Morphological characterization and phylogenetic distance among several genotypes of Rebutia, Aylostera, Mediolobivia and Sulcorebutia (Cactaceae)

摘要

Four genera and 75 species belonging to?Cactaceae?family were investigated regarding their morphology and their molecular polymorphism. The botanical classification that described the phenotypic aspects of different characters, such as number of spines/areoles, length of spines and flower diameter, was used to describe the main peculiarities (morphological method). In?Rebutia?genus, the floral diameter varied between small limits: 2 cm (R. xanthocarpa?v. splendens,?and?R. brachyantha)?to 4.5 cm in?R. calliantha?and?R. marsoneri?(the greatest floral diameter from all the studied species). Of the studied species of?Aylostera?genus,A. fiebrigii?has the greatest length of the spines and?A. narvaecensis?the smallest one. The analysis of the plants morphology showed a relatively low variability of biological material, according to genus and species. The genetic diversity was calculated with Nei and Li’s index, and the phylogenetic tree (dendrogram) was generated with a neighbor-joining program. The dendrogram indicates the diversity of the genotypes, which are grouped into three distinctive large groups. The largest group includes species from the?Mediolobivia?and?Rebutia?genera, which clearly share a common ancestor; the group shares a common ancestor with B and C as well; A includes some but all not descendents. Species from?Rebutia?genus were present in all the described groups. The genetic distance between species fromRebutia,?Mediolobivia, Aylostera?and?Sulcorebutia?genera is small and the differences between the main characters was also quite small, so the trend of combining these species in one genus is justified.