|Reuss, SJ; Meve, U; Mangelsdorff, RD; Liede-Schumann, S: Transfer of Cuban Marsdenia to Ruehssia (Apocynaceae–Asclepiadoideae), and two new species in Ruehssia, Willdenowia, 50 (2020), doi:https://doi.org/10.3372/wi.50.50104 [Link]|
The cosmopolitan genus Marsdenia R. Br. in its conventional circumscription has been shown to be strongly polyphyletic, with all New World species grouping in a single clade. Therefore, the genus Ruehssia H. Karst. was recently reinstated to encompass the 42 Brazilian species, initially. In the present study, the nine Cuban species currently classified under Marsdenia are transferred to Ruehssia, and two species, R. lindenii and R. yamanigueyensis, both endemic to Cuba, are described as new. Ruehssia yamanigueyensis is characterized by very thin, wiry stems and small leaves and flowers, while R. lindenii is like R. clausa in habit, but differs strongly in the shape of the staminal corona. Illustrations and a distribution map for two new species are provided, as well as a key to all Ruehssia species on Cuba. Lectotypification is performed where necessary.