Zingiber xishuangbannaense S.Q.Tong

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 : 114-118

Zingiber xishuangbannaense S.Q.Tong in Acta Phytotax. Sin. 25: 461. 1987. ( Figs. 4D , 9 )

Lectotype (designated here): — CHINA. Yunnan Province: Xishuangbanna, Mengla Xian, Menglun Zhen , Mangang Mountain , elev. 800 m, 12 August [sphalm. July] 1981, S. Q.Tong 24808 ( HITBC! [registration number 081594]; isolectotype HITBC! [registration number 081593], KUN! [2×, barcode numbers 1219346 & 1219347]).

[ Zingiber thorelii auct. non Gagnep.: Triboun, Chantaranothai & Larsen in Acta Phytotax. Sin. 45(3): 403. 2007, as to Thailand occurrences]

Perennial rhizomatous herb 0.8–1.2(– 1.6 m) tall. Rhizomes fleshy, compacted, densely branched, 1.2–2 cm in diam., light brown externally, pale yellow internally; root tubers fusiform, formed distanced from the rhizomes, ca. 2.5 × 1.2 cm, pale brown externally, white internally. Leafy shoots 3–8 per plant, forming dense clumps, usually spreading, each comprising 9–15 well-developed leaves at flowering, basal 1/3–2/5 leafless; leaf sheath s usually burgundy or sometimes pale green, sparsely pubescent; ligules reduced, to 2 mm long, weakly bilobed, green, glabrous, margin rounded; petiole up to 3 cm long, comprising a pulvinus and the narrowed base of lamina, sometimes only comprising the pulvinus, pulvinus sometimes red adaxially, densely pubescent; laminas narrow obovate, narrowly oblong to narrowly ovate, 30–55 × 5.5–12 cm (length:width ratio 2.5–5), adaxially green, thin, prominently plicate, pubescent on both sides of the midvein, hairs silvery, appressed, abaxially pale green, pubescent, hairs silvery, appressed, base attenuate, obtuse to auriculate, apex attenuate. Inflorescences usually 2–3 per plant, arising from the rhizomes close to the base of the pseudostem; peduncle procumbent, robust, 1–5(–12) cm long, ca. 1 cm in diam., glabrous; sheathing bracts ovate to narrowly ovate, 11–35 mm × ca. 2 cm (width when flattened), shortest at basal, progressively longer distally, red or green, apices rounded; spike narrowly ovoid, conical, or horn-shaped, 8–17 × 3–4 cm, comprising up to 50 densely imbricated bracts, each subtending single flower (uppermost 2–5 bracts usually sterile); fertile bracts ovate to obovate, ca. 3.2 × 2 cm, green throughout or with red at apex or red throughout, glabrous externally and internally, apex obtuse to acute or attenuate; bracteole narrowly oblong, ca. 2.2 × 0.9 (width when flattened), yellowish green with brownish red tinge at apex, glabrous externally and internally, apex rounded or slightly emarginate. Flowers ca. 6.5 cm long, slightly exserted beyond the bract; calyx tubular, membranaceous, ca. 9 mm long, with unilateral incision 5 mm deep, semi-translucent cream-yellow, glabrous, apex slightly dentate to truncate; floral tube ca. 3.8 cm long, cylindrical at base (2–3 mm in diam.) to weakly funnel-shaped at apex (ca. 4 mm in diam.), cream-yellow, glabrous externally and internally; dorsal corolla lobe narrowly ovate or oblong, ca. 22 × 8 mm, yellow with dense red tinge, concave, glabrous externally and internally, apex mucronate; lateral corolla lobes narrowly triangular-ovate, ca. 22 × 5 mm, yellow with dense red tinge, usually deflexed, glabrous externally and internally; labellum narrowly ovate, ca. 21 × 8 mm, thin and yellow on the margin, thicker and pale yellow at base, occasionally mottled with pale red or pale purple, apex rounded or attenuate, margin revolute; lateral staminodes asymmetrically obovate, ca. 12 × 5 mm, connate to labellum in the basal 1/2 to 3/4, yellow, slightly paler at base, usually mottled with red at base, apices rounded. Stamen ca. 18 mm long (ca. 20 mm long with anther crest stretched); filament absent; anther 8–10 mm long (excluding anther crest), connective tissue orange yellow, glabrous; anther thecae 8–10 mm long, dehiscing throughout entire length, pollen cream-yellow; anther crest beak-shaped, ca. 10 mm long when stretched, orange yellow, apex entire. Style filiform, cream-yellow, glabrous; stigma extending beyond the tip of the anther crest, slightly thicker than style, 3 mm long, funnel-shaped, white, ostiole ciliate. Ovary cylindrical, trilocular, 4–5 × 4 mm, cream-yellow, glabrous; epigynous glands two, narrowly conical, ca. 8 mm long, 0.5 mm in diam. at base, pale yellow to yellow, apices sharp. Fruits not observed.

Typification:— S.Q.Tong 24808 at YNTBI (now HITBC) was designated as holotype in the protologue of Z. xishuangbannaense . However, there are two sheets of this number at HITBC and their labeling is confusing. One sheet (HITBC registration number 081594) has a type-written remark on the label ‘Holotypus’ but an ink stamp on the sheet stating ‘Isotypus’, while the other sheet (HITBC registration number 081593) has a type-written remark on the label ‘Isotypus’ but an ink stamp on the sheet stating ‘Typus’ (presuming a Holotype). In accordance with ICN (Art. 9.5, Art. 9.11 and Art. 40.2, Note 1) ( McNeill et al. 2012), these specimens are regarded as syntypes and we have selected the first one as the lectotype. The second sheet of S.Q.Tong 24808 at HITBC and the two duplicates at KUN are isolectotypes. The collection date is given as 12 July 1981 in the protologue, but is written as 12 August 1981 on all duplicates of S.Q.Tong 24808 that we have seen. We have observed that other S.Q.Tong collection with collection numbers lower than 24808 were gathered after 12 July 1981 (e.g. S.Q.Tong 24804 collected on 20 July 1981; S.Q.Tong 24806 collected on 6 August 1981). Also, based on our field observation, Z. xishuangbannaense usually flowers from mid-August to mid-October. We therefore consider that the July date given in the protologue is a typographic or unintentional error and is here corrected to August.

Distribution and provisional IUCN conservation assessment:— Zingiber xishuangbannaense occurs in Yunnan Province in southwestern China, northern Laos and in Thailand (except the Peninsular Region). The known Extent of Occurrence (EOO) of this species is about 438,000 km 2. It is therefore proposed as globally Least Concern (LC) according to the IUCN criteria ( IUCN 2012, IUCN Standards and Petitions Subcommittee 2014).

Ecology and phenology:—In Yunnan Province Zingiber xishuangbannaense is common in primary tropical monsoon forest, from 500 to 1450 m. It also occurs as a weed on the edge of disturbed sites, such as rubber plantations. Based on information provided on herbarium labels, in Thailand and Laos this species grows in deciduous and seasonal evergreen hardwood forests, pine forest, or bamboo forest, on granite bedrock or lime stone area. Flowering commences in mid-August and extends to mid-October. Fruiting commences in mid-October and extends to December.

Additional specimens examined:— CHINA. Yunnan Province: Pu’er City : Yunxian Xiang, Tuanshan, 26August 1984, Anonymous 231 ( HITBC) ; Jiangcheng Xian, Hongjiang Xiang, Niuke River , 29 October 1989, Y. Y. Qian 2055 ( HITBC). Lincang City, Menglian Xian, Mengma Xiang, Meng’a, 12 August 1973, Anonymous 010072 ( HITBC) ; Lingcang City, Menglian Xian, Mengma Xiang , Xishan , 14 August 1977, Menglian Expedition 10184 ( HITBC). Cangyuan Xian, Banlao Xiang, 31 October 1989, G. D.Tao & X. W.Li 43032 ( IBSC). Xishuangbanna, Mengla Xian, Manzhuang, 29 October 1983, Expedition 23826 ( HITBC) ; Mengla Xian, Bubeng Natural Reserve , elev. 800 m, 13 November 1982, Expedition 34046 ( HITBC) ; Mengla Xian, Yaoqu Xiang , elev. 1450 m, 21 November 1982, S. Q. Tong 32907 ( HITBC) ; Jinghong city, Mengyang Zhen, Dahebian , 12 August 1982, S. Q. Tong & Y. T. Liu 249369 ( HITBC) ; Jinghong city, Mengyuan Zhen, Nanping , elev. 900 m, 10 September 2005, S. S. Zhou 2877 ( HITBC) . LAOS. Sainyabuli Province: Phiang District, hill west of Nambouy Village , J. F. Maxwell 99-270 ( CMU) . Khammouane Province: Tham Mot Ngam , elev. 549 m, 6 November 2005, M. F. Thomas et al. LAO940 ( E) . Luang Prabang Province: K.Phoutthavong & K. Souvannakhoummane KP 452 (image of flowering material seen only) . THAILAND. Chiang Rai Province: Mae Sai, Doi Dtung (Tung), Buddhist shrine neat Wat Pra That Doi Dtung (Temple), Huay Krai Subdistrict , 29 October 2005, P. Palee 863 ( CMU) ; ibidem, 5 November 2004, J. F. Maxwell 04-671 ( CMU) . Chiang Mai Province: Doi Chiang Dao, SE, foothills near Ban Yang Pong Luang, elev. 600 m, 30 September 1989, J. F. Maxwell 89-1166 ( E) ; ibidem, 11 November 1996, J. F. Maxwell 96-1527 ( BKF) ; Mae Ai District , Tad Mok Fall, Anonymous 009-6 ( CMU) .

Lampang Province: Mueang Pan District, Chae Son National Park, 24 August 1996, J. F. Maxwell 98-1122 ( BKF). Nam Province : Evergreen forest along stream, Sapan Waterfall , elev. 600 m, 7 September 1995, K.Larsen et al. 46180 ( BKF). Nakhon Phanom Province: Ban Phaeng, Phu Langka National Park , Tad Kham Falls R.Pooma et al. 2648 ( BKF) ; ibidem, R. Pooma et al. 7283 ( BKF). Phetchabun Province: Nam Nao District, Nam Nao National Park , elev. 850 m, 11 October 1979, T.Shimizu et al. 18256 ( BKF, duplicate in KYO). Sakon-Nakhon Province: Phu-Phan, September 1987, P.Yuktathat 145 ( E) ; Phu Phan National Park, Pha Nang Moen, 31 July 1999, M. F. Newman 949 ( E, BKF). Nakhon Ratchasima Province: east part of Khao Yai National Park , elev. 400 m, 11 August 1968, K.Larsen et al. 3318 ( BKF, E), Khao Yai National Park , elev. 800 m, October 7, 1962, T.Smitinand 7515 ( BKF). Nakhon Nayok Province: Muang, Khao Yai National Park , 22 November 1999, R. S.Chongko 32 ( BKF). Kanchanaburi Province: Huay Bankau, 10 November 1971, 750 m, C. F.Beusekom et al. 3663 ( BKF, E) .

Notes: — Zingiber xishuangbannaense was described based on a collection from Xishuangbanna, Yunnan Province, in southwestern China ( Tong & Xia 1987). This locality is approximately 1000 km north of the type locality of Z. thorelii (southern Laos). Triboun et al. (2007) treated Z. xishuangbannaense as conspecific with Z. thorelii and consequently regarded all populations from Thailand as Z. thorelii , stating that in Thailand Z. thorelii varied greatly in the following characters (see also Triboun 2006) inflorescence shape (obclavate with appressed imbricate bracts, widest at base and narrowing to an attenuate or obtuse at apex, 8–14 × 2.5–3.5 cm); 2) flower size (no measurements given); and 3) bract colour (green, pale pink to bright red). The treatment of Z. xishuangbannaense as conspecific with Z. thorelii is, however, somewhat surprising given that Z. thorelii is morphologically much closer to Z. oligophyllum than to Z. xishuangbannaense ( Fig. 7 B–D ). The relationship between Z. oligophyllum and Z. thorelii was not discussed by Triboun et al. (2007).

A study of herbarium specimens from China and southeast Asia, as well as living flowering material from the type localities (or nearby areas) of Z. xishuangbannaense and Z. thorelii reveals that even though the colour and number of bracts is variable in both species, the bract arrangement enables them to be reliably distinguished. Zingiber xishuangbannaense has densely compacted bracts with the rachis never visible even in late flowering stage, whereas Z. thorelii has loosely arranged bracts with the rachis often visible (or at least easily accessible by simply spreading the bracts).Also, as indicated above, Z. xishuangbannaense occurs in southwestern China (Yunnan Province only), northern Laos and Thailand, whereas Z. thorelii is so far known only from southern Laos and southern Vietnam. Therefore, based on morphological differences supported by geographical distribution we have resurrected Z. xishuangbannaense as a distinct species.

We have examined more than 60 specimens from Thailand belonging to the “ Z. oligophyllum complex” (BK, BKF and CMU) and found that more than half belong to Z. xishuangbannaense . Excluding sterile specimens which cannot be confidently assigned to a species, the remaining ca. 26 Thailand collections (mainly from northern, northeastern and southern Thailand) likely belong to a yet undescribed taxon that is characterized by the following combination of characters: laminas densely villous abaxially, bracts tightly arranged and completely obscuring the rachis (thus differing from Z. thorelii ), the upper part of bracts being tapered, free and not appressed to the bracts positioned above them (thus differing from Z. xishuangbannaense ). As we have not seen living flowering material of this entity, the description of this taxon (which probably represents a new species) is not pursued in this paper and requires further field studies. Although so far we have not seen any specimens indicating that Zingiber thorelii occurs in Thailand, it is likely that the species might be recorded in the future from eastern Thailand due to proximity to the type locality in Laos.

A full description of this species based on our collections from near the type locality is provided above, and a colour plate is provided in Figure 9 .

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 7. Distribution of Zingiber oligophyllum (purple), Z. thorelii (yellow), Z. ventricosum (red), and Z. xishuangbannaense (blue). Type localities of the four species are marked with stars. Distribution records are based on study of herbarium material, living material and photographic records.

FIGURE 9. Zingiber xishuangbannaense S.Q.Tong A. Habit. B. Pseudostem (plants growing in fully exposed area). C. Pseudostem (plants growing in densely shaded area). D–F. Inflorescences (note variable colour of the bracts). G. Single flower (side view with bracteole). H. Dissection (from left): bract, bracteole, calyx, dorsal corolla lobe, two lateral corolla lobes, labellum with lateral staminodes basally connate, apical part of floral tube with stamen and style, ovary with two epigynous glands. Based on living collections from type locality, Xishuangbanna, Yunnan Province, China. Photos: Lin Bai.