A reassessment of the Ceratozamia miqueliana species complex (Zamiaceae) of southeastern Mexico, with comments on species relationships

The Ceratozamia miqueliana species complex has been revised from a morphological, anatomical and biogeographical perspective. The complex consists of five closely related species, one of which is new, C. santillanii sp. nov., and is described and illustrated from the northern highlands of Chiapas. The five species, although not sympatric, occur in the 'Arc' Pleistocene floristic refuge that covers southern Mexico, including northern Oaxaca and Chiapas, as well as southern Tabasco and Veracruz. The five species are characterised by oblong, oblanceolate to widely oblanceolate leaflets with decumbent or erect megastrobili when ripe. The species complex consists of C. becerrae Perez-Farr., Vovides & Schutzman C. euryphyllidia Vazq.Torres, Sabato & D.W. Stev., C. miqueliana H. Wendl., C. zoquorum Perez-Farr., Vovides & Iglesias and the new species which is related to C zoquorum, but differs from these in leaf, male and female cone growth habit, as well as inter-leaflet distance. Discriminant analysis using the five species with 14 variables showed significant differences (Wilks lambda test, P < 0.01) for four functions among the five species. Mahalanobis distances were also highly significant among the five species (P < 0.01). Ceratozamia euryphyllidia and C. becerrae were the most distant, whereas C zoquorum and C. becerrae were closest.