Flicker, Ben , Ballard Jr, Harvey .
Pleuriospermum: a new genus of Violaceae.
Recent molecular evidence has shown the genus Hybanthus Jacq. to be highly polyphyletic. Hybanthus sensu lato has been traditionally diagnosed based on zygomorphic flowers with one petal significantly enlarged relative to the others, a basal sac or short spur, seeds that are unwinged, free stamens, and glands on two stamens enclosed by the basal sac/spur. One of the clades that is well supported as distinct by a suite of morphological traits and chloroplast DNA sequence data will be described as Pleuriospermum. The new genus can be distinguished by its strongly zygomorphic flowers with a short-spurred and much-expanded bottom petal; staminal glands medially attached to the filaments and often elongate; three-valved capsules with (2)3-4 seeds per valve; pale yellow ellipsoidal seeds usually ornamented with longitudinal ribs, foveolae or punctae; and a base chromosome number of x = 8. Pleuriospermum is distributed throughout much of the Old World tropics, with a center of diversity in tropical east Africa. Twelve species (most to be raised from intraspecific status) are currently described in Pleuriospermum, and several additional species await description. Many species are narrow endemics,whereas one widely distributed species, Pleuriospermum enneaspermum comb. nov., is a common roadside weed throughout most of the genus' range. A synopsis of the new genus, including morphological traits,distribution maps, and phylogenetic relationships of species inferred from molecular evidence, will be presented.
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1 - Ohio University, Environmental and Plant Biology, 315 Porter Hall, Athens, OH, 45701, USA
2 - Ohio University, ENVIR & PLANT BIOLOGY-PORTER H, 315 Porter Hall, Athens, OH, 45701-2979, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Franklin A/Hyatt
Date: Monday, July 9th, 2012
Time: 2:00 PM