Pteris langsonensis Li Bing Zhang, Liang Zhang & Ngan T. Lu, sp. nov.
VIETNAM. Lang Son Province: Huu Lung District, Huu Lien Commune, 21°39'33.53"N/106°22'03.74"E, in the acidic soils in the evergreen forest, 200-220 m, 20 November 2013, L.-B. Zhang, L. Zhang & N. T Lu 6593 (holotype VNMN-2015.00100!, isotypes CDBI!, MO!, VNMN!).
Geographical distribution:—Pteris langsonensis is only known from Huu Lien Commune, Huu Lung District, Lan Ti Village, Lang Son Province, northern Vietnam. The two populations of the new species were observed to occur in a moderately disturbed evergreen forest by a large lake. It is possible that the new species occurs in the mountains with acidic soils developed from limestones in the adjacent provinces of Vietnam yet to be explored.
Ecology:—Pteris langsonensis was observed to grow in wet acidic soils in the rainforest, at elevations between 200 and 220 m. Both populations were by a lake and 2 to 3 m away from the water surface.
IUCN Red List category:—Only two large populations with about 50 individuals of Pteris langsonensis have been found. The status of the new species can be classified as Critically Endangered (CE), based on current information and following the IUCN (The International Union for Conservation of Nature and Natural Resources) guidelines (IUCN Standards and Petitions Subcommittee, 2014), but more extensive fieldwork in surrounding similar habitats is needed to accurately assess its conservation status. The habitat and its surrounding regions are located in the protected Huu Lien Nature Reserve, Lang Son Province..
Etymology:—The species epithet longsonensis is derived from the name of the province in northern Vietnam, Lang Son, where the plants were found.
Full version of this species publication is on Phytotaxa 23S (3); 2S3-2S7 with authors includes LIANG ZHANG1 (Chengdu Institute of Biology, Chinese Academy of Sciences, P.O. Box 416, Chengdu, Sichuan 610041, China / Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri 63166-0299, U.S.A), NGAN THI LU (Chengdu Institute of Biology, Chinese Academy of Sciences, P.O. Box 416, Chengdu, Sichuan 610041, China / Department of Botany, Vietnam National Museum of Nature, Vietnam Academy of Science and Technology, 18th Hoang Quoc Viet Road, Cau Giay, Ha Noi, Việt Nam) và LI-BING ZHANG (Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri 63166-0299, U.S.A).