPERIIDAE) CAN DIFFER BY ONLY ONE TO THREE NUCLEOTIDES

Abstract

Unlike most species of Lepidoptera whose DNA barcodes have been examined, closely related taxa in each of three pairs of hesperiids (Polyctor cleta and P. polyctor, Cobalus virbius and C. fidicula, Neoxeniades luda and N. pluviasilva Burns, new species) seem indistinguishable by their barcodes; but that is when some of the cytochrome c oxidase I (COI) sequences are short and sample sizes are small. These skipper butterflies are unquestionably distinct species, as evidenced by genitalic and facies differences and by ecologic segregation, i.e., one species of each pair in dry forest, the other in adjacent rain forest in Area de Conservación Guanacaste in northwestern Costa Rica. This national park is the source of the specimens used in this study, all of which were reared. Larval foodplants are of no or problematic value in distinguishing these species. Large samples of individuals whose barcodes are acceptably long reveal slight interspecific differentiation (involving just one to three nucleotides) in all three pairs of skippers. Clearly, the chronic practice of various taxonomists of setting arbitrary levels of differentiation for delimiting species is unrealistic.