Rediscovery of Riella alatospora (Riellaceae,Sphaerocarpales), an aquatic,South African endemic liverwort previously known from a now largely transformed type locality

Riella alatospora is reported from cultured sediments from a salt pan near Springfield (Western Cape), South Africa. This species was previously known only from the type locality near Cape Town, and has not been collected since 1932. Because the original locality has been severely affected by urbanization in the past decades, the species is unlikely to survive there. The identity of the specimens obtained from the cultured sediments were confirmed by comparison with the type material of R. alatospora. A detailed description of R. alatospora including lectotypification, illustrations, light and scanning electron microscopy micrographs of spores, and an updated distribution map is presented. Our finding suggests that the genus Riella is likely to be more widespread in South Africa than previously thought and that extensive sampling is required before an accurate distribution of the species can be ascertained. This study also highlights the value of culture sediments in revealing the presence of Riella.