A new species, Polycarpaea tanzaniensis (Caryophyllaceae), from Tanzania

Summary Polycarpaea tanzaniensis Borosova, Defty & Rokni, a new species of Caryophyllaceae from Tanzania, is described and illustrated. It is morphologically similar to P. eriantha which is widespread in Africa and P. tenuistyla which is endemic to SE Kenya but differs from both in having a prominent brown midrib on the stipules, bracts and sepals; broad sessile dark brown glands at the base of the bracts and sepals; shorter petals, stamens longer than the petals; a longer style; 5 ovules and three brown stripes on the capsule. It differs in addition from P. eriantha in having longer sepals and a single stigma and from P. tenuistyla in having fewer cauline leaves in each whorl, longer stipules, bifid bracts, a more compact inflorescence, shorter, broadly elliptic petals and an ovoid capsule. Polycarpaea tanzaniensis grows in Brachystegia woodland on sandy and loamy soils. Its extinction risk is provisionally assessed as Least Concern (LC).