Tupistra nganii K.S.Nguyen, Aver., N.Tanaka & Nuraliev, 2020

Averyanov, Leonid V., Nguyen, Khang Sinh, Nuraliev, Maxim S., Vislobokov, Nikolay A., Тanaka, Noriyuki, Kopylov-Guskov, Yury O., Lyskov, Dmitry F., Maisak, Tatiana V., Hieu, Nguyen Quang, Kuznetsov, Andrey N., Kuznetsova, Svetlana P. & Thai, Tran Huy, 2020, Tupistra nganii (Asparagaceae), a new species with greenish yellow flowers from northern Vietnam and southwestern China, Phytotaxa 449 (2), pp. 173-180 : 174-178

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).

Figures

FIGURE 1. Plate 0331 of the “Exsiccates of Vietnamese flora”. The plate shows the habit and morphological traits of Tupistra nganii in its locus classicus. The herbarium specimen LE 01042176 (http://herbariumle.ru/?t=occ&id=324) was prepared from the plant shown in the plate. Photos by L. Averyanov and K.S. Nguyen. Design by L. Averyanov and T. Maisak.

FIGURE 2. Tupistra nganii in Tay Con Linh Nature Reserve. A. Habit. B. Inflorescence. C, D. Distal portion of inflorescence with greenish flowers at early anthesis. E. Proximal portion of inflorescence with greenish yellow flowers at late anthesis. F. Longitudinal section of flower. G. Flower, viewed slightly from below. Nuraliev et al., 3025. Photos by M.S. Nuraliev.

FIGURE 3. Distribution map of Tupistra nganii. Red stars indicate the Vietnamese populations; the blue star indicates the population from Yunnan (China). Compiled by M.S Nuraliev and E.S. Popov.