Investigation of the Phylogenetic Relationships Among Subspecies of Cercyonis Pegala (Nymphalidae: Satyrinae)

Abstract

The common wood-nymph, Cercyonis pegala, is a North American butterfly found throughout the United States, northern Mexico, and southern Canada. Cercyonis pegala agawamensis is a recently described subspecies that is differentiated from other subspecies of C. pegala based on habitat, behavior, and phenotype. A major defining characteristic is habitat, with C. pegala agawamensis found in salt marsh habitat, C. pegala maritima in coastal upland habitat, and C. pegala nephele in a northeastern upland habitat. The level of genetic differentiation between the subspecies is unknown; therefore, we investigated the phylogenetic relationships among C. pegala agawamensis, C. pegala nephele, and C. pegala maritime using the mitochondrial cytochrome c oxidase I (COI) gene. COI is a 648 base-pair region that is used as a barcoding standard to help identify the relationships between species and subspecies. Eight mtDNA haplotypes were found among 31 samples of the three subspecies. The data show that C. pegala nephele is genetically different from C. pegala agawamensis and C. pegala maritima. However, there is no genetic differentiation between C. pegala maritima and C. pegala agawamensis. Small phenotypic differences used to identify samples sometimes placed subspecies in atypical habitats (for example, C. pegala maritima in salt marsh habitat). Therefore, there does not appear to be a genetic, morphological or habitat basis to justify separate subspecies status for C. pegala agawamensis.