Tupistra annamensis N.Tanaka, N.S.Lý, K.S.Nguyen & T.S.Hoang, 2022

Lý, Ng ọc-Sâm, Hoàng, Thanh Sơn, Nguyen, Khang Sinh & Тanaka, Noriyuki, 2022, Tupistra annamensis (Asparagaceae), a new species from central Vietnam, Phytotaxa 567 (2), pp. 173-180 : 174-179

Tupistra annamensis N.Tanaka, N.S.Lý, K.S.Nguyen & T.S.Hoang , sp. nov. ( Fig. 1–3 ).

Similar to several species with a pendulous floriferous stem such as T. fungilliformis and T. clarkei , but differs from them and all other members of this genus by its outer and inner floral bracts subsimilar in size and shape, and sharply acute or aristate glumaceous (or dry, papyraceous, brownish) bracts exceeding the flowers.

Type:— VIETNAM. Quang Ngai Province: Tra Bong District, Tra Nham Commune, Mount Ca Dam , 15°10'12.69"N, 108°28'33.31"E, at elevation about 1000 m, January 2021, Ngọc Sâm Lý, Lý-1556 (holotype, VNM!; isotypes, P!, HN!) .

Description: — Lithophytic or epiphytic rhizomatous clustering perennial herb with leaves up to 140 cm high. Rhizome suberect to ascending, terete, branching, 2.8–9 cm long, 1–1.5 cm in diam., stout, slightly woody, densely nodded, light yellowish-brown, covered with remnant bases of sheath-leaves. Roots many, cork-like, fleshy, 3.5–6 mm in diam., light grey, velutinous. Stem erect, 1.5–5 cm tall, covered with leaf sheaths and partially disintegrated fibrous scales. Cataphylls 6–8, basal, enclosing basal part of leaves, equitant, deltoid, narrowly deltoid or subulate, acute, 1.3–14.3 cm long, 1–2.5 cm wide (when expanded), the outermost light pale green, purplish at base, the inner ones green, soon drying, papyraceous and partially disintegrated with age. Leaves (3–)5–6 per shoot, basal, sub-distichous, equitant, suberect or arcuate; petiolar part straight, rigid, adaxially canaliculate, (12) 20–33.5 cm long, 3–5 mm in diam.; blade linear oblanceolate with acute apex, (62–) 101.5–125 cm long, (4.6–)6.5–8,1 cm wide, leathery, dark green, glossy, gradually tapering to base. Floriferous stem (including both peduncle and rachis) (2.2–) 12–22 cm long, yellowish green with purple tint, smooth; peduncle axillary, slightly arching or curved downward, rigid, shorter than inflorescence rachis, (0.4–) 1.2–7.5 cm long, 3–5 mm in diam., with (2–)3–4 sterile bracts (including basal ones); sterile bracts lanceolate or narrowly triangular lanceolate, strongly acuminate, attenuate, aristate or sharply acute, 2.1–3.5 cm long, 1.3–1.5 cm wide at base, yellowish green tinged with purple, light brown in anthesis; inflorescence a spike, 5–22-flowered, pendulous or somewhat horizontally arcuate, rarely sub-erect, (2.5–) 5–14.5 cm long, 2.5–3.5 cm in diam., rachis slightly angled longitudinally, shiny, glabrous. Floral bracts 2 per flower, triangular-ovate or triangular lanceolate, strongly acuminate, aristate, or sharply acute, navicular, exceeding flowers, pale green, externally tinged with purplish red for basal 1/3, herbaceous, but soon becoming dry, papyraceous and dull brown; outer bracts 1.7–3.5 cm long, 1–1.2 cm wide at base, inner bracts slightly smaller, 1.7–2.8 cm long, 0.5–0.7 cm wide at base. Flowers obliquely antrorse, sessile; perianth cupulate or campanulate, 1.1–1.4 cm long, very fleshy; tube bowl-shaped, 5–6 mm long, externally purple, internally dark-purple; lobes 6, triangular-ovate, 6–7 mm long, 4–6 mm wide at base, adaxially dull whitish yellow, abaxially purplish, erect to slightly recurved, acute. Stamens 6; filaments adnate to orifice of perianth tube, cylindric, ascending, 1–1.2 mm long, 0.7–0.8 mm in diam., fleshy, dull whitish yellow, purple at base; anthers dorsifixed, ovoid, introrse, 1.8–2.1 mm long, 0.8–1.1 mm wide, yellow. Pistil 1, 6.5–7 mm long; ovary superior, slightly broader than style, 1.8–2 mm long, ca. 3 mm wide, finely ridged longitudinally, purplish, 3-loculed, each locule with 1–2 ovoid ovules; style columnar, slightly broadened toward apex, 3–4 mm long, 1.2–1.5 mm, tinted with purple, finely ridged longitudinally, glabrous; stigma peltate, irregularly 3-lobed, flat or slightly convex, 3–3.5 mm in diam., roughly warty, yellow, slightly exceeding tube, slightly higher than anthers. Fruit berry-like, subglobose or spherical, indehiscent, dull pale yellow with purple tint, irregularly tuberculate, (1.5–) 2–3 cm in diam., with persistent remnant of style at apex, usually 3-seeded; seeds subglobose, 0.5–1.2 cm long, 0.4–0.8 cm in diam., glossy, brownish yellow.

Additional specimens examined (paratypes):— VIETNAM. Quang Ngai Province: Tra Bong District, Huong Tra Commune, Mount Ca Dam , tropical evergreen broad-leaved forest, 15°10'17.59"N, 108°28'26.31"E, at elevation 982 m, January 2021, Ngọc Sâm Lý, Lý-1553 ( VNM) . Da Nang City: Ba Na Nui Chua NR, 16°0'12.068"N, 108°01'15.746"E, at elevation 682 m, 20 February 2022, Thanh SƠn Hoàng 11406 ( VAFS) .

Distribution:— Quang Ngai Province and Da Nang City, central Vietnam ( Fig. 4 ).

Habitat and conservation status:— Tupistra annamensis occurs as an epiphyte in the remnant primary evergreen broad-leaved forest at elevations around 1000 m in Mount Ca Dam (Quang Ngai Province) or as a lithophyte on granite rocks along a stream in the lowland tropical evergreen forest at elevations around 700 m in Ba Na Nui Chua Nature Reserve (NR) (Da Nang City) ( Fig. 4 ). The two habitats are about 110 km away from each other. In Mount Ca Dam we found 4 clumps of mature plants, while in Ba Na Nui Chua NR we found two colonies each comprising approximately 60 clumps of mature plants. The extent of occurrence (EOO) and the area of occupancy (AOO) were estimated to be less than 54.2 km 2 and 8 km 2, respectively. Although the plants of T. annamensis appear not to be utilized for specific purposes by local people and the forests are officially protected by the provincial authorities or by the board of the NR, there still remains the high potential risk that the forests including the habitats are severely damaged by various human activities such as clearing of the vast forested land for Acacia plantations and harvesting of non-timber forest products including medicinal plants and rattans. Following the IUCN Red List Criteria ( IUCN 2022), we provisionally assess the conservation status of the new species as Critically Endangered; CR B2ab(iii), C1.

Phenology:—Flowering and fruiting in January–February.

Etymology:—The specific epithet is after the former name of the central region of Vietnam ( Annam), from which the new species was discovered.

Vernacular name (in Vietnam):—Khai khẩu tiễn trung bộ, Từ bích trung bộ.

Taxonomic relationships:—In Tupistra , only several species, such as T. fungilliformis F.T.Wang & S.Yun Liang in Wang & Tang (1978: 249) known from northern Vietnam and the southern part of Yunnan, China, and T. clarkei Hooker (1892: 325) from Nepal and northeastern India, have a pendulous flowering stem ( Tanaka 2010a). As T. annamensis also has such a unique stem (apomorphy), it is deemed as closely related to them. Tupistra annamensis and T. fungilliformis also share an epiphytic and lithophytic habit ( T. fungilliformis is also terrestrial) ( Wang & Tang 1978, Nguyen et al. 2017), an externally dark purplish perianths, and fruits with somewhat irregularly purple-striated mottles. Besides, they occur comparatively near to each other in geographical distribution. It is hence likely that T. annamensis is closely allied to T. fungilliformis . Tupistra annamensis is, however, readily distinguishable from T. fungilliformis mainly in having at least two (vs. one) sharply acute larger sterile bracts on the peduncle (excluding those at the base), aristate or sharply acute, herbaceous or papyraceous (somewhat glumaceous) fertile bracts exceeding the flowers (vs. usually rounded to (sub)acute (sub)membranous bracts shorter than the flowers), outer and inner floral bracts subsimilar in size and shape (vs. inner bracts much smaller and dissimilar in shape compared with the attending outer bracts), longer (1.8–2.1 vs. 1–1.5 mm long) anthers adnate to the apex (vs. slightly above the middle or subdistal portion) of the perianth tube, and peltate (vs. more or less hemispheric) stigma. As far as we are aware, no other species of Tupistra have such a relatively large fertile inner bract and aristate or sharply acute glumaceous bracts exceeding the flowers ( Tanaka 2010a). Tupistra annanensis is hence a unique distinct species differing in these traits from all other members of the same genus. The present discovery of T. annamensis brings the total species number of the genus to about 38, and that in Vietnam to 10.

Figures

FIGURE 1. Tupistra annamensis from Quang Ngai Province.A. Plant growing on tree trunk. B. Habit. C. Two flowering stems at different stages of anthesis (the left one younger than the right). D. Basal plant portion with flowering stem, rhizome, roots, etc. E. Young stages of flowering stems and young fruits (white arrow). F and G. Flowering stem. Scale bars: B = 20 cm, C, E–G = 2 cm, D = 1 cm. Photos & layout by N.S. Lý.

FIGURE 2. Tupistra annamensis from Quang Ngai Province. A. Flowering plant. B. Flowering stems. C. Sterile bracts from base (left), middle, and distal portion (right) of peduncle. D. Flowers with bract(s). E. Flower with bracts. F. Floral bracts. G. Longitudinal section of flower showing interior. H. Cross-section of flower showing stamens and stigma. I. Floral tube with stamens, longitudinal-section. J. Pistil longitudinal sectioned and ovary cross-sectioned. ib: inner bract. ob: outer bract. sb: sterile bract. Scale bar (at E):A = 20 cm, B–C = 3 cm, D–F = 20 mm, G–J = 10 mm. Photos & layout by N.S. Lý.

FIGURE 3. Tupistra annamensis from Da Nang City. A–C. Plants on rocks (A, B) or on tree trunk (C). D. Part of mature plant with spike and infructescence. E. Spike. F. Distal part of spike. G. Flower, front view. H. Flower longitudinally sectioned. I. Floral tube with stamens, cross-section. J. Pistil, side view. K. Mature fruits mottled with purple. L. Seeds. Scale bars: D = 5 cm, G–J, L = 5 mm, K = 1 cm. Photos by T.S. Hoang; plate layout by N.S. Lý.

FIGURE 4. Distribution map of Tupistra annamensis in Vietnam. Solid circle (●): Mount Ca Dam, Quang Ngai Province. Solid triangle (▲): Ba Na Nui Chua NR, Da Nang City.