Qualitative and quantitative morphological evidence for recognition of a new species within Ceratozamia (Zamiaceae) from Mexico

Abstract

Several Ceratozamia populations from the “Carso Huasteco” region in Mexico have a controversial circumscription and have been historically identified as Ceratozamia fuscoviridis. In this paper, we present a review of the taxonomic history of this species and provide taxa circumscriptions based on analyses of herbarium specimens from this region and supplemented with fieldwork. For this, we have studied qualitative and quantitative morphological variation at population level. We recognize two species in this group: C. fuscoviridis and a new species, C. chamberlainii. Here, we provide two lines of qualitative and quantitative morphological evidence showing that plants of C. chamberlainii from southern San Luis Potosí to northern Hidalgo are distinct from C. fuscoviridis of central Hidalgo east of Veracruz. These species can be identified by leaflet form, leaf emergence color, color of the ovulate strobilus, and form of the megasporophyll, along with a combination of quantitative morphological characters.