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

Solanum megistacrolobum and S. toralapanum are two phenetically simila r wild potato (Solanum sect. Petota) species, classified in series Meg istacroloba, that together are distributed from southern Peru to north western Argentina. They have variously been synonymized, recognized as varieties of S. megistacrolobum, or recognized as distinct species. W e used 22 single- to low-copy random genomic DNA probes from potato, h ybridized 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 stu dy, showing weak differentiation between S. megistacrolobum and S. tor alapanum, 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 lev el. We propose the new combination S. megistacrolobum subsp. toralapan um in order to bring consistency to taxa within sect. Petota, where di fferent authors recognize identical taxa as varieties or subspecies. O ur results also show possible hybridization between S. megistacrolobum and S. acaule subsp. aemulans in Argentina, discount the hybridizatio n hypothesis of S. raphanifolium, and show that the species-specific b ands of S. albicans relative to S. acaule are shared with many other s pecies in sect. Petota.