Zingiber plicatum Škorničk. & Q.B.Nguy

Leong-Škorničková, Jana, Bình, Nguy ễn Qu ốc, Đăng, Tr ần H ữu, Šída, Otakar, Rybková, Romana & Vương, Trương Bá, 2015, Nine new Zingiber species (Zingiberaceae) from Vietnam, Phytotaxa 219 (3), pp. 201-220 : 211-213

Zingiber plicatum Škorničk. & Q.B.Nguy ễn, sp. nov. (sect. Dymczewiczia)

Zingiber plicatum is unique among all terminally flowering species by its prominently plicate leaves. Its erect inflorescence is similar to Z. castaneum and Z. mellis , but it differs from the first in its bracts not being recurved at apex (vs. bracts recurved at apex) and from the second by its thin prominently plicate lamina, green thin ligules and labellum peach-purple to purple, with cream white or pale yellow lines radiating from the base, margins reflexed (vs. leathery lamina with no prominent plication, thick dark maroon ligules, and labellum dark maroon-brown, with minute yellow streaks broadly trullate, flat).

Type: — VIETNAM. Phú Thọ Province, Tân SƠn Dist., Xuân SƠn N. P., 21°07’07.3”N, 104°57’05.2”E, 446 m, 12 April 2013, J. Leong-Škorničková, Q. B. Nguyễn & O. Šída JLS-2170 (holotype SING, isotype VNMN). Fig. 6 .

Rhizomatous herb. Rhizome to 2.5 cm in diam, creeping, externally light brown, internally ochraceous, weakly aromatic. Leafy shoot to 1 m tall, with 5–10 leaves, basal part of pseudostem c. 1/3 leafless; bladeless sheaths 2–3, usually with vestige of leaves, green, puberulent (slightly rough to touch); leaf sheaths green, puberulent; ligule 3–5 mm long, shallowly bilobed, puberulent; petiole 3–7 mm long; lamina up to 25 × 10 cm, elliptic to broadly elliptic to obovate, apex acuminate to caudate, base obtuse, above bright green, lighter green beneath, prominently plicate, glabrous on both sides. Inflorescence terminal, in upright position; spike 12–18 cm long, 1.5–2.0 cm broad, consisting of 6–17 bracts (topmost 1–2 bracts usually sterile); bracts green (turning yellow with age), glossy, to 3.5–4.0 × 1.7–3.5 cm, elliptic to weakly obovate, with broadly acute to rounded apex, supporting 1–2 flowers; bracteole c. 13 × 4 mm, narrowly ovate-triangular, unequally folded with one keel, translucent greenish, glabrous externally and internally. Flower (described from almost mature flower bud; measurements expected to be slightly larger in fully matured open flowers) c. 5.3 cm long; calyx c. 15 mm long, translucent white, glabrous, with one or two teeth at apex, with unilateral incision 6–8 mm; floral tube c. 18 mm, externally and internally white, externally glabrous, internally puberulent; dorsal corolla lobe ovate triangular, c. 25 × 9 mm, cream-white to pale yellow, sometimes with pink-purple tinge, greenish towards apex, externally and internally glabrous, apex acute, mucronate, mucro c. 1 mm; lateral corolla lobes ovate triangular, 22–23 × 5–6 mm, cream-white to pale yellow, sometimes with pink-purple tinge, greenish towards apex, externally and internally glabrous, apex acute; labellum c. 19 × 12 mm, obovate, peach-purple to purple, with cream white or pale yellow lines radiating from the base to about half of the labellum, apex incised c. 2 mm; lateral staminodes c. 12 × 4 mm, oblong, connate to labellum by basal 1 mm, peach or pink-purple at base, fading pale yellow to cream white towards apex, outer sides and apices reflexed. Stamen c. 23 mm long (with anther crest not manipulated); filament c. 1 mm long, 2.5 mm broad at base, cream white, covered with short glandular hairs; anther 24 × 5 mm (with anther crest straightened), connective tissue cream white to yellow, covered by short glandular hair, anther crest 8 mm long, wrapped around stigma, tinged purple or red-purple, glabrous, apex bifid, incision 1–2 mm; anther thecae c. 16 mm long, dehiscing along entire length. Epigynous glands two, c. 3 mm long, c. 0.6 mm in diam., ochraceous. Ovary nearly cylindrical to weakly obconical, 6 × 2–3 mm, cream white, with sparse appressed silky hair, trilocular with central placentation. Style white, glabrous, stigma c. 2 mm long, slightly thicker than style, white, ostiole front facing, shortly ciliate. Fruit and seeds not seen.

Etymology:— The epithet reflects the prominently plicate laminae of this species, which readily distinguishes it from any other terminally flowering Zingiber species in Vietnam.

Distribution & IUCN preliminary assessment:— So far it is known only from the type locality in Xuân SƠn National Park. Although this species is under protection of the National Park, we propose to treat this species provisionally as vulnerable (VU D1 and D2) for the AOO is less than 20 km 2 and less than hundred adult individuals in two subpopulations at one location were encountered during our fieldwork which covered various parts of Xuân SƠn National Park.

Ecology and phenology:— Growing in broadleaved evergreen lowland forest on limestone, at altitude around 400– 500 m. While two inflorescences in buds were found in mid April, this species, according to staff of Xuân SƠn National Park, usually flowers from June to July.

Other specimens examined (paratypes):— VIETNAM. Phú Thọ Province, Thanh SƠn District, Xuân SƠn municipality, Xuân SƠn National Park, near road from Lấp village to the waterfall, 21°08’15’’N, 104°56’15’’E, 250 m, 17 October 2014, M.S. Nuraliev & N.A. Vislobokov 1094 (MW, photo seen).

Figures

FIGURE 6. Zingiber plicatum. A. Habit. B. Inflorescence. C. Rhizome. D. Detail of ligule. E. Flower dissection (from left): floral tube with ovary, calyx and anther (side view), lateral staminodes with labellum in between, lateral corolla lobes, dorsal corolla lobe, bracteole, and bract (scale bar in cm). Photos: A, B, D—Maxim Nuraliev; A (inset only), C, E—Jana Leong-Škorničková.