Sansevieria bangalalana sp. nov. (Asparagales, Asparagaceae), close to extinction in the wild, and five other narrowly endemic and threatened species of Sansevieria from Tanzania previously unknown to science

Six new species of Sansevieria are described from several regions of Tanzania, a country believed to harbour the highest diversity of Sansevieria species globally. Among these, Sansevieria bangalalana sp. nov. and S. chlorantha sp. nov. occur in the North Pare Mountains region in northeastern Tanzania. Our data indicates that both species are close to extinction now. They have only been found in two and one location, respectively. Sansevieria bangalalana has a unique combination of flower and leaf features that sets it apart from all other species in the genus. Sansevieria embere sp. nov. is solely occurring in a pocket of succulent vegetation within the city limits of Arusha, where our data indicates that it is critically endangered, too. This species and S. chlorantha have unbranched elongate inflorescences (subgenus Sansevieria), while S. bangalalana and the other three species have capitate inflorescences (subgenus Capitulatus). Of the latter, S. muhaensis sp. nov. was found in a restricted area close to the city limits of Kigoma in W Tanzania, where it is critically endangered as well according to our data. Sansevieria rukwana sp. nov. and S. sumbawangana sp. nov. occur in the wider Lake Rukwa Region of SW Tanzania. Their threat status is EN according to our data. The factors most threatening these plants altogether are construction works of roads and houses, and agricultural expansion.