Zingiber thorelii Gagnep., 1907

Bai, Lin, Leong-Škorničková, Jana, Xia, Nian-He & Ye, Yu-Shi, 2016, Taxonomic studies on Zingiber (Zingiberaceae) in China III: Z. ventricosum, a new species from Yunnan, and notes on three closely related species, Phytotaxa 261 (2), pp. 101-120 : 111-114

Zingiber thorelii Gagnep. in Bull. Soc. Bot. France 54: 169. 1907. ( Figs. 4C , 8 )

Lectotype (designated here):— LAOS: Bassac [Champasak Province], 1866–1868, C. Thorel 2363 ( P! [barcode P00451016 ]; isolectotypes P! [2×, barcodes P00088650 & P00289183 ]).

Perennial rhizomatous herb 0.4–1 m tall. Rhizomes elongated, almost creeping, 1.2–1.6 cm in diam., light brown externally, pale brownish yellow internally; root tubers spherical fusiform, ca. 1.1 × 0.9 cm. Leafy shoots 1–4 per plant, spreading, each comprising 5–9 well-developed leaves at flowering, basal 1/3 to 2/3 leafless; leaf sheaths pink-red or purplish red, glabrous; ligules reduced, 1–2 mm long, weakly bilobed, membranaceous when young, turning scarious with age, ciliolate, margin sometimes with red; petiole to 3.5 cm long, comprising a pulvinus and the narrowed base of lamina, in some old individuals consisting of pulvinus only, pulvinus 1–9 mm long, sometimes red, slightly pubescent; lamina usually narrowly obovate, sometimes narrowly ovate, 21.5–45 × 6–14 cm, average length:width ratio 2.5–5.2, prominently plicate, adaxially green, sparsely pubescent, abaxially pale green, densely appressed pubescent, base auriculate or attenuate, apex acuminate. Inflorescences 1–3 per plant, radical; peduncle procumbent, 1–4(–12) cm long, ca. 0.6 cm in diam. glabrous, sheathing bracts narrowly ovate to oblong, to 28 mm long (shortest at basal ones, progressively longer distally), white to pink-red; spike ovoid to narrowly ovoid, 5–10 × 2–5 cm, comprising ca. 20 bracts, each subtending one flower (basal two and apical 3–5 bracts sterile); fertile bracts loosely arranged, often leaving the rachis uncovered at flowering, ovate or obovate with a narrowed base, ca. 3–4.1 × 1.6–2.2 cm, usually involute on both sides or on the entire margin, red, sometimes yellowish green, turning red with age, glabrous, apices acute to obtuse; bracteole ca. 23 mm × 11 mm (when flattened), cream-white with red tinge towards the apices, glabrous, apex acute. Flowers ca. 5.5 cm long, much exserted beyond the bracts; calyx tubular, membranaceous, 10–15 mm long, with unilateral incision ca. 2 mm deep, ca. 4 mm in diam., semi-translucent cream-white with slight red tinge, membranaceous, glabrous, apex obtuse; floral tube ca. 3.5–4 cm long, cylindrical at base (ca. 2.5 mm in diam.) to weakly funnel shaped at apex (4 mm in diam.), cream-white; dorsal corolla lobe narrowly ovate, ca. 27 × 11 mm, yellow with more or less dense red tinge, glabrous, apex acute, much deflexed; lateral corolla lobes narrowly ovate, ca. 24 × 7 mm, yellow with more or less dense red tinge, glabrous, apex acute, much deflexed; labellum narrowly ovate to rhombic, ca. 15–25 × 11 mm when flattened, membranous on the margin, thicker in the middle, cream-yellow, often mottled with pale pink or pale purple on the uppers part and the junction with lateral staminodes, glabrous, apex obtuse; lateral staminodes asymmetrically obovate, ca. 10–14 × 9 mm, connate to labellum in the basal ca. 3/4, cream-yellow, glabrous, apices rounded to acute. Stamen ca. 19 mm long (ca. 26 mm long with anther crest stretched); filament absent; anther ca. 11 mm long (excluding anther crest); anther crest beak-shaped, ca. 15 mm long when stretched, bright yellow, apex entire. Style filiform, white; stigma extending upon the end of anther crest, slightly thicker than the style, funnel-shaped. Ovary cylindrical, ca. 5 × 4 mm, trilocular, cream-white, glabrous; epigynous glands two, narrowly conical, ca. 8 mm long, ca. 0.5 mm in diam. at base, cream yellow, apices sharp. Fruits long-ovoid to fusiform, bluntly trigonous septifragal capsule, ca. 22–30 × 7–13 mm, bright red externally, the walls of the valves bright orange red, opening by three valves; seeds obovoid, ca. 9 × 4 mm, black, aril white, sac-like with irregularly edged apex, fully embedding the seeds, longer than the seeds.

Typification: — Gagnepain (1907) did not cite any collections in the protologue of Z. thorelii . Triboun et al. (2007) subsequently regarded the collection C.Thorel 2363 at P (annotated in Gagnepain’s hand as Z. thorelii ) as original material and proposed it as the lectotype. However, there are three specimens of C.Thorel 2363 at P, each possessing a leafy shoot and an inflorescence, and annotated in Gagnepain’s hand. Therefore, in conformity with ICN, Arts. 8.3 and 9.17 ( McNeill et al. 2012), we have narrowed the lectotype designation to a single sheet, namely P00451016, as it also contains notes by the collector and a drawing of the flower structure (see Fig. 4 C ). C.Thorel 2363 was collected during The Mekong Expedition of 1866–1868, at the locality “Bassac”, which is an area located approximately in the Champasak District of southwestern Laos, near the borders of Thailand and Cambodia.

Distribution and provisional IUCN conservation assessment:— Zingiber thorelii is presently recorded only from southern Laos and southern Vietnam. However, future studies may well extend its range to at least northern Cambodia and eastern Thailand. The currently known Extent of Occurrence (EOO) is estimated to be about 84,000 km 2. It is therefore proposed here as globally Least Concern (LC) according to the IUCN criteria ( IUCN 2012, IUCN Standards and Petitions Subcommittee 2014).

Ecology and phenology:—Based on herbarium records Zingiber thorelii has been observed to grow in bamboo forests as well as sandy soil near the stream-inundated forests. It flowers from late July to September. Fruiting phenology has not yet been comprehensively assessed, but judging from flowering and a single fruiting specimen it extends to November.

Additional specimens examined: — LAOS. Champasak Province: Pathoumphone, Bane Thang Beng, Xepiane NBCA, elev. 444 m, 9 September 2006, V. Lamxay VL 1083 ( E, 2×) ; Salavan Province: Lao Ngam, Bane Na Phan Ham , elev. 468 m, 14 September 2006, V. Lamxay & S. Chanthavongsa VL 1113 ( E) ; elev. 1200 m, 23 October 1938, E. Poilane 16116 ( P) ; VIETNAM. Gia Lai Province: Thanh Bình mountain , elev. 552 m, 30 July 2009, H. Đ.Tr ần et al. 180 ( E, SING) ; Kon Ka Kinh National Park , elev. 611 m, 31 July 2009, H. Đ.Tr ần et al. 184 ( SING) ; Bình Thu ận Province: B ắc Bình District, Nam SƠn Commune , Sa Mai Mountain , elev. 964 m, 6 November 2013, Leong-Škorničková et al. JLS-2660 ( SING). Bình Phư ớc Province: Bù Gia M ập National Park (photographic record seen) .

Notes: — Gagnepain (1907) noted the close relationship between Z. thorelii and Z. oligophyllum , stating that they are similar in having a fusiform capsule but Z. thorelii is distinguished by its petiolate leaves. However, like the other two species in “ Z. oligophyllum complex”, both Z. thorelii and Z. oligophyllum often have quite long petioles (comprising of a pulvinus and a narrowed base of lamina), and the narrowed lamina base can be quite short (sometimes entirely absent) on some mature individuals. We have now assessed that the most important differences between these two species are as follows. 1) Corolla lobes in Z. oligophyllum are consistently pale yellow, whereas in Z. thorelii they are yellow with more or less dense red tinge. 2) Lateral staminodes in Z. oligophyllum are narrowly oblong or spathulate and connate to labellum in the basal 1/3, while in Z. thorelii they are asymmetrically obovate and connate to labellum in the basal 3/4. Furthermore, the labella in Z. oligophyllum are pale yellow to yellow whereas in Z. thorelii they are yellow but frequently mottled pale pink or pale purple. 3) Filament is present in Z. oligophyllum but absent in Z. thorelii . 4) Rhizomes are compact in Z. oligophyllum but elongated and almost creeping in Z. thorelii .

The description above is based on the protologue, type material including the attached drawing, and recent collections from Laos and Vietnam.

Figures

FIGURE 4. Type specimens of the four species in “Zingiber oligophyllum” complex. A. Z. ventricosum (holotype, L.Bai 14082601, IBSC). B. Z. oligophyllum (lectotype, A.Henry 1605, K). C. Z. thorelii (lectotype, C.Thorel 2363, P) D. Z. xishuangbannaense (lectotype, S.Q.Tong 24808, HITBC).

FIGURE 8. Zingiber thorelii Gagnep.A. Habit. B. Pseudostem and ligules. C. Rhizomes and infructescences. D. Infructescence (showing the shape and arrangement of bracts). Based on JLS-2660. Photos: Jana Leong-Škorničková.