Pollen and morphometric analysis reveal Solanum tavinuuyuku (Solanaceae), a new dioecious species from Mesoamerican Solanum sect. Anarrhichomenum

<i>Solanumtavinuuyuku</i>, of the Sierra Madre del Sur ecoregion of South-Central Mexico, is a viny, node-rooting species of the Potato clade, in the subclade Solanumsect.Anarrhichomenum. <i>Solanumtavinuuyuku</i> is distinguished from its relatives by possessing long and narrow, lanceolate, ovate to falcate, 1-3-foliate leaves with (5-)7-10 secondary veins; large, persistent pseudo-stipules found at nearly every node on herbarium material; and white, violet-tinged corollas particularly pronounced in the floral bud. <i>Solanumtavinuuyuku</i> is functionally dioecious, producing functional, tricolporate pollen and non-functional, inaperturate pollen in short and long-styled flowers, respectively, joining its close relative <i>S.appendiculatum</i> as one of only two documented dioecious species in the entire Potato clade. Separation of <i>S.tavinuuyuku</i> from its closest ally, the simple-leaved <i>S.ionidium</i>, is based on morphometric and geographic evidence presented here.