PHYLOGENETIC-RELATIONSHIPS OF WILD POTATOES, SOLANUM SERIES CONICIBACCATA (SECT. PETOTA)

Solanum sect. Petota series Conicibaccata is a group of 40 wild potato species, composed of diploids, tetraploids, and hexaploids, distribut ed from central Mexico to central Bolivia. This study examined their s pecies boundaries and interrelationships by phenetic analyses of morph ological data and cladistic analyses of chloroplast DNA restriction si te data. Mitotic chromosome counts were obtained for 114 accessions; s pecies whose first counts are reported here are S. garcia-barrigae, S. orocense, and S. sucubunense. Most results were concordant in showing three main groups of species: 1) tetraploids and hexaploids from cent ral Mexico to southern Ecuador; 2) diploids from northern Peru to Boli via, included in a cpDNA clade of diploids and hexaploids assigned to ser. Demissa and ser. Tuberosa, and 3) diploids and tetraploids from s outhern Colombia to Peru, cladistically related to members of ser. Piu rana. Some species boundaries, and even series boundaries of ser. Coni cibaccata and ser. Piurana, are supported morphologically only by a co mbination of widely overlapping character states, none of which is con stant for a species. Other species have no support, and it is Likely t hat too many species are recognized in the group. The cladistic analys is of chloroplast DNA data suggested that some species represent a com bination of apospecies and plesiospecies, and some populations are of possible hybrid origin.