Phytotaxa 449 (2): 173–180 https://www.mapress.com/j/pt/ Copyright © 2020 Magnolia Press

Tupistra nganii (Asparagaceae), a new species with greenish yellow flowers from northern Vietnam and southwestern China

LEONID V. AVERYANOV1,7*, KHANG SINH NGUYEN2,8, MAXIM S. NURALIEV3,4,9, NIKOLAY A. VISLOBOKOV3,4,10, NORIYUKI ТANAKA5,11, YURY O. KOPYLOV-GUSKOV3,4,12, DMITRY F. LYSKOV3,4,13, TATIANA V. MAISAK1,14, NGUYEN QUANG HIEU6,15, ANDREY N. KUZNETSOV3,16, SVETLANA P.

KUZNETSOVA3,17 & TRAN HUY THAI2,18

1 Komarov Botanical Institute of the Russian Academy of Sciences, 2, Prof. Popov str., 197376 St. Petersburg, Russia.
2 Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology, 18, Hoang Quoc Viet Road, Cau Giay, Hanoi, 100000, Vietnam.
3 Joint Russian-Vietnamese Tropical Scientific and Technological Center, Cau Giay, Hanoi, Vietnam.
4 Department of Higher Plants, Biological Faculty, M.V. Lomonosov Moscow State University, 1, 12, Leninskie Gory, 119234 Moscow, Russia.
5 98-11, Otsuka, Hachioji, 192-0352 Tokyo, Japan.
6 Center for Plant Conservation of Vietnam (CPC),Vietnam Union of Science and Technology Associations, 25/32 Lane 191, Lac Long Quan Rd., Hanoi, Vietnam.
7 av_leonid@mail.ru; https://orcid.org/0000-0001-8031-2925
8 nskhang@gmail.com; https://orcid.org/0000-0001-5171-4140

ISSN 1179-3163 (online edition)

9  max.nuraliev@gmail.com;
10 n.vislobokov@gmail.com;
11 yukinofude@yahoo.co.jp;
12  yurez-kg@yandex.ru; https://orcid.org/0000-0002-3051-8789 13 � rs-lys@yandex.ru; https://orcid.org/0000-0003-0818-1662

https://orcid.org/0000-0001-8291-2633 https://orcid.org/0000-0003-0568-6542 https://orcid.org/0000-0002-8915-8052

14 tmaisak@mail.ru; https://orcid.org/0000-0001-5919-6755
15 nquanghieu@hotmail.com; https://orcid.org/0000-0002-5936-2319 

16 forestkuz@mail.ru; https://orcid.org/0000-0001-5595-1039
17 tropcenterhanoi@mail.ru; https://orcid.org/0000-0002-7610-5058 

18 thaiiebr@yahoo.com.vn; https://orcid.org/0000-0003-1636-9729 *Author for correspondence

Abstract

Tupistra nganii is described and illustrated as a new species from Ha Giang Province in northern Vietnam and Yunnan Prov- ince in southwestern China. The new species is most similar to T. muricata from Thailand and Laos, from which it differs by the greenish white or yellow perianth and longer exserted stamens. Additionally, Tupistra longispica is reinstated on the basis of new morphological evidences.

Keywords: conservation, flora of China, flora of Vietnam, Ha Giang Province, plant taxonomy, plant diversity, Tay Con Linh Nature Reserve, Yunnan Province

Introduction

Tupistra Ker Gawler (1814: 1655) is a genus of herbaceous plants belonging to the family Asparagaceae (APG 2016). This genus inhabits tropical areas of eastern India, Nepal, Bhutan, Bangladesh, Myanmar, southern China, the Indochinese Peninsula and Malesia (Tanaka 2010b, Roy & Mao 2018). Tupistra has a complicated taxonomic history, partly as a result of its uncertain morphological delimitation with respect to the closely related genus Rohdea Roth (1821: 196) which includes Campylandra Baker (1875: 582) (Yamashita & Tamura 2004, Tanaka 2010a, b). Tupistra currently comprises 33 species (Tanaka 2010b, Averyanov et al. 2016, 2019, Nguyen et al. 2017, Roy et al. 2017a, 2017b, Tanaka et al. 2018, Govaerts 2020, etc.), seven of which are known for Vietnam. In Vietnam, the highest species diversity of Tupistra is documented in the northern part of the country, whereas only a few species are known from the central and southern parts (Averyanov & Tanaka 2012, Vislobokov et al. 2014, Averyanov et al. 2016). Here, we describe and illustrate one more new species of Tupistra from mountains at the border between Vietnam and China. Additionally, we show that T. longispica Y.Wan & Xiao H.Lu in Wan (1984: 168) should be regarded as a distinct species. With these additions, the number of species accepted in the genus Tupistra is raised to 35.

Material & methods

Specimens of the new species from northern Vietnam were collected in the field during the years 2013–2019 and herbarium specimens were deposited at HN, LE and MW. The specimens with flowers, available since 2018 only, made possible the identification of these collections. Additional material (including inflorescences) was fixed and stored in 70% ethanol at MW. We also searched for other possible specimens in other herbaria, and we only found a single specimen collected in Yunnan in 2000 preserved at US. Measurements of the floral parts were made on both living and fixed material for all collected specimens (type and paratypes). In the description of quantitative characters, infrequent extreme values (i.e., rarely occurring minimum and maximum values) were parenthesized.

Reinstatement of Tupistra longispica

In the most recent revision of the genus Tupistra, Tanaka (2010: 64) considered T. longispica described from Guangxi, China, to be a synonym of T. muricata (Gagnepain 1934: 287) N.Tanaka (2003b: 335). Since that, more material became available, and currently it appears more plausible to treat T. longispica as a distinct species. Tupistra longispica differs from T. muricata in the perianth turning yellow with ageing (vs. not turning yellow), filaments markedly dilated (vs. indistinctly dilated), and larger (5–7 mm vs. ca. 1.5–4.3 mm in diameter), trisected (vs. slightly trilobed to triparted) stigma. Moreover, the ranges of these two species are widely separated geographically (see below).

Description of the new species

Tupistra nganii K.S.Nguyen, Aver., N.Tanaka & Nuraliev, sp. nov. (Figs. 1, 2)

Differs from the most similar species T. muricata in the greenish yellow or yellow perianth and longer exserted filaments.

Type:—VIETNAM. Ha Giang Province: Quan Ba District, Tung Vai Commune, Thang Village, around point 23.050111oN 104.867278oE, steep rocky slopes of river valley composed with eroded limestone at elevation 1000–1060 m a.s.l., remnants of primary evergreen broad-leaved very humid forest, lithophytic herb with leaves to 2 m long in shady wet rocks, not rare, 19 October 2018, L.V. Averyanov, Nguyen Sinh Khang, T.V. Maisak, Truong Quang Ngan, VR 1015 (holotype HN; isotypes HN, LE, LE01042176, LE01042177, LE01042186 Images of isotypes available at: http://herbariumle.ru/?t=occ&id=324&rid=image_0007111, http://herbariumle.ru/ ?t=occ&id=325&rid=image_0007112, http://herbariumle.ru/?t=occ&id=333&rid=image_0000554).

= Tupistra muricata (Gagnep.) N.Tanaka sensu Tanaka (2010), pro parte (the single specimen from Yunnan, China).

Description:—Herb lithophytic and terrestrial, rosulate, perennial, rhizomatous. Rhizome ascending to erect, usually unbranched, terete, stout, dirty-brown, (10)15–20(30) cm long, thick, (2)2.5–3.5(4) cm in diameter, covered with black, coriaceous, partially disintegrated remnants of cataphylls and leaf sheaths. Roots sparse, almost straight or curved downward in basal part, cord-like, fleshy, (4)5–6(8) mm in diameter, covered throughout with light gray root hairs. Stem erect, short, (2.5)3–4(6) cm long, enclosed by distichous conduplicate leaf sheaths and cataphylls. Cataphylls straight, ensiform or narrowly triangular, conduplicate, light grassy green, (8)10–20(22) cm long, (1)1.5–2(2.5) cm wide (when flattened), tapering to acute apex, with base broad and proximally abruptly widened to 6 cm wide, soon becoming dry, coriaceous and almost black, withering earlier than foliage leaves. Leaves (6)8–10(12), erect, arcuate or pendulous, equitant, oblanceolate, leathery, uniformly green, glossy, (1)1.6–1.8(2) m long, (6)8–10(12) cm wide, acute at apex, tapering proximally to rigid canaliculate petiole-like basal part with sheath-like abruptly broadening base, with midvein strongly prominent abaxially, persistent for 2 or more years. Peduncle axillary (at leaf axil), arising from distal part of stem, erect, oblique or almost horizontal, straight or ascending, slightly thickened upward, obscurely angled longitudinally, naked, fleshy, rigid, light green to almost white, (8)10–12(17.5) cm long, (5)6–8(9) mm in diameter (3.5–4 mm when dry). Inflorescence a dense spadix-like many-flowered spike, (16)18–26(28) cm long, (2)2.2 2.4(2.6) cm in diameter; rachis obscurely and irregularly multi-angled longitudinally, fleshy, with shallow flower pits. Bracts subtending flowers arranged 3.7–5.7 mm below flowers, bail-shaped, obscurely rectangular, rather fleshy, light greenish, during anthesis (1.6)2–3(3.5) mm long and wide, truncate to acute at apex, after anthesis becoming dry, black, coriaceous. Bracteoles (floral prophylls) 1 per flower, in a transversal position, ovoid to rectangular, light greenish, 1– 1.5 mm long, 0.9–1 mm wide, apically acuminate. Flowers sessile, actinomorphic (or slightly zygomorphic with respect to pistil inclination), (1)1.2–1.6(1.8) cm across. Perianth with tube and 6 free lobes, shallowly campanulate, broadly open, greenish white or greenish yellow at beginning of anthesis (in distal part of the spike) and gradually becoming pale yellow (in proximal part of the spike), fleshy; tube cup-like, (3.2)4.4–5.4(5.5) mm long (high); lobes triangular to ovate, obtuse, flat, apically recurved, (4)5–7(8) mm long, (4.2)4.6–5.2(5.4) mm wide. Stamens 6, arranged in tepal radii and basally decurrent to the perianth tube; filaments cylindric, straight or slightly incurved, fleshy, pale yellow, (2)3.2–4(4.2) mm long, 0.9–1.1 mm in diameter; anthers exserted far outside from free lobes of perianth, dorsifixed, broadly ovoid, pale yellowish, (1.5)1.7–1.9(2.1) mm long and wide, thecae laterally opening. Pistil cylindric, erect or slightly ascending, (7.7)10–12(14) mm long. Ovary superior, ovoid, (1.5)2.8–3(3.2) mm long, wider than style, (1.8)2.4–2.6(2.8) mm wide, glossy. Style narrowly cylindric, pale yellowish, as long as stamens or slightly exceeding them, (5)10–11(12) mm long, (0.9)1.4–1.5(1.6) mm in diameter. Stigma convex, obscurely 3-lobed, white to pale yellowish (becoming pale brownish), papillulate, (1.8)2–3.2(3.4) mm in diameter; lobes almost semicircular. Fruit normally 3-seeded, globular, fleshy, dark green, later violet to black, ca. 2 cm in diameter, verruculose, with erect persistent pistil.

Paratypes:—CHINA. Yunnan Province: Maguan, Gu Ling Qing Reserve, 540 m in elevation, 22°43’52” N 103°59’51” E. Deep understory of wet evergreen forest on steep slopes. Herb. Shoots to 1.3 m, leaves distichous, green, stems turn red after cutting. Inflorescence axillary. Flowers yellow, stamens white, 22 November 2000, W.J. Kress, L.M. Prince & Y.M. Xia, 00-6803 (US 00732584). VIETNAM. Ha Giang Province: Quan Ba District, Tung Vai Commune, Thang Village, remnants of primary evergreen broad-leaved very humid forest, occasionally along steep small stream, around point 23.062472°N 104.837194°E, at elevation of 1350–1400 m a.s.l., terrestrial herb, dried flower brown, young fruit green, 13 March 2013, Nguyen Quang Hieu, Nguyen Sinh Khang, Nguyen Tien Vinh, Tu Bao Ngan, Nguyen Van Truong, CPC 4976 (Center for Plant Conservation Herbarium, Hanoi; photo in LE: LE01070256, http:// herbariumle.ru/?t=occ&id=13815), http://en.herbariumle.ru/?t=occ Ha Giang Province: Quan Ba District, Tung Vai Commune, Thang Village, steep rocky slopes of river valley composed with eroded limestone mixed with sandstone, remnants of primary evergreen broad-leaved very humid forest along river, around point 23.05349oN 104.86446oE, at elevation 1000–1100 m a.s.l., terrestrial herb on very steep rocky shady river slope, flowers yellow, common, 7 October 2019, L.V. Averyanov, Nguyen Sinh Khang, T.V. Maisak, VR 1452 (HN; LE01061076, http://herbariumle. ru/?t=occ&id=13037, LE01066967, http://herbariumle.ru/?t=occ&id=12748); Ha Giang Province: Quan Ba District, Tung Vai Commune, Thang Village, remnants of primary evergreen broad-leaved forest on limestone mountains, around point 23.051861° N 104.867361° E, at elevation of 1000–1050 m a.s.l., terrestrial herb about 100–160 cm tall, inflorescence already dried, brown, fruit dark violet to black, locally common on stream bank and steep slopes, 6 March 2019, Nguyen Sinh Khang, Nguyen Phuong Hanh, Tran Duc Binh, Truong Quang Thieu, NSK 1182 (HN; LE 01070257—http://herbariumle.ru/?t=occ&id=13814); Ha Giang Province: Vi Xuyen District, Cao Bo Municipality, Tay Con Linh Nature Reserve, forest on slope, 22.789722°N 104.843333°E, elevation 1220 m, 20 October 2019, M.S. Nuraliev, Yu.O. Kopylov-Guskov, D.F. Lyskov, 3025 (MW0595720, MW0595721; LE 01070259—http://herbariumle. ru/?t=occ&id=13816; living plant cultivated in the Main Botanical Garden of the Russian Academy of Sciences, garden number: 2019.15554.01).

Etymology:—The specific epithet honors Truong Quang Ngan, a local forest explorer and discoverer of the plant.

Habitat and conservation status:—In Vietnam inhabits primary and secondary broad-leaved evergreen humid forests on rocky eroded crystalline limestone or granite at elevations 1000–1400 m a.s.l. Lithophytic and terrestrial herb on shady rocky steep slopes, particularly along streams and rivers. Locally common. In Yunnan, China, Tupistra nganii occurs in the deep understory of the wet evergreen forest on steep slopes at 540 m a.s.l. The estimated IUCN Red List status is DD (following the criteria of IUCN [2019]).

Distribution:―Southwestern China, in Yunnan Province (Maguan County), and northern Vietnam, in Ha Giang Province (Quan Ba and Vi Xuyen Districts). It is thus endemic to an area at the border between Yunnan and Ha Giang (Fig. 3).

Phenology:—Flowering in September–November (possibly December), fruiting in March.

Taxonomic relationships:—Tupistra nganii is characterized by flowers with greenish yellow perianth, which frequently occurs in the genus Rohdea but infrequent in Tupistra. Tupistra, as circumscribed by Tanaka (2003b, 2010b), is distinguishable from Rohdea redefined by Tanaka (2003a, 2010a) by the more slender petiole base, stouter columnar style (almost as thick as the ovary), relatively larger stigma (broader than the style), and usually tuberculate, non-scarlet, spherical berry-like fruit; however, differences between the two genera are narrowed in some cases, e.g. T. siphonantha N.Tanaka, Vislobokov & D.P.Hannon in Tanaka et al. (2018: 32) has fruits similar to those of Rohdea (Tanaka et al. 2018). The flowers of T. nganii may look somewhat similar to those of Rohdea delavayi (Franchet 1896: 40) N.Tanaka (2003a: 331), but the former species is readily distinguishable in having much longer, more slender, leathery, only slightly wavy (vs. flaccid, wavy, significantly wrinkled) leaves and entire (vs. often crenate or fimbriate) perianth segments (along with the features indicated above as diagnostic for the genus Tupistra). Within the genus Tupistra, T. nganii is morphologically close to a group of species with whitish or yellowish widely campanulate perianth such as T. gracilis Averyanov & N.Tanaka in Nguyen et al. (2017: 207), T. hongheensis G.W.Hu & H.Li in Hu et al. (2013: 230), T. khangii Averyanov, N.Tanaka & Vislobokov in Vislobokov et al. (2014: 288), T. longispica, T. muricata and T. tripartita Averyanov, N.Tanaka & K.S.Nguyen in Averyanov et al. (2019: 280). The new species clearly differs from species of this group in the following combination of characteristics: greenish yellow perianth (vs. yellowish or purplish white, except for T. hongheensis with greenish perianth), significantly longer filaments (up to 4.2 mm long, as long as pistil or slightly shorter vs. up to 1.5 mm long, significantly shorter than pistil) and stigma smaller in diameter (2–3.2 mm vs. 3–7 mm, except for T. muricata with stigma usually 1.5–3.5 mm in diameter).

Tupistra nganii morphologically most similar to the species T. muricata in having a widely campanulate perianth with recurved triangular ovate lobes and a small thin (non-incrassate) shallowly lobed stigma. However, it differs from T. muricata by the greenish white to yellow perianth and significantly longer exserted filaments. Therefore, the specimen with a yellow perianth and long filaments cited by Tanaka (2010b) as T. muricata (W.J. Kress et al. 00-6803, US 00732584 from Yunnan) is considered here to fall within the new species and is listed above among the paratypes. In the specimen from Yunnan, which was soaked in alcohol before drying, the stigma was 1.8–2 mm in diameter, and the filaments were 3.5–4 mm long. Accordingly, T. nganii occurs at the border between northern Vietnam and southwestern China, and T. muricata is thus absent in China, being confined to Thailand and Laos. The new species is also similar to T. longispica in having a perianth turning to yellow. Tupistra nganii is, however, distinguishable from T. longispica mainly by the shorter peduncle (8–17.5 cm vs. 20–33 cm long), greenish yellow (vs. externally purplish, internally white) perianth, longer filaments (2–4.2 mm vs. ca. 1 mm long) and smaller stigma (1.8–3.4 mm vs. 5–7 mm in diameter).

Acknowledgements

The authors cordially thank Dr. Nguyen Tien Hiep, Director of the Center for Plant Conservation, Hanoi (Vietnam Union of Science and Technology Associations), for the fieldwork organization, and E.S. Popov for providing the map of Southeast Asia. NT thanks the curators of US for the loan of specimens. The work of LVA, KSN and TVM was financially supported in part by the Vietnam Academy of Science and Technology, project QTRU01.07/18-19 and Russian Foundation for Basic Research, project 18-54-54005 and was carried out in the framework of the institutional research project of the Komarov Botanical Institute of the Russian Academy of Sciences (АААА-А18-118031290070- 6). The work of KSN was supported by the Vietnam National Foundation for Science and Technology Development (NAFOSTED) under grant number 106.03-2018.09. The work of MSN, NAV, YOKG and DFL was supported by the Russian Foundation for Basic Research (project 19-54-54007).

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