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

TABLE 1. Comparison of Parahellenia trongduyii, P. tonkinensis (based on Chen et al. 2022) and P. candida (based on Leong-Škorničková et al. 2022). ‘-’ denotes lack of data.

Character	P. trongduyii	P. tonkinensis	P. candida
Plant height (m)	0.75‒1.4(‒2.5)	Up to 3	ca. 2
Rhizome indumentum	Glabrous	Densely pubescent	-
Stem branching	Unbranched or barely branched	Densely branched	Unbranched or barely branched
Bladeless sheath
Indumentum	Glabrous	Shortly pubescent	Densely pubescent
Color when old	Reddish brown	Reddish brown	Brown
Axillary bud
Shape	Narrowly triangular-lanceolate	Broadly triangular	-
Indumentum	Glabrous	Densely pubescent	-
Leaf blade indumentum	Glabrous on both sides	Glabrous on both sides	Glabrous adaxially, puberulous abaxially
Bract
Color	Pale brown to reddish brown	Pale brown to reddish brown	Light green
Apex	Softly mucronate	Pungent, making a finger bleeding if touched	Sharply mucronate
Labellum color	Yellow to whitish yellow with longitudinal orange to red lines at center	Yellow with longitudinal red lines at center	White
Anther crest
Length (mm)	9‒12	3–5	3–4
Color	Yellow with longitudinal red lines	Whitish yellow with red bands	White
Dorsal stigma appendage
Shape	Slightly bilobed	Deeply bilobed	-
Color	White	White with red dots at base	-