Taxonomic studies on Parahellenia (Costaceae) in Vietnam: a new species, P. trongduyii, and a new combination, P. candida Author Chen, Juan Key Laboratory of Plant Resources Conservation and Sustainable Utilization / Guangdong Provincial Key Laboratory of Digital Botanical Garden, South China Botanical Garden, Chinese Academy of Sciences, 510650, Guangzhou, People’s Republic of China & South China National Botanical Garden, 510650, Guangzhou, People’s Republic of China Author Nguyen, Van Canh 0000-0001-9853-5510 Institute of Applied Technology, Thu Dau Mot University, No. 6 Tran Van On Street, Phu Hoa Ward, Thu Dau Mot City, Binh Duong Province, Vietnam & nguyenvancanh @ tdmu. edu. vn; https: // orcid. org / 0000 - 0001 - 9853 - 5510 nguyenvancanh@tdmu.edu.vn Author Nguyen, Van Khuong 0000-0002-1264-5178 Institute of Applied Technology, Thu Dau Mot University, No. 6 Tran Van On Street, Phu Hoa Ward, Thu Dau Mot City, Binh Duong Province, Vietnam & nvkhuong @ ttn. edu. vn; https: // orcid. org / 0000 - 0002 - 1264 - 5178 nvkhuong@ttn.edu.vn Author Nguyen, Khang Sinh Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Street, Hanoi, Vietnam & Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Street, Hanoi, Vietnam Author Nuraliev, Maxim S. Joint Russian-Vietnamese Tropical Scientific and Technological Center, Nguyen Van Huyen Street, Cau Giay, Hanoi, Vietnam Department of Higher Plants, Biological Faculty, M. V. Lomonosov Moscow State University, 1, 12, Leninskie Gory, 119234 Moscow, Russia Author Xia, Nianhe Key Laboratory of Plant Resources Conservation and Sustainable Utilization / Guangdong Provincial Key Laboratory of Digital Botanical Garden, South China Botanical Garden, Chinese Academy of Sciences, 510650, Guangzhou, People’s Republic of China & South China National Botanical Garden, 510650, Guangzhou, People’s Republic of China text Phytotaxa 2023 2023-01-31 583 1 72 80 http://dx.doi.org/10.11646/phytotaxa.583.1.7 journal article 53437 10.11646/phytotaxa.583.1.7 344edf21-53fc-463c-a6a5-00a0b5e277b5 1179-3163 7609199 Parahellenia candida (Škorničk., Böhmová & H.Ð.Trẫn) N.H.Xia & Juan Chen , comb. nov. Basionym :— Cheilocostus candidus Leong-Škorničková, Böhmová & Trẫn (2022: 105) . Type :— VIETNAM . Lam Dong Province (cultivated in the Singapore Botanic Gardens, Singapore), collected from cultivation on 21 September 2021 , Leong-Škorničková GRC-421 ( holotype SING ; isotypes E , P , SGN ) . Phenology :—Flowering in the natural habitat was observed in June; in cultivation, it extends to October; fruiting unknown. Distribution, habitat and conservation :—Endemic to Vietnam , occurring near rocky streams in lowland broadleaved evergreen forest, at elevations about 200– 300 m . According to Leong-Škorničková et al. (2022) , there is no reliable information on the population sizes or distribution of this species. It was therefore treated as Data Deficient ( IUCN 2012 ). Notes :— Parahellenia candida is characterized by unbranched or barely branched stems, radical inflorescence, long and narrow floral tube fused with the style base more than halfway (assessed from Fig. 2 in Leong-Škorničková et al. 2022 ) and bilamellate stigma. With these features, this species fits well the concept of the genus Parahellenia . Parahellenia candida is very similar to P. tonkinensis in producing the inflorescence radically, obovate to elliptic leaf blades and bract apex with a sharp mucro, but can be distinguished easily from the latter by its unbranched or barely branched leafy shoots, densely puberulent leaf sheaths, densely puberulous abaxial side of leaf blade and white flowers ( Leong-Škorničková et al. 2022 ).