MORPHOLOGICAL VARIATION OF CORYPHANTHA (CACTACEAE): A MULTIVARIATE APPROACH

Coryphantha consists of 43 to 67 species. This genus exhibit patterns of morphological variations that have been understood differently and have led to an unstable taxonomy, resulting in the fact that a consensus on the delimitation of species has yet to be reached. Previous classifications are based on qualitative characters. In order to clarify and circumscribe species of Coryphantha, different multivariate analysis techniques were used. A total of 1840 individuals among 48 taxa were examined; 467 in the field and 1373 from herbarium specimens. We used 28 vegetative and reproductive characters of which 17 were quantitative and 11 qualitative. Cluster analysis indicated the presence of two major groups based on the presence or absence of extrafloral glands. Discriminant analysis for each subgroup consisting of the cluster analysis allowed circumscription based on morphometric variables of the majority of the analyzed species. Based on morphological characters and multivariate analysis, recognition of taxonomic categories at species or subspecies level is discussed. 45 species and three subspecies are recognized.