Aspidistra tenuistyla and A. luteo-rubra (Asparagaceae, Convallarioideae), a new tubuliflorous species from northern Vietnam

This study establishes two new species, Aspidistra tenuistyla and A. luteo-rubra (Asparagaceae, Convallarioideae). The first one, Aspidistra tenuistyla, is described here as a new species for science. It was discovered in the lowland limestone area of Ba Be National Park (Bac Kan Province). A detailed illustrated description of this species, along with data on its distribution, ecology, and phenology, is provided. According to the criteria of the IUCN Red List, the conservation status of A. tenuistyla is estimated as Near Threatened (NT). Additionally, the species rank is proposed for A. luteo-rubra, the plant regarded earlier as a variety (A. lutea var. luteo-rubra). It was found in the limestone area of Ngoc Son-Ngo Luong Nature Reserve (Hoa Binh Province). Both plants belong to the group of species with narrowly tubular flowers and are most closely related to A. lutea. A detailed, illustrated comparison of A. tenuistyla, A. lutea, and A. luteo-rubra is additionally presented. All these species are endemic to the limestone regions of northern Vietnam.