A curious new species of Xenostegia (Convolvulaceae) from Central Africa, with remarks on the phylogeny of the genus

The polymorphic genus Merremia Dennst. ex Endl. has been shown to be polyphyletic. In 1980, Xenostegia D.F.Austin & Staples was separated from the first, based on its longitudinally dehiscing anthers, stigmas with long tapering papillae, and non-spiny, pantoporate pollen, and accommodated two species in the Old World tropics. A recent molecular study and subsequent review of the tribe Merremieae resulted in the distinction of seven genera and corroborated the delimitation of Xenostegia at genus level, with three more species added to it. During fieldwork carried out in 2015 and 2016 in the Lomami National Park, Democratic Republic of the Congo, material was collected of a Convolvulaceae species with pinnatifid leaves that was morphologically very close to Xenostegia sapinii, but deviated notably in sepal shape and corolla length. Closer examination revealed additional distinctive characters leading to the conclusion that it represents a distinct taxon new to science. Its pantoporate...