Tupistra gracilis Averyanov & N. Tanaka, 2017

Nguyen, Khang Sinh, Averyanov, Leonid V., Тanaka, Noriyuki, Konstantinov, Eugene L., Maisak, Tatiana V. & Nguyen, Hiep Tien, 2017, New taxa of Peliosanthes and Tupistra (Asparagaceae) in the flora of Laos and Vietnam and supplemental data for T. patula, Phytotaxa 312 (2), pp. 199-212 : 207-209

Tupistra gracilis Averyanov & N. Tanaka , sp. nov. ( Fig. 5 ).

Type:— VIETNAM. 22 November 2016, L. Averyanov, CPC 6721a (holotype, LE!). Type specimen prepared from cultivated plant originally collected in northwestern Vietnam (Thanh Hoa province, Thuong Xuan district, Bat Mot municipality, Duc village, Xuan Lien Natural Reserve, primary broad-leaved evergreen forest on rocky, highly eroded, crystalline limestone at elevation 800–1000 m a.s.l. around point 20°01′11.6′′N, 104°57′47.5′′E, 4 November 2013, L. Averyanov, N. T. Hiep, N. S. Khang, N.D. Thang, L. V. Tien, CPC 6721).

Terrestrial and lithophytic rosulate perennial rhizomatous herb. Rhizome thick, creeping, ascending at apex, usually simple, terete, stout, yellowish–brown, (5–)10–25(–40) cm long, Ø (2–)2.5–3(–3.5) cm, covered with black, coriaceous or papyraceous, partially disintegrated remnants of bracts and leaf sheaths. Roots sparse, cord-like, almost straight in basal part, fleshy, Ø (5–)6–8(–10) mm, densely covered throughout with white to light gray root hairs. Stem erect, short, (3–)4–6(–10) cm long, covered with distichous, conduplicate leaf bases and cataphylls. Cataphylls straight, ensiform, acute, (6–)8–20(–22) cm long, (0.4–)0.5–1.5(–2) cm wide (when flattened), base abruptly widened to 6 cm wide, conduplicate, light green, slightly glaucous, soon becoming dry, coriaceous or papyraceous, and almost black, withering earlier than foliage leaves. Leaves (5–)6–8(–10), basal, erect to oblique, equitant, indistinctly petiolate, narrowly oblanceolate, gradually tapering to rigid, canaliculate, petiole-like base, acute at apex, (0.6–)1–1.4(–1.6) m long, (4–)7–9(–11) cm wide, rigid, leathery, uniformly green, glossy, midvein strongly prominent abaxially, persistent 2 or more years. Peduncle arising from apical part of stem, axillary, erect, straight, becoming slightly thicker upward, irregularly angled, naked, fleshy, rigid, (4.5–)6–7(–8) cm long, Ø (4–)5–6(–7) mm ( Ø 3–4 mm when dry), white with pink tint. Inflorescence a dense spadix-like spike of many flowers, (20–)22–26(–30) cm long, Ø 1.5–2.5 cm; rachis irregularly several-angled longitudinally, fleshy, with shallow flower pits. Floral bracts (usually) 1 per flower, lying below flower, bail-shaped, rather fleshy, white or greenish, transversely rectangular, during anthesis 3.5–4 mm long and wide, truncate to acute at apex, in fruit becoming dry, black, coriaceous. Flowers many, sessile, shallowly campanulate, broadly open, (0.8–)1–1.2(–1.4) cm across; perigone 6-cleft distally, dull yellowish, fleshy, the proximal syntepalous (tubular) part 2–2.5 mm long (high), the distal segments triangular ovate, obtuse, flat, strongly recurved apically, (2.8–)3–4(–4.2) mm long and wide. Stamens 6; filaments shortly cylindric, slightly incurved, 1–1.2 mm long, Ø 0.8–1 mm, fleshy, dull yellowish; anthers positioned at sub basal portion of perigone segments, dorsifixed, broadly ovoid, (0.8–)0.9–1(–1.1) mm long and wide, rich yellow. Pistil mushroom-shaped, usually slightly ascending, (9–)10–12(–14) mm long. Ovary externally indistinct, slightly inflated and broader than style, glossy, 1.5–1.8 mm long and wide, 3-loculed, each locule with 1–2 ovoid ovules on axial placentae. Style columnar, slightly broadened upward, (8–)9–10(–11) mm long, Ø (0.8–)0.9–1(–1.8) mm, white to dull yellowish, much exceeding anthers in height. Stigma white to slightly yellowish, almost circular or obscurely 3-lobed, convex, papillulate, Ø (3.4–)3.5–4.5(–5) mm, irregularly splitting into 3 lobes at late stage of anthesis. Fruit berry-like, indehiscent.

Etymology:—The specific epithet refers to the slender, elegant spike.

Habitat and phenology:—Primary and secondary broad-leaved evergreen forests on rocky, highly eroded, crystalline limestone at elevations 800–1000 m a.s.l. Terrestrial and lithophytic herb on shady rocky steep limestone slopes. Plant sometimes grows on ground of rocky slopes covered by rather open forests and in large pockets filled with soil, namely not truly epilithic. Flowering in November–December.

Distribution:—Northern Vietnam (Thanh Hoa province, Thuong Xuan district). Local endemic of northern Vietnam.

Taxonomic relationships:— Tupistra gracilis is close to T. khangii Averyanov, N.Tanaka & Vislobokov in Vislobokov et al. (2014: 288), but differs in its stronger preference for limestone areas (vs. non-limestone areas) and by the creeping rhizome (vs. erect, suberect or ascending rhizome), slenderer spike of slightly smaller, yellowish flowers subtended (usually) by one bract (vs. two), and smaller stigmas, Ø 3.4–5 mm (vs. Ø 5.5–7 mm). It also resembles T. hongheensis Hu & Li (2013: 230) described from southern Yunnan, China ( Hu et al. 2013), but is distinguishable by the shorter rhizome to 0.4 m long (vs. to 1 m), longer spike 20–30 cm long (vs. 11–13 cm), flowers subtended by a single bract (vs. 2 bracts per flower, including 1 bracteole), shorter proximal tubular part of perigone to 2.5 mm high (vs. 4 mm high), shorter perigone segments 2.8–4.2 mm long (vs. 7–8.5 mm long), and slightly smaller stigmas to Ø 5 mm (vs. Ø 6–7 mm).

Figures

FIGURE 5. Tupistra gracilis. Digital epitype, L. Averyanov, CPC 6721a. Photos, correction and design by L. Averyanov.