Some taxonomic clarifications in Vanilla subgenus Xanata (Orchidaceae), and the resurrection of Vanilla calyculata
摘要
Species in the genus Vanilla Plum. ex. Mill. (Orchidaceae) are of economic importance as wild relatives of the natural vanilla crop. Nonetheless, we still lack the taxonomic clarity necessary to effectively conserve and utilise this plant diversity. Colombia is at the centre of the distribution of Vanilla subgenus Xanata section Xanata Soto Arenas & P.J.Cribb, the secondary gene pool for the vanilla crop. We undertook an extensive examination of Colombian national and international herbarium material, including type specimens for Vanilla calyculata Schltr., V. columbiana Rolfe, and V. phaeantha Rchb.f. We provide distribution maps for Vanilla phaeantha and V. calyculata in Colombia, and show that both V. phaeantha and V. calyculata are broadly sympatric within the type location of V. columbiana. Through examination of type material, we reassess the recently-proposed synonymy of Vanilla columbiana with V. calyculata. and concur with previous conclusions that the holotype of V. columbiana is a likely immature bud. Nonetheless, in both floral and vegetative traits, we consider that the greater affinity between Vanilla columbiana and V. phaeantha warrants their synonymy. Consequently, we resurrect the taxon Vanilla calyculata Schltr. Both Vanilla phaeantha and V. calyculata are native to Tropical Dry Forest, a highly threatened ecosystem. With a national Area of Occupancy of only 156 km2 and 68 km2 respectively, both species have a preliminary IUCN Red List classification of Endangered, EN: B2a,b(ii,iii,iv,v) at the national level. Representation of both species in in situ and ex situ conservation strategies requires improvement. With this taxonomic clarity, more thorough conservation evaluation and ecological studies can now be undertaken to inform the management plans for these species.