Endemic Families of Madagascar. XI. A new critically endangered species of Schizolaena (Sarcolaenaceae) from Tapia woodland in south-central Madagascar

Schizolaena isaloensis Rabehevitra & Lowry is described based on material from a small area of highly degraded, seasonally burned Tapia woodland near the southern limit of the Isalo National Park in south-central Madagascar. The species is illustrated and colour photographs are presented of an isolated remnant individual. The species most closely resembles another subhumid forest member of the genus, S. microphylla H.Perrier, from which it differs by several leaf characters, including the size and shape of the blade, the form of the apex, the prominence of the secondary venation on the abaxial surface and the density of its indumentum, and by its smaller flowers with more narrow petals. Schizolaena isaloensis is assigned a preliminary conservation status of Critically Endangered using the IUCN Red List criteria.