Ceratozamia schiblii (Zamiaceae): A New Cycad Species from the Eastern Mountains of Oaxaca, Mexico

Ceratozamia schiblii (Zamiaceae), a new species endemic to the highlands of eastern Oaxaca, Mexico, is described. The new species is part of the C. robusta species complex, which is a group of closely related species with very similar morphology. Among them, the new species can be distinguished by its brown leaflets in emerging leaves, a very long peduncle in seed cones, and the green color of mature pollen cones. Compared with the other species in the C. robusta species complex, C. schiblii has one of the longest rachides, and the highest number of leaflet pairs. The recognition of C. schiblii apparently resolves the total number of species within the C. robusta species complex. The region where C. schiblii populations occur coincides with the Neogene refugia areas of the Neotropical flora, which adds evidence to the importance of the mountain systems from Oaxaca and Chiapas, Mexico, in the diversification history of cycads.