Ceratozamia alba (Zamiaceae): A new cycad species from the Selva El Ocote Biosphere Reserve in Chiapas, Mexico

Ceratozamia alba sp. nov., a new cycad species from the Selva El Ocote Biosphere Reserve in northern Chiapas, Mexico, is described and compared to its congeners. Our earlier observations led us to think that these populations belonged to C. robusta, given their geographic location and the general morphological resemblance of adult individuals. However, seedlings and juveniles are more similar to C. santillanii, another geographically proximal species with which it has a sister relationship. We have determined that C. alba is easily distinguishable from other Ceratozamia species by the whitish-green emerging leaves that turn bluish green upon maturation, and the bluish green male and female mature cones. In addition, C. alba possesses several morphometric trait variations that are significantly different from the two geographically proximal species mentioned above, such as leaf number, leaflet number, petiole and rachis length, and median leaflet width. Ceratozamia alba should be considered as a critically endangered species (CR) due to its low population size, ongoing habitat destruction, and extremely narrow distribution range.