Cyrtandra argentii, a new species of Cyrtandra (Gesneriaceae) from the Philippines, and a review of the C. villosissima group

Cyrtandra argentii Olivar, H.J.Atkins & Muellner sp. nov., endemic to the Philippines and named after George Argent, is herein described and illustrated. Collections associated with this new species are often confused with three other species, namely C.  ferruginea Merr., C. villosissima Merr., and C.  hirtigera H.J.Atkins & Cronk. Distinguishing characters including keys, updated descriptions, distribution maps, and photos of live specimens are provided to aid identification of the four species. Following the International Union for the Conservation of Nature (IUCN) criteria, C. argentii sp. nov. is considered to be Near Threatened (NT) due to its distribution in a zone susceptible to anthropogenic pressure and the lack of any formal protection.