Zingiber skornickovae N.S. Lý, 2016

Lý, Ng ọc-Sâm, 2016, Zingiber skornickovae, a new species of Zingiberaceae from Central Vietnam, Phytotaxa 265 (2), pp. 139-144 : 140-143

Zingiber skornickovae N.S. Lý sp. nov. (sect. Cryptanthium ) Fig. 1 .

Diagnosis: The new species is similar to Zingiber thorelii Gagnep (1907: 169) , but differs in the larger, ovoid to narrowly ovoid (vs. ellipsoid or lanceolate) spikes, 9–13 × 3–4.5 cm (vs. 3–9 × (2–) 3–4 cm), the narrowly ovate and externally densely pubescent (vs. ovate and externally glabrous) bracts with margins undulate (vs. not undulate) and apices narrowly acuminate, loosely twisted (vs. obtuse and not twisted), the elliptic-obovate (vs. oblong-lanceolate) labellum, 28–34 × 18–22 mm (vs. (15–)21–25 × 6–7 mm), dark red-purple to purple-violet with pale yellow to whitish blotches (vs. cream yellow often with pale red-pinkish spots).

Type:― Vietnam. Quảng Ngãi province : Nghĩa Hành district, Hành Tín Đông commune, TrƯờng Lệ villages, Mount D ầu, Gia Qùy stream, 14°51′43″N, 108°48′64″E, 298 m, 13 August 2015, Lý Ngọc Sâm Lý- 688 holotype VNM ; (isotypes P, SING) .

Description: Rhizomatous herbs up to 110 cm tall, forming small clumps, with 1–4(–15) leafy shoots per clump. Rhizome branched, 1.2–2 cm in diam., externally light brown, internally cream, slightly aromatic, covered with light brown triangular scales, 2–3 cm long, glabrous, soon decaying. Leafy shoots slightly arching, with up to 13 leaves, approximately basal 1/3 of pseudostem leafless; bladeless sheaths 3–4, 7–39 cm long, conspicuously longitudinally striate, light green, lower ones with bright red tinge at base, sparsely white pubescent, especially towards margins; Leaf sheaths inconspicuously longitudinally striate, light green, sparsely white pubescent. Ligule bilobed, 3–5 mm long, greenish, membranous, pubescent, apex acute with short ciliae, dry and soon decaying; petiole reduced to a light green pulvinus, slightly pubescent; lamina obovate to elliptic-obovate, 37–50.8 × 6.9–13.9 cm, adaxially light green, strongly prominently plicate, sparsely white pubescent, abaxially paler, white pubescent, apex acuminate, base attenuate with wing-like leaf margins gradually extending towards pulvinus. Inflorescences 1–3, arising near the base of pseudostem, 15.2–23.8 cm long, with 1–2 flowers opening at a time; peduncle partly or fully embedded in ground, 3.7–13.5 cm long, covered by 5–7 sheathing bracts, broadly triangular-ovate, white with red tinge, externally sparsely pubescent; spike ovoid to narrowly ovoid, 9–13 × 3–4.5 cm, consisting of up to 67 loosely imbricate floral bracts; bracts enclosing single flowers, narrowly ovate, 5.5–6 × 1.2–2 cm (smaller towards apical part of inflorescence), cream-white at base, bright red to dark red towards apex, externally densely pubescent, internally glabrous, margins strongly undulating, sparsely pubescent, apex narrowly acuminate, loosely imbricate, slightly twisting; bracteoles narrowly elliptic, 28–32 × 15–16 mm, white-cream with red tinge to deep red towards apex, externally pubescent, internally glabrous, apex short and acute. Flowers exserted from bracts, 7.6–9.2 cm long; Calyx tubular, 14–16 mm long, clasping at base, translucent white, externally puberulous, with unilateral incision c. 14 mm long, apex with three inconspicuous, blunt ciliate teeth; floral tube 40–42 mm, widening gradually towards apex, externally and internally white-cream at base, pale yellow towards the apical part, externally pubescent, internally glabrous at base, sparsely pubescent towards the apical part; dorsal corolla lobe triangular-ovate, 26–30 × 9–10 mm, pale yellow tinged reddish with semi-translucent veins, glabrous, apex acute, concave, slightly hooded; lateral corolla lobes narrowly triangular-ovate, 23–26 × 6–7 mm, pale yellow tinged reddish with semi-translucent veins, glabrous, apex acute, concave; labellum broadly obovate, 28–34 mm long, 18–22 mm at widest point near the middle of labellum (c. 29–32 mm broad inclusive of lateral staminodes), pale yellow at base, the remainder dark red-purple to purple-violet with small yellow or whitish blotches in the basal half of medial line, margin light yellow, deflexed, glabrous, apex bifid with incision 1–2 mm, sometimes obtuse; lateral staminodes obovate, 17–22 × 8–11 mm, pale yellow with semi-translucent veins, connate to labellum by basal 1/3, glabrous, apex obtuse; stamen 20–22 mm long (unmanipulated); filament c. 2 mm long by 2.5–3 mm wide, cream, with sparse short glandular hairs; anther 13–15 mm long (crest not straightened), 3.8–4 mm broad, connective tissue cream-yellow, glabrous; anther crest 14–16 mm (straightened), wrapped around stigma, light yellow with purple tinge towards apex, glabrous; anther thecae 12–14 mm long, dehiscing along the entire length. Epigynous glands two, subulate, 5–6 mm long, c. 1 mm in diam. at base, cream, apex acute. Ovary cylindrical, 5–6 × 2–3.5 mm, cream with rusty pubescence, trilocular with axile placentation; style white, glabrous; stigma rounded, slightly thicker than style, white, ostiole front facing, ciliate. Fruit not seen.

Ecology:— On Mount Dầu, the new species grows near streamside and in the moist and shady understorey of secondary broadleaved forest dominated by dipterocarps at altitudes of 70– 670 m.

front views) and cross-section of ovary (above) (scar bar in mm). Scale bars: A, C–D in 3 cm; B and E in 1 cm. Photo: Ngọc-Sâm Lý.

Phenology:— Zingiber skornickovae was observed in flower in August to September, flowers bloom for a single day, opening around midday and closing in the early evening (18:00–20:00).

Etymology:— The specific epithet is named in honour of Dr. Jana Leong-Škorničková, a ginger specialist at Singapore Botanic Gardens, for her remarkable and continuing contributions to the study of Indochinese gingers.

Distribution and IUCN preliminary assessment:— Vulnerable (VU B1a,b(iii)). Twenty subpopulations of 5–30 scattered mature clumps were observed on Mount Dầu with a total area of 6.5 km 2 (650 ha). In addition to the type locality, this new species has also been observed in forest in SƠn Trà Nature Reserve (Ðà Nẵng City), with a total area of 400 km 2, where several mature individuals of this species were found along the banks of a small streamlet at 16.134900N, 108.251970E at 449 m elevation (Nguyễn Thành Luân, per. comm., photographic record of flowering material open in the evening). This site is about 150 km northeast of Mount Dầu. The Extent of Occurrence (EOO) is estimated to be less than 20,000 km 2 ( Fig. 2 ). Although this species is under the protection of the local authorities of TrƯờng Lệ and Khánh Giang communes (Quảng Ngãi province) and the SƠn Trà Nature Reserve (Ðà Nẵng City), these populations are, however, vulnerable and continuing to decline in area, extent and quality of habitat due to destruction through human activities, such as harvesting of non-timber forest products (medicinal plants, rattans…), forest fires, and especially clearing of forest land for Acacia plantations. According to the IUCN Red list criteria ( IUCN, 2012), this qualifies it as Vulnerable VU B1ab(iii) which is therefore proposed here. Further exploration of the area around Mount Dầu is needed to understand the situation better and amend the conservation status if necessary.

Additional specimens examined (Paratypes):— VIETNAM. Quảng Ngãi Province : Nghĩa Hành district, Hành Tín Đông commune, TrƯờng Lệ village, Mount D ầu, Nhự hill, 14°52′06″N, 108°48′43″E, 324 m, 13 August 2015, Lý Ngọc Sâm Lý-687 (VNM) ; the same locality, 14°52′06″N, 108°48′43″E, 324 m, 13 August 2015, Lý Ngọc Sâm Lý-689 (VNM) ; the same locality, Chí stream, 14°52′51″N, 108°49′02″E, 76 m, 9 August 2015, Lý Ngọc Sâm Lý-667 (VNM) .

Notes: — Zingiber skornickovae is placed in section Cryptanthium due to its peduncle being partly or fully embedded in the ground. Species of Zingiber sect. Cryptanthium are most diverse in China and Thailand ( Ye et al. 2015, Leong-Škorničková et al. 2015). In Vietnam, at least six species were currently reported in this section ( Theilade 1999, Wu & Larsen 2000, Triboun et al. 2014, Nguyễn 2011, Leong-Škorničková et al. 2015): Z. aff. rubens Roxburgh (1810: 348) , Z. mioga Roscoe (1807: 348) , Z. thorelii Gagnepain (1907: 169) , Z. mekongense Gagnepain (1907: 168) , Z. lecongkietii Škorničkova & Tr ần (2015: 202) and this new species. Zingiber skornickovae shows similarities to Z. thorelii that is distributed to Laos and the central highlands of Vietnam in the characters of general vegetative habit, ligule, peduncle length, the shape of lamina, spike, the shape and size of calyx and corolla lobes. The compared characters between them are given in the above diagnostic. Z. Skornickovae is also distinct from Z. thorelii by the red, pubescent leaf sheath, larger bracteoles 2.8–3.2 × 1.5–1.6 cm and sparsely pubescent, pale yellow corolla lobes and larger lateral staminodes, 17–22 × 8–11 mm while the latter has green and glabrous leaf sheaths, shorter bracteoles 2.4– 2.6 × 0.5–0.6 cm and glabrous, red corolla lobes, smaller lateral staminodes 13–15 × 7–8 mm. Zingiber skornickovae is also similar to Z. recurvatum Tong & Xia (1987: 470) from Southern Yunnan, China ( Tong & Xia 1987) in having a sessile petiole, the shape of corolla lobes being ovate to narrowly ovate and the broadly obovate labellum. Zingiber recurvatum differs from Z. skornickovae by the much taller leaf shoot 2–3 m, longer ligules 8–11 mm, densely brown pubescent, larger lamina 44–55 × 11–15 cm with surfaces hairy, smaller pike ovoid or capitate, 7–9 × 6–7 cm, bracts ovate-orbicular or broadly-ovate to elliptic and glabrous, longer bracteoles red, ca. 4.5 mm, longer calyx ca. 19 × 6 mm with bilobed apex, corolla lobes red with pale base, larger labellum 33–35 × 32–33 cm, white with red spots, larger lateral staminodes auriculate, ca. 15 × 8 mm, white. A key to the species of Zingiber sect. Cryptanthium in Vietnam is provided below.

Figures

FIGURE 1. Zingiber skornickovae. A. Habit. B. Detail of ligules in upper part of young leaf shoot (front view at left and close-up at lower centre) and mature leaf shoot (front view at right and close-up at upper centre). C. Inflorescences with rhizome and leaf shoots. D. Closeup of spike with front and side views of flowers. E. Close-up of flower. F. Dissection of flower (from left): Bracts (external and internal views), flower, bract, bracteole, dorsal corolla lobe and two lateral corolla lobes (above), labellum with lateral staminodes connate to it (below), floral tube with ovary, calyx and stamen attached (scale bar in cm). H. Detail of ovary with epigynous glands and anther (side and

FIGURE 2. Distribution map of Zingiber skornickovae in Mount Dầu and SƠn Trà Nature Reserve.