Recent efforts to catalogue global biodiversity using genetic techniques have uncovered a number of "cryptic" species within morphologically similar populations that had previously been identified as single species. Chlosyne lacinia (Lepidoptera: Nymphalidae), with a range extending from the Southwest U.S. to South America, is one of the most phenotypically variable and broadly distributed butterfly species in the New World. We sampled populations of C. lacinia in two temperate locations (California and Arizona) and one tropical location (El Salvador) to determine if cryptic species were present at this scale (temperate vs. tropical). We examined mtDNA sequence variation in COI, COII, the intervening tRNA (Leucine-2), 16S, 12S and an additional intervening tRNA (Valine), accounting for approximately 20% of the mitochondrial genome (3479 bp). Among all C. lacinia individuals, sequence divergence did not exceed 0.0084 compared to a 0.06 estimated divergence between C. lacinia and congener C. leanira. We also found subclade structure which did not clearly correspond to geography or subspecific designation. Though the mitochondrial phylogeny suggests a complex evolutionary history and biogeography, we demonstrate that one C. lacinia species is distributed throughout North and Central America spanning a diverse set of temperate and tropical habitats. and Timothy C. Bonebrake, Ward B. Watt, Alejandro Perez, Carol L. Boggs.