|Meve, U; Liede-Schumann, S: Taxonomic dissolution of Sarcostemma (Apocynaceae: Asclepiadoideae), Kew Bulletin, 67, 751-759 (2012)|
Since molecular analyses have demonstrated that Sarcostemma R. Br. is deeply nested in the predominantly Madagascan stem-succulent clade of Cynanchum L., the genus has been treated as a synonym of Cynanchum. Some of the former Sarcostemma species have been transferred to Cynanchum in the course of various Flora treatments, and some new species belonging to this radiation have been described under Cynanchum. The present contribution serves to complete the formal transfer of Sarcostemma taxa to Cynanchum, in which a total of nine species are concerned: Cynanchum arabicum, C. areysianum, C. brevipedicellatum, C. daltonii, C. forskaolianum, C. mulanjense, C. pearsonianum (a substitute name for Cynanchum pearsonii), C. sarcomedium (a substitute name for C. intermedium), and C. socotranum. In addition, six subspecies of Cynanchum viminale are newly combined: C. viminale subsp. australe, C. viminale subsp. brunonianum, C. viminale subsp. orangeanum, C. viminale subsp. stocksii, C. viminale subsp. thunbergii and C. viminale subsp. welwitschii. Finally, notes on recent introductions from southern Yemen are made, and illustrations of Cynanchum areysianum are provided.