Species delimitation and recognition in the Pediomelum megalanthum complex (Fabaceae) via multivariate morphometrics

Abstract

Pediomelum is a genus endemic to North America comprising about 26 species, including the megalanthum complex, which consists of P. megalanthum and its varieties retrorsum and megalanthum, P. mephiticum, and the recently described P. verdiense and P. pauperitense. Historically, species of the megalanthum complex have been variably recognized at the species or variety levels, dependent upon the relative importance of morphological characters as diagnostic of species. Ten quantitative morphological characters regarded as diagnostic at the species level were analyzed using multivariate morphometrics across these taxa in order to examine the discriminatory power of these characters to delineate species and to aid in species delimitation. The analyses support the recognition of P. megalanthum, P. mephiticum, and P. verdiense at the species level, P. retrorsum as a variety under P. megalanthum, and suggest the sinking of P. pauperitense into P. verdiense. The findings of the present study help quantify the power of certain characters at delimiting taxa and provide a basis for taxonomic revision of the P. megalanthum complex.