A new microendemic species of Hunzikeria (Petunieae, Solanaceae) from the gypsum outcrops of southern Jalisco, Mexico

Abstract

Hunzikeria is a petunioid genus of Solanaceae that includes three species. The genus presents a disjunct distribution between South and North America. Hunzikeria coulteri and H. texana occur in North America, while H. steyermarkiana is reported from Venezuela. During botanical explorations in western Mexico, we found a population of Hunzikeria that differed from the three known species. Believing that we had found an undescribed species, we collected samples and prepared herbarium vouchers. We compared our material with morphological descriptions and herbarium specimens of the other species in the genus. Our results indicate that we discovered a new species, named here as Hunzikeria gypsophila. This new species is a microendemic gypsophyte that inhabits two gypsum ravines in southern Jalisco, Mexico. Hunzikeria gypsophila differs from the other three species in being a subshrub of taller stature and having petiolate leaves, wider leaf blades, longer corolla tubes, and broader corolla limbs. The most morphologically similar species is H. steyermarkiana, which differs in having anthers of equal size, while all the North American species have didynamous anthers. Hunzikeria shows a clear affinity for sedimentary soils and H. gypsophila is the first species recorded on gypsum. The gypsum outcrops of western Mexico have a unique flora, which likely became isolated due to volcanic activity. With this new find, Hunzikeria comprises four species. We provide a key for their identification and a distribution map for Mexico.