Format: ORAL

Eric J. Tepe1, Jacob Bryant1

1 Department of Biological Sciences, University of Cincinnati, Cincinnati, USA

Solanum sections Herpystichum and Pteroidea are small sections of ten species each within the Potato Clade of the enormous genus Solanum. Both sections range from Central America to the central Andes and are heterogeneous groups of species that include herbs and vines, and species with simple and compound leaves. Pteroidea is defined by inflorescences in an axillary position, unifoliate sympodial units, and rugose, conical fruits in most species. This combination of characters is unique in Solanum and lends support to the monophyly of Pteroidea. Herpystichum, on the other hand, is more heterogeneous, but can be characterized by onion-shaped floral buds and distinctly flattened fruits in some species. Phylogenetic analyses based on nuclear and plastid markers have shown that the two sections form a strongly supported clade, but an understanding of the relationship between the sections has remained elusive. Analysis of concatenated data supports the two sections as reciprocally monophyletic, or with Pteroidea nested within Herpystichum. Similarly, analysis of individual markers recovers Pteroidea as sister, in a polytomy with, or nested within Herpystichum. Our analyses of both nuclear and plastid markers, as well as nearly complete plastid sequence data suggest frequent shifts in leaf complexity in the entire clade and a single origin of sect. Pteroidea. Origins of the flattened fruits of Herpystichum, as well as the monophyly of the section itself, remain enigmatic. The additional data, however, reinforce the previous findings that the widespread species, S. anceps and S. mite are not monophyletic, and both morphology and molecular data suggest that there is at least one undescribed species in sect. Pteroidea. Additional sequence data using ddRAD-seq is underway, which may provide additional insights into the evolution and relationships among these groups.