Quatre nouvelles espèces de Grewia (Malvaceae, Grewioideae) du sud-ouest de Madagascar

Four new species of Grewia L. (Malvaceae, Grewioideae) from southwest Madagascar are described and illustrated here. They all belong to section Grewia, subgenus Grewia. In the 1970s, three of these species were already annotated as new to science by René Capuron and then David Mabberley described them in the 2000s but they were never validly published. A fourth species is now recognized and it is also formally described in this article: G. rufoarenosa Ramon & Phillipson. This new species is known only from a small area north of the town of Toliara on the red sands of the Ranobe (PK 32 Protected Area). It is characterized by pink flowers that turn bluish as they fade, and has a particularly low number of stamens compared to other species, rhombic leaf blades with crenate to broadly-toothed margins and large, glabrous, four-lobed fruits. The descriptions of the new species are accompanied by a preliminary assessment of their status according to the IUCN Red List Categories and Criteria. Received: 19 February 2025; Accepted: 5 February 2026; First published online: 17 June 2026