About a peculiar form of Senegalese Polycarpon (Caryophyllaceae) and a diagnostic key to the African taxa in the genus

As part of an ongoing investigation into the genus Polycarpon, the name P. prostratum var. littorale, described from Senegal in 1967 by J. Raynal and A. Raynal, was studied. It does not appear in World Flora Online (WFO), is unplaced in Plant Of the World Online (POWO) and in the International Plant Names Index (IPNI). Furthermore, no study appears to be published after that by J. Raynal and A. Raynal. With the aim to clarify the identity and taxonomic status of Raynal & Raynal’s variety, a detailed study of the type and other specimens is here presented. The name is lectotypified on a specimen preserved at P (barcode P00388964) and further two isolectotypes were traced (P00388965 and P00388966). Based on the morphology of Raynal & Raynal’s taxon and the current circumscription of the genus Polycarpon as monophyletic (with P. tetraphyullum) a nomenclatural change (P. tetraphyllum subps. littorale comb. et stat. nov.) is proposed. The subspecies is assessed as Endangered based on the IUCN criterion B2. Furthermore, a diagnostic key to the Polycarpon taxa occurring in Africa is presented.