A REEXAMINATION OF SPECIES BOUNDARIES AND HYPOTHESES OF HYBRIDIZATION CONCERNING SOLANUM-MEGISTACROLOBUM AND S-TORALAPANUM (SOLANUM SECT PETOTA, SERIES MEGISTACROLOBA) - MOLECULAR-DATA

Solanum megistacrolobum and S. toralapanum are two phenetically similar wild potato (Solanum sect. Petota) species, classified in series Megistacroloba, that together are distributed from southern Peru to northwestern Argentina. They have variously been synonymized, recognized as varieties of S. megistacrolobum, or recognized as distinct species. We used 22 single- to low-copy random genomic DNA probes from potato, hybridized to total DNA digested with DraI, EcoRI, EcoRV, and HindIII, to investigate their taxonomic status. We also investigated the hybrid origin of S. raphanifolium and the hybrid origin of S. acaule subsp. aemulans. Our results are concordant with a separate morphological study, showing weak differentiation between S. megistacrolobum and S. toralapanum, but possible only with multivariate methods. These combined morphological and molecular results most closely fit the contemporary treatment of S. megistacrolobum and S. toralapanum at the varietal level. We propose the new combination S. megistacrolobum subsp. toralapanum in order to bring consistency to taxa within sect. Petota, where different authors recognize identical taxa as varieties or subspecies. Our results also show possible hybridization between S. megistacrolobum and S. acaule subsp. aemulans in Argentina, discount the hybridization hypothesis of S. raphanifolium, and show that the species-specific bands of S. albicans relative to S. acaule are shared with many other species in sect. Petota.