Species limits of Solanum berthaultii Hawkes and S-tarijense Hawkes and the implications for species boundaries in Solanum sect.: Petota

Solanum berthaultii and S. tarijense are two wild potato (sect. Petota) species distributed from Bolivia to northern Argentina. All authors have accepted them as good species since their publication in 1944, but they have been hypothesized to hybridize extensively with each other and with other species, despite their classification into different series and superseries by some authors. This study is a molecular counterpart (AFLPs, plastid DNA restriction site data, survey of a plastid DNA deletion) to a prior morphological study of these two species. AFLP data show weak support for separate species status for some accessions, but with many exceptions. In agreement with the morphological results we place S. tarijense into synonymy of S. berthaultii, and use herbarium specimen data for a taxonomic treatment to include a description, synonymy, and mapping of all accessions. We show similar taxonomic problems in sect. Pelota and suggest that there will be a continuing trend of reduction of names in wild potatoes.