Systematics and taxonomy of the Solanum carolinense clade (Solanaceae)

WAHLERT, G.A.; CHIARINI, F.; BOHS, L.

Columbus

Congreso; Botany 2012 - The Next Generation (Annual Meeting of the American Society of Plant Taxonomists); 2012

American Society of Plant Taxonomists

Molecular phylogenetic studies in the giant genus Solanum have confirmed phylogenetic relationships in Solanum subgenus Leptostemonum, the largest infrageneric group in the genus, with 350-450 species. Among the 14 subclades identified in subgenusLeptostemonum is the Solanum carolinense clade, composed of ca. 5-8 species disjunctly distributed in North America and the subarid and seasonally dry tropical regions of South America. The goal of this project is to produce an authoritative systematic treatment of the species in the S. carolinense clade using both herbarium and field studies and molecular phylogenetic approaches. Most species in the group have a weedy, invasive habit, often growing in disturbed areas, whereas S.pumilum is a recently rediscovered, narrow endemic from dolomite outcrops in Alabama, USA. The South American species have been preliminarily treated taxonomically, yet species boundaries remain problematic for some taxa. Ongoing systematic studies seek to characterize morphological synapomorphies that will not only delimit species within the group, but also differentiate the S. carolinense clade from other clades in S.subgenus Leptostemonum.Interspecific hybridization (S. aridum X S. juvenale) and tetraploidy (S. dimidiatum, S. juvenale, S. comptum) have been documented in the S. carolinense clade, processes that have contributed to problematic species circumscriptions and phylogenetic inference. We present results of molecular phylogenetic studies that delimit the S. carolinense clade, reconstruct relationships among its species, and clarify the clade's position within S. subgenus Leptostemonum. These results also shed light on species limits,morphological evolution, and biogeographic patterns within the S.carolinense clade.