Zingiber discolor Škorničk. H.Đ.Tr, 2015

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 : 213-215

Zingiber discolor Škorničk. H.Đ.Tr ần & Rybková, sp. nov. (sect. Zingiber )

Unique among all Vietnam Zingiber species by its coriaceous leaf blades that are abaxially have a prominent glossy, rich dark purple-violet colour.

Type:— VIETNAM. Khánh Hòa Province, Hòn Bà Nature Reserve, 897 m, 12°06’46.3”N, 108°58’27.1”E, 4 July 2010, Jana Leong-Škorničková, Romana Rybková, Jan Ponert, Tr ần H ữu Đăng, Trịnh T ấn Thành, TrƯƠng Quang Tâm, TrƯƠng Bá VƯƠng HB-96 (holotype VNM, isotype E, PR, SING, Hòn Bà Nature Reserve). Fig. 7 .

Clump-forming rhizomatous herbs. Rhizome brown externally, purple-brownish internally, pleasantly aromatic with mild camphor smell. Leafy shoots up to 1 m long, arching, with 5–20 leaves; base swollen up to 3 cm in diam.; basal 1/4–1/3 of pseudostem leafless; bladeless sheaths 3–5, richly tinged by dark red, glabrous; leaf sheaths green with various degree of red tinge (greener towards the apex of pseudostem), glabrous; ligule up to 5 mm long, bilobed, lobes round, pale green with various degree of red tinge, glabrous, with brownish papery margin (well visible even in dried material); petiole inconspicuous, consisting of light green, glabrous pulvinus; lamina elliptic, up to 16 × 6 cm (gradually smaller towards the apex of pseudostem), coriaceus, smooth (no prominent plication), dark green or with grey-silverish sheen adaxially, dark purple-red and shiny abaxially, glabrous both sides, margin entire, base obtuse, apex attenuate. Inflorescence radical, erect; peduncle up to 3–7(–9) cm long, with 4–8 sheathing bracts; spike up to 9.0 × 3.5 cm, fusiform to ovoid, composed of 10–30 bracts; bracts broadly ovate to broadly elliptic, up to 3.5 × 2.5 cm, greenish to cream at base, plain green or with various degree of reddish tinge towards apex, glabrous on both sides, margin translucent, c. 1 mm broad, enclosing a single flower; bracteole ovate to elliptic, up to 3 cm long, translucent cream to greenish, sometimes with pink tinge, glabrous on both sides. Flower 5–7 cm long; calyx 12–15 mm long, translucent white, sparsely puberulous towards base, apex with 3 inconspicuous teeth unilateral incision 6–8 mm; floral tube 32–37 mm long, cream white at base, pale yellow towards apex, externally glabrous, internally sparsely pubescent in apical part; dorsal corolla lobe ovate-elliptic, up to 28 × 12 mm, cream white to pale yellow with translucent veins, glabrous externally and internally, apex acute; lateral corolla lobes narrowly triangular-ovate, up to 24 × 6 mm, cream white to pale yellow with translucent veins, glabrous externally and internally, apex acute; labellum c. 24 × 14 mm (to 20 mm wide incl. the staminodes), ovate to rhomboid, often with retuse or emarginate apex; pale yellow at base, with rich purple-red to dark maroon tinge and numerous pale yellow blotches; lateral staminodes 14–15 × 4–7 mm, elliptic to narrowly obovate, connate to labellum by basal 2/3–3/4, cream white to pale yellow, held upwards (not spreading). Stamen 18–22 mm long (measured unmanipulated); filament 2–3 mm long, 3–4 mm broad, cream to pale yellow, glabrous; anther c. 20 mm long (crest not straightened), c. 4 mm broad, connective tissue pale yellow, glabrous, anther crest c. 13 mm long (straightened), pale yellow, wrapped around style, apex acute; anther thecae 10–12 mm long, dehiscing along the entire length. Epigynous glands two, c. 4 mm long, c. 0.6 mm in diam. at base, yellow. Ovary c. 4.0–4.5 × 3.0–4.0 mm, ovoid to cylindric, cream white, glabrous. Style white, glabrous, stigma c. 1 mm long, slightly thicker than style, ostiole front-facing, ciliate. Mature fruits not seen.

Etymology:— The specific epithet is derived from Latin, reflecting that the two faces of its leaf blades are unlike in colour.

Distribution & IUCN preliminary assessment:— Apart of the type locality, this species has been also observed in forests in Lâm Đồng Province, Bảo Lâm district (Nuraliev 830, photographic record of flowering material seen), which is distanced c. 200 km (air distance) from Hòn Bà mountain. It is expected that this species will be reported from other localities in near future.

Ecology and phenology:— Flowering at type locality occurs in May to July, young fruits were observed in July and it is expected that fruiting continues until September. Bảo Lâm populations have been observed to flower in April (M. Nuraliev, pers. com.).

Other specimens examined (paratypes):— VIETNAM. Khánh Hòa Province, Cam Lâm District, Hòn Bà Nature Reserve , 1541 m, 12°07’00.0”N, 108°56’43.9”E, 30 June 2011, Jana Leong-Škorničková, Romana Rybková, Jan Ponert, Tr ần H ữu Đăng, Trịnh T ấn Thành, TrƯƠng Quang Tâm, TrƯƠng Bá VƯƠng HB-31 ; Lâm Đ ồng Province, B ảo Lâm District , L ộc B ắc municipality, 14 km WNW from L ộc Thắng town, 11°44’38’’N, 107°42’22’’E, 1000 m, 16 April 2013, M. S. Nuraliev 830 ( MW, photo seen) .

Zingiber discolor is readily recognized even in its sterile stage by the coriaceous leaves that are prominently coloured below with a glossy, rich, dark purple-violet, a character so far unique to Zingiber species in Vietnam. The upper side of the leaves can be either mid to dark green or with a greyish silver sheen. The colour of the bracts varies from plain green to brownish red (see Fig. 7 C, D ).

Figures

FIGURE 7. Zingiber discolor. A. Habit. B. Detail of ligules. C–D. Inflorescence (note the difference in colour of bracts) E. Flower (front view). F. Detail of ovary with epigynous glands and anther (side and front view). G. Dissection (from left): Floral tube with ovary, calyx and stamen attached, dorsal corolla lobe, two lateral corolla lobes, labellum, bracteole and fertile bract (scale bar in cm). Photo: Jana Leong-Škorničková.