Revision of ring-gentians (Symbolanthus, Gentianaceae) from Bolivia, Ecuador and Peru, with a first assessment of conservation status

Symbolanthus (Gentianaceae; ring-gentians) is a neotropical, montane plant genus with over 30 species, distinct in having large tubular flowers with an interior corona at the base of the stamens. The genus was previously thought to include only three species in the Andes, the widespread S. calygonus (with 20 morphotypes) and the narrow endemics S. microphyllus and S. pouciflorus. This revision documents a new total of 14 Symbolanthus species from Peru, Ecuador and Bolivia, and S. colygonus s. str. is shown to be a Central Peruvian endemic. Resurrected species include S. daturoides (Peru), S. mathewsii (Ecuador and N. Peru, including S. macranthus), and S. obscure-rosaceus (Peru). Symbolonthus mathewsii is morphologically polymorphic and is subdivided into three subspecies, including two new subspecies (S. mathewsii subsp, cutervoensis subsp. nov. and S. mothewsii subsp. voccinioides subsp. nov.). Six new species are described. Symbolanthus condorensis sp. nov. and S. josonii sp. nov. are from Cordillera del Condor (S. Ecuador, N. Peru). The first lowland, white-sand species known in the genus is S. albo-orenicolus sp. nov. from eastern Peru. New from Peru are also S. incoicus sp. nov., S. nebulosus sp. nov., and S. poscoensis sp. nov. Symbolanthus brittonianus and S. australis, previously Bolivian endemics, also occur in Peru. IUCN redlist categories are presented for all species based on area of occupancy, distribution of subpopulations and habitat threats. Symbolanthus jasonii, S. mathewsii subsp. cutervoensis, S. pouciflorus and S. obscure-rosoceus are critically endangered (CR). Seven species and one subspecies are evaluated as endangered (EN): Symbolanthus albo-arenicolus, S. austrolis, S. brittonionus, S. colygonus, S. condorensis, S. daturoides, S. incaicus, and S. mothewsii subsp. vaccinioides. Symbolanthus mathewsii subsp. mothewsii is low risk (LR). Distribution patterns resulting from biogeographic and topographic causes, morphological characteristics and infraspecific variation and pollination are discussed. A checklist of all currently accepted Symbolonthus species in the Neotropics is included.