Zingiber aureolinum N.S.Lý & Škorničk., 2025

Lý, Ng ọc-Sâm, Nguy ễn, Hùng-Quy ền & Leong-Škorničková, Jana, 2025, Zingiber aureolinum (Zingiberaceae: Zingiberoideae), a new species from Central Highlands, Vietnam, Phytotaxa 694 (2), pp. 193-200 : 194-197

Zingiber aureolinum N.S.Lý & Škorničk. sp. nov. (sect. Cryptanthium) Figs. 1 & 2 .

Diagnosis: Similar to Zingiber pauciflorum Bai et al. (2018a: 2) in creeping rhizomes, overall habit, and the shape of the inflorescences, but differs in the adaxially scattered pubescent leaf blades (vs glabrous), calyx with truncated apex (vs. apex minutely toothed), corolla lobes bright yellow rarely with sparse reddish dots (vs white), labellum and staminodes uniformly bright yellow (vs. white predominantly purple labellum, and staminodes white at base with purple apex), anther with yellow connective tissue (vs. white) and orange-yellow anther crest (vs white at base and dark purple apically on Z. pauciflorum ).

Type:— VIETNAM. Kon Tum Province, Kon Plong District, Mang Canh Commune, Tu Rang Village , 14°36′05.07′′N, 108°15′20.36′′E, 1109 m elev., 11 October 2021, Lý Ng ọc Sâm & Nguyễn Hùng Quy ền, Lý-1563 (holotype: VNM; isotype: SING) .

Description: —Terrestrial perennial rhizomatous herbs, up to 60(–80) cm tall, spreading and forming colonies, intervals between pseudostems 7.3–15 cm. Rhizome fibrous, well-elongated and running, 0.5–0.9 cm in diam., branched, individual branches 3.5–16 cm long, internodes 1–3.2 cm long, externally dull brown and covered by light brown/straw coloured triangular scales, internally cream, slightly aromatic; scales triangular ovate, 0.8–1.7 cm long, 1–2 cm wide, apex obtuse, with a mucro ca. 1 mm, sparsely pubescent, soon decaying; root tubers not seen. Leafy shoots arching, each shoot consisting of 7–16 well-developed leaf blades at flowering, distributed on distal 1/2–2/3 of the pseudostem; bladeless sheaths 3–4, tubular near the base, 2.8–23 cm long, obscurely longitudinally striate, light green, sparsely pubescent, margins membranous, hyaline; leaf sheaths inconspicuously longitudinally striate, light green, sparsely pubescent; ligule bilobed, 2.5–5 mm long, pale green, hyaline, with some appressed hair, glabrous towards margin, apices obtuse; petiole sessile, consisting of pulvinus only, 3–7 mm long but shorter in most basal and most distal leaves, pale green, somewhat semi-translucent, sparsely pubescent; leaf blade narrowly ovate to elliptic, (15–)18–27 × (2.5–) 3.5–5.5 cm, plicate, adaxially green, glabrous, sometimes with very few scattered appressed hairs, abaxially dully light green, with silky white appressed hairs (denser towards midrib), base equal, cuneate to attenuate, apex long acuminate, margin hyaline, very narrow, glabrous. Inflorescence 1–3 per plant, radical, arising from the rhizome and distanced 1.5–6 cm from the base of pseudostem; peduncle procumbent, (4–) 6–12 cm long, 4–5 mm in diam., whitish, pubescent (hairs appressed), with 4–7 sheathing bracts, sheathing bracts tubular at base 1/2–1/3, ovate, 1.5–3.8 × 9– 1.6 cm (width when flattened), outer ones shortest, inner ones progressively longer, cream-white tinged with greenish pink, glabrous on both sides, apex obtuse or retuse with a short mucro ca. 0.3 mm long; spike narrowly ovoid to fusiform, 2.8–4.5 × 1.3–1.5 cm, composed of 5–6 loosely arranged bracts, each subtending a single flower; bracts somewhat oblong-ovate with obtuse apex, (2.5–)3.1–3.4 × (0.7–) 1.2–1.6 cm (width when flattened; inner ones smaller), margins strongly incurved and overlapping (giving it a tubular appearance), pale cream to greenish with semi-translucent veins, tinged dark purple distally, adaxially (internally) glabrous, abaxially (externally) sparsely pubescent; bracteoles oblong-ovate with obtuse apex, 2.1–3.1 × 0.8–1.2 cm (width when flattened), adaxially glabrous, externally sparsely pubescent. Flowers (5.5–) 6.7–8.7 cm long, exserted from bracts; calyx tubular, 9–11 mm long, slightly expanded at apex, with unilateral slit 3–4 mm long, semi-translucent white, sometimes with sparse purple tinge, glabrous, apex truncate to very obscurely bluntly three-lobed; floral tube (2.8–) 4–5.3 cm long, narrowly funnelshaped, curved in upper part, 1.5–2 mm in diam. at base, 2.5–4 mm diam. at apex, externally and internally cream white at base, transiting to pale yellow to yellow distally, externally sparsely pubescent, internally glabrous at basal ca. 1/2, distally hairy towards the throat; dorsal corolla lobe triangular-ovate with acuminate cucullate apex, 30–31 × 10– 11 mm, yellow (rarely with sparse reddish dots) with semi-translucent veins, glabrous; lateral corolla lobes narrowly triangular with acuminate cucullate apex, strongly reflexed, 20–27 × 6–7 mm, yellow (rarely with sparse reddish dots) with semi-translucent veins, glabrous; labellum obovate to bluntly rhombic, (24–)28–32 × (14–) 16–20 mm (22–24 mm with lateral staminodes), uniformly bright lemon yellow, glabrous, with slightly crisped margin, apex somewhat acute, obtuse or retuse; lateral staminodes somewhat oblong with apex obtuse to round, somewhat reflexed, 16–20 × 4–5 mm, connation to labellum basally varies widely from ¼ to fully connate, bright lemon yellow with semi-translucent veins, glabrous. Stamen 19–21 mm long (crest not straightened); filament absent; anther 11–12 mm long, 3–3.5 mm broad, connective tissue bright yellow, glabrous; anther thecae ca. 10 mm long, bright yellow, glabrous, dehiscing throughout entire length; pollen pale yellow to white; anther crest beak-shaped, 8–12 mm long (15–18 mm long when straightened), yellow, apex acute. Style filiform, white, glabrous; stigma funnel shaped, slightly thicker than the style, 1–2 × 0.5 mm, ostiole ciliate. Ovary cylindrical, trilocular, 3.5–4 × 2–2.5 mm, pale yellow, densely pubescent; epigynous glands two, narrowly conical with sharp apex, ca. 5 × 0.3 mm, pale yellow. Fruit and seeds not seen.

Phenology: —Flowering in October to November.

Distribution and habitat: —Only known from Kon Tum Province, Kon Plong District, Mang Den Township, where it grows on slopes in shady areas in disturbed primary broadleaved montane forest at elevations of about 850–1200 m a.s.l.

Vernacular name: —Gừng hoa vàng (Vietnamese, meaning yellow-flowered ginger); proposed here.

Etymology: —The specific epithet aureolinum refers to the pure lemon-yellow flowers of this species.

Provisional assessment of IUCN conservation status: —The extent of occurrence (EOO) and the area of occupancy (AOO) of the new species are estimated less than 17.8 km 2 and 12 km 2, respectively. Currently only three subpopulations of about 500 clumps of fertile plants were observed and none occur in an area with any legal status (e.g. such as a National Park or Nature Reserve). Although no uses were reported by the local people, there is a high-risk potential due to loss of the habitat within its range, as vast forested land continues to be cleared for agriculture, ecotourism and residential areas. Based on currently available data we therefore propose to treat this species provisionally under the category of Endangered (EN B1, B2b (i, ii, iii)) according to IUCN Standards and Petitions Subcommittee (2024). Further survey work in the areas adjacent to Mang Den district is necessary to assess the distribution and conservation status of this species more accurately.

Additional specimens examined (paratypes): — VIETNAM. Kon Tum Province, Kon Plong District, Mang Canh Commune, Tu Rang Village, 14°35'30.36"N, 108°15'23.47"E, 1144 m elev., 11 September 2021, Lý Ng ọc Sâm & Nguyễn Hùng Quy ền, Lý-1561 ( VNM) ; Mang Den Township, 14°35'14.41"N, 108°16'39.84"E, 1113 m elev., 16 September 2021, Lý Ng ọc Sâm & Nguyễn Hùng Quy ền, Lý-1567 ( VNM) ; ibid., 14°35'9.86"N, 108°16'37.15"E, 1139 m elev., 16 September 2021, Lý Ng ọc Sâm & Nguyễn Hùng Quy ền, Lý-1568 ( VNM) ; ibid., 14°32'33.4"N 108°15'35.9"E, 891 m, 18 July 2010 Tr ần Hữu Đăng, Lê Công Ki ệt, Nguyễn Duy Linh, Otakar Šída & Vũ Huy Đ ức, Tr ần-264 ( SING —sterile) .

Taxonomic notes: — Zingiber aureolinum has radical inflorescences composed of a procumbent peduncle and a few-flowered spike, both usually partially to fully embedded in the ground with flowers emerging above the ground, and is therefore clearly a member of Z. sect. Cryptanthium. Although the fibrous, elongated and running rhizomes are not rare in Zingiberaceae , they are generally more common in subfamily Alpinioideae rather than Zingiberoideae, where they have been reported infrequently mostly in Curcuma L. (1753: 2) (e.g. ŠkorničkovÁ et al. 2003, Leong-ŠkorničkovÁ & Newman 2015, Tanaka et al. 2020, Saensouk et al. 2021) and Zingiber (e.g. Fang 1982, Bai et al. 2015, 2018a, b). In Zingiber , they are mostly restricted to Z. sect. Cryptanthium and were previously reported in several species in China such as Z. leptorrhizum Fang (1982: 138) , Z. leucochilum Bai et al. (2018b: 2) , Z. pauciflorum and Z. yunnanense Tong & Liu (1991: 27) . Of these, the new species is most similar to Z. pauciflorum to which it was already compared in the diagnosis. It is also somewhat similar to Z. smilesianum Craib (1912: 403) which is known to occur in Thailand, China, Laos (Souvannakhoummane & Leong-ŠkorničkovÁ 2017) and northern Vietnam (Leong-ŠkorničkovÁ, unpublished). However, the new species can be easily recognized from all the species listed above simply by the creeping rhizomes and bright yellow flowers—a character combination not known from any other Zingiber species of Z. sect. Cryptanthium. Additionally, there are differences in phenology of the three species. Flowering period of Z. aureolinum is from October to November, while the flowering of Z. smilesianum occurs earlier, from July to September (Thailade 1999). Flowering of Z. pauciflorum is recorded to occur in September ( Bai et al. 2018b). The yellow flowers of Z. aureolinum may also superficially resemble those of Z. chrysanthum Roscoe (1824 : t. 86), a species native to Indo-Himalayan region from India, Nepal, Bhutan and Bangladesh, and recently also recorded from SE Myanmar ( Aung & Tanaka 2019). However, the two species are unlikely to be confused even in herbarium material due to geographical distance in occurrence of these two species, which even with the recent outlying record of Z. chrysanthum from Myanmar, is well over 1000 km with multiple mountain ranges in between. The two species also have different plant habit, inflorescence and rhizome morphology (far more robust habit with very prominent ligules, inflorescences composed of broad bracts, and compact rhizomes in Z. chrysanthum ).

Figures

FIGURE 1. Zingiber aureolinum N.S.Lý & Škorničk. A. Habit; B. Flowering plant (inset: leaf sheath and ligules); C. Rhizome with inflorescence; D–F. Flowers in different views. A–B and E–G by H.-Q. Nguyễn, C–D by N.-S.Lý. Based on the type collection Lý-1563 (VNM).

FIGURE 2. Zingiber aureolinum N.S.Lý & Škorničk. A. Flowering plant; B. Inflorescence with flower; C. Bracts; D. Flower enclosed in bract and bracteole; E. Dissection of flower (from left): bract, bracteole, calyx, dorsal corolla lobe, two lateral corolla lobes, labellum with lateral staminodes connate, floral tube with stamen and stigma (side view), ovary with two epigynous glands. All photos by N.-S. Lý based on the type collection Lý-1563 (VNM).