Zingiber atroporphyreus 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 : 204-206

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

Similar to Zingiber cardiocheilum Škorničk. & Q.B.Nguy ễn (see below) in habit and its narrowly ovate lamina and pendent inflorescences, but differs in the ovoid shape of the inflorescence, larger bracteoles c. 18 × 7 mm, dark purple, almost black labellum with emarginate apex, and longer calyx c. 16 mm long (vs. narrowly fusiform inflorescence, bracteoles 4–10 × 2–4, bright to dark red entire labellum, calyx 12 mm long).

Type: — VIETNAM. Phú Thọ Province, Tân SƠn Dist., Xuân SƠn N. P., 21°07’07.3”N, 104°57’05.2”E, 446 m, 20 August 2014, Q. B. Nguyễn VNM-B0002177 (holotype SING, isotype E, P, VNMN). Fig. 2 .

Clump forming rhizomatous herbs. Rhizome to 1.2 cm in diam., branched, 3–5 cm between leafy shoots, externally light brown, internally pale ochraceous, weakly aromatic, scales broadly triangular, up to 1.5 cm long, tinged pink when young (soon decaying). Leafy shoot to 1.8 m tall, with 20–25 leaves, base swollen c. 15 mm in diam, red, basal 1/2 of pseudostem leafless; bladeless sheaths green with faint dark red tinge towards base; leaf sheaths dark green, mostly glabrous, sparsely pubescent at apical part; ligule 3–5 mm long, shallowly bilobed, light green, sparsely pubescent; petiole absent; lamina narrowly ovate, up to 30 × 2.5–3.7 cm, gradually tapering to narrowly acute apex, base rounded to weakly subcordate, above dark glossy green, smooth (no prominent plication), lighter green beneath, fairly leathery, glabrous both sides. Inflorescence terminal, hanging down; spike 6–7 cm long, c. 2 cm broad, ovoid to narrowly ovoid, consisting of 25–45 bracts; bracts glossy green, broadly ovate, lowermost c. 5 bracts sterile, up to 2.6 × 2.8 cm (gradually smaller towards the apical part of inflorescence), glabrous externally and internally, apex broadly acute to obtuse; enclosing 3 flowers per bract (possibly 2 or 1 in upper bracts). Bracteole narrowly ovate, outermost 18 × 7 mm (inner two gradually smaller), unequally folded with one keel, translucent white, glabrous externally and internally. Flower 3.5–4.0 cm long; calyx c. 16 mm long, translucent white, glabrous, apex truncate with two inconspicuous teeth, unilateral incision c. 7 mm; floral tube c. 22 mm, externally and internally white, externally glabrous, internally puberulous; dorsal corolla lobe ovate-triangular, 15 × 10 mm, semi-translucent pale yellow, externally and internally glabrous, apex acute, mucronate, mucro c. 1 mm, margins incurved; lateral corolla lobes ovate triangular, c. 14 × 6 mm, semi-translucent pale yellow, externally and internally glabrous, apex minutely mucronate (c. 0.5 mm); labellum c. 12–14 mm long, c. 11 mm broad, ovate, dark purple, almost black, sometimes with sparse pale yellow blotches near margins, velvety in appearance, apex emarginate, margins slightly reflexing; lateral staminodes 4 × 2 mm, ovate to triangular, connate to the labellum by basal 2/3, yellow, sometimes with dark purple tinge. Stamen 12–13 mm long (with anther crest not straightened); filament 2 mm long, 4 mm broad at base, 3 mm broad at apex, cream-white, glabrous; anther c. 10 × 4 mm (excl. anther crest), connective tissue cream-white, glabrous, anther crest 4–5 mm long, wrapped around stigma, dark yellow with purple streaks, glabrous; anther thecae c. 9 mm long, dehiscing along entire length. Epigynous glands two, c. 6–7 mm long, c. 0.8 mm in diam., cream-white. Ovary cylindrical, 3 × 2.5 mm, white, glabrous, trilocular with central placentation. Style white, glabrous, stigma c. 3 mm long, slightly thicker than style, white, ostiole front-facing, glabrous. Fruit and seeds not seen.

Etymology:— The specific epithet ‘ atroporphyreus ’ is derived from Greek, reflecting the characteristic dark purple-brown colour of the labellum.

Distribution & IUCN preliminary assessment:— So far 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:— Flowering at type locality is from August to September. It is predicted that fruiting occurs from the end of September onwards and may last about two months.

Other specimens examined:— VIETNAM. Phú Thọ Province, Tân SƠn Dist., Xuân SƠn N.P., 21°07’10.8”N, 104°56’47.1”E, 619 m, 12 April 2013, J. Leong-Škorničková, Q.B. Nguyễn & O. Šída JLS-2175 (SING, VNMN).

Figures

FIGURE 2. Zingiber atroporphyreus. A. Habit. B. Detail of ligules in upper part of the leafy shoot (front view on the left, back view on the right). C. Cincinnus of three flowers. D. Flower (side view). E. Inflorescence (in manipulated position, naturally hanging down). F. Dissection (from left): entire flower in side view, calyx, ovary with epigynous glands attached, ventral half of the floral tube with labellum and staminodes attached, style with stigma, dorsal half of floral tube with stamen attached, three corolla lobes (dorsal in the middle), and fertile bract (opened and viewed form inside) (scale bar in mm). Photo: A & B: Jana Leong-Škorničková, C–F: Nguyễn Quốc Bình.