REEXAMINATION OF SERIES RELATIONSHIPS OF SOUTH-AMERICAN WILD POTATOES(SOLANACEAE, SOLANUM SECT PETOTA) - EVIDENCE FROM CHLOROPLAST DNA RESTRICTION SITE VARIATION

Chloroplast DNA (cpDNA) restriction enzyme site analysis was used to t est hypotheses of series and superseries affiliations of 76 taxa, repr esenting 11 of the 13 South American series (material unavailable for two series) of wild potatoes (Solanum sect. Petota) recognized in the latest classification by Hawkes. The cladistic results, combined with those from earlier cpDNA studies of 30 taxa of the Mexican and Central American species (representing eight series; ser. Conicibaccata and s er. Tuberosa have representatives in Mexico and in South America), sup port four main clades for 17 of the 19 series examined in sect. Petota : (1) the Mexican and Central American diploid species, exclusive of S . bulbocastanum, S. cardiophyllum, and S. verrucosum, (2) S. bulbocast anum and S. cardiophyllum (ser. Bulbocastana, ser. Pinnatisecta), (3) South American diploid species constituting all of ser. Piurana, but a lso members of ser. Conicibaccata, ser. Megistacroloba, ser. Tuberosa, and ser. Yungasensia, (4) all Mexican and Central American polyploid species (ser. Longipedicellata, ser. Demissa), S. verrucosum (diploid Mexican species in ser. Tuberosa), and South American diploid and poly ploid members of ser. Acaulia, ser. Circaeifolia, ser. Commersoniana, ser. Conicibaccata, ser. Cuneoalata, ser. Lignicaulia, ser. Maglia, se r. Megistacroloba, ser. Tuberosa, and ser. Yungasensia. Each of these clades contains morphologically and reproductively very diverse specie s, and there are no evident morphological features that unite members within a clade to therefore distinguish them. These results strongly s uggest a need for a reevaluation of the series and superseries classif ications of sect. Petota.