Zingiber chengii Y.H.Tseng, C.M.Wang, & Y.C.Lin, 2020

Wang, Chiu-Mei, Lin, Yuan-Chien & Tseng, Yen-Hsueh, 2020, Zingiber chengii (Zingiberaceae), a new species from Taiwan, PhytoKeys 139, pp. 1-11 : 1

Zingiber chengii Y.H.Tseng, C.M.Wang, & Y.C.Lin sp. nov. Figs 1 , 2 , 3 , 4 , 5

Diagnosis.

Zingiber chengii sp. nov. is morphologically similar to its Taiwanese congeners. However, the new species can be distinguished from them by its deciduous leafy shoots while those of Z. kawagoii , Z. oligophyllum and Z. shuanglongense are evergreen; Z. chengii has narrow lanceolate to linear leaves, whereas Z. kawagoi and Z. shuanglongense have ovate to lanceolate ones; except Z. oligophyllum , which has yellow flowers, all native species of Taiwan have reddish-purple flowers; each spike of Z. chengii bears 1-3 flowers, whereas spikes of Z. kawagoi and Z. shuanglongense bear 8-11 and 4-10 flowers, respectively; Zingiber chengii rarely has sterile bracts, whereas Z. kawagoii and Z. shuanglongense have apparent sterile bracts; Zingiber chengii has ovoid fruit, whereas Z. kawagoii and Z. shuanglongense has ellipsoidal one. Both Z. kawagoii and Z. shuanglongense are almost enveloped by the aril, whereas Z. chengii is one-third enveloped by the aril (Table 1 ).

Compared with the images of the syntype of Z. pleiostachyum , Z. chengii has much narrower lamina, with a length: width ratio of ca. 6 (vs. ca. 3.8 in Z. pleiostachyum ) and rarely has sterile bracts. Zingiber chengii is similar to Z. tenuifolium L. Bai endemic to Yunnan ( Bai et al. 2015b), but the number of blades per leafy shoot of Z. chengii is about 11-15 vs. 13-23 in Z. tenuifolium . The two species can also be distinguished by the length to width ratio of the lamina, which is ca. 6 in Z. chengii vs. ca. 10 in Z. tenuifolium . Zingiber tenuifolium also has apparent sterile bracts while these are rare in Z. chengii . These comparisons indicate that Z. chengii is clearly different from other known similar congeners, therefore we treat Z. chengii as a new species in Taiwan. Also, Z. chengii has ellipsoidal pollen grains with spiro-striate sculpturing (Fig. 5 ), and the inflorescence borne on a radical, procumbent peduncle (Fig. 1A , 2E , 3F ). These characters indicate that this new species belongs to sect. Cryptanthium .

Type.

TAIWAN. Hsinchu County, Jianshih township, elevation ca. 320 m, 23 May 2014. Yen Hsueh Tseng 5614 (Holotype: TCF).

Description.

Perennial rhizomatous herbs, 40-70 cm tall. Rhizomes fleshy, compacted, sympodial, densely branched, 0.8-1.4 cm in diameter, surface brown, center light yellow; root tubers terete, distantly from the rhizomes, ca. 3.8 × 1.2 cm, surface brownish green. Leafy shoots erect, 1-16 per plant, forming dense clumps, spreading, each shoot comprising 11-15 well-developed leaves at anthesis. Leaves deciduous, simple, distichous; ligules ca. 2 mm long, bilobed, membranaceous, pale green, auriculate; petiole 2.0-3.0 mm long, adnate to lamina by a pulvinus; lamina linear-lanceolate to lanceolate, 9-15 × 1.5-2.5 cm, length:width ratio 5.1-6.6, adaxial surface green, glabrous, abaxial surface pale green, pubescent along the midrib, base cuneate obtuse, apex acuminate, margin entire, conspicuously undulate, chartaceous. Spike 1-2 per plant, arising from rhizomes; peduncles 2.5-6.2 cm long, ascending, glabrous; spike narrowly oblong, ca. 10.5-12.5 × 2.0-3.0 cm, each with 1-3 flowers; fertile bracts yellowish green, one-flowered, lanceolate, 2.5-3.0 × 0.6-0.8 cm, usually red tinged, usually involute on both sides, apex acute to attenuate; bracteole lanceolate, 1.8-2.8 × 0.6-0.8 cm, translucent green with slight red tinge, apex acute. Flowers ca. 7.0-9.0 cm long, exerting much beyond the bracts; calyx tubular, membranaceous, ca. 7 mm long, with unilateral incision, translucent. Corolla tube slender, ca. 3.5-cm long, cream-white, glabrous externally and internally; dorsal corolla lobe lanceolate, ca. 2.7 × 0.7 cm, purple, apex acuminate; lateral corolla lobes lanceolate, ca. 2.5 × 0.7 cm, purple, apex acuminate; labellum widely obovate, ca. 3.0 × 2.5 cm, purple, apex retuse or entire, scattered with cream-white patches at base; lateral staminodes narrowly oblong, ca. 2.0 × 0.5 cm, connate to labellum at ca. basal 1/3 to 1/4, purple. Stamen one; filament short; anther connective tissue cream-white, elongated appendage of a wrapped style; anther thecae two, ca. 1 cm long, longitudinal dehiscense, pollen light yellow; anther crest beak-shaped, ca. 1.5-cm long when stretched, purple, apex entire. Style filiform, white, ca. 5.5-cm long, extending to the end of anther crest; stigma white, ciliate. Ovary cylindrical, trilocular, ca. 6.0 × 3.0 mm, yellowish green, glabrous; epigynous glands two, narrowly conical, ca. 6-mm long, pale yellow, apices sharp. Capsule ovate, dehiscence loculicidally ca. 1.5 × 1.3 cm, usually as long as the persistent bract, pericarp yellowish cream or orange-red inside. Seed ellipsoid, ca. 4.0 mm × 2.0 mm, enveloped by the aril. Aril white, deep denticulate at apex, enveloping 1/3rd of the length of the seeds. Pollen grains ellipsoidal, 103.16-112.01 × 68.73-81.73 μm with P/E ratio 1.32-1.56, surface inaperturate and with spiro-striate sculpturing (Fig. 5 ).

Phenology.

Flowering between May and July, and fruiting between July and September. Growth and reproduction period between March and September, withering from September to November, and dormant period between December and February (Fig. 2 ).

Distribution and habitat.

Endemic species of Taiwan. Based on the geographical climatic regions and vegetation zones ( Su 1984, 1985), Z. chengii is distributed only in the northwest inland region, moist areas of cloud forests of the Machilus - Castanopsis forest zone at an altitude of 530 m, and is found only on the rock cliff of Yuluo riverside (Hsinchu County) in northern Taiwan (Fig. 4 ). Common companion species are Arundo formosana Hack. ( Poaceae ), Sedum actinocarpum Yamam. ( Crassulaceae ), Rhaphidophora hongkongensis Schott ( Araceae ), Pothos chinensis (Raf.) Merr. ( Araceae ), Pilea plataniflora C.H.Wright ( Urticaceae ), and Pyrrosia lingua (Thunb.) Farw. ( Polypodiaceae ). Sometimes, Z. kawagoii is found nearby; however, no potential hybrid individual has been observed.

Chinese name.

Hsia-yeh-chiang (狹葉薑).

Etymology.

The species epithet " chengii " was given in honor of Mr. Yuen-Chun Cheng (鄭元春) who first discovered the new species.

Conservation status.

Zingiber chengii has been abundant on the rock cliff of Youluo riverside, where more than 100 individuals have been observed in an area of ca. 400 m2, since 2014. However, its population gradually decreased due to disturbances by visitors. Additional specimens were discovered along the Yuluo riverside in similar riverine habitats. These areas are difficult to approach due to the presence of hazardous rivers and cliffs. We categorize the new species as Endangered (EN B1; C2a(i)) following IUCN (2017).

Additional specimens examined.

Zingiber chengii : TAIWAN. Hsinchu County, Hengshan Township (24.694, 121.184), 23 May 2014. Yen Hsueh Tseng 5615 (TCF); same loc., 29 May 2017. Chao 4471 (TAIF); same loc., 25 July 2014. Chiu-Mei Wang & Ching-Yao Li 16051 (TNM); same loc., 7 June 2015. Y.C. Lin 1148 (TCF); Bilin Bridge (24.695, 121.220), 1 July 2015. Y.C. Lin 1355 (TCF).

Zingiber shuanglongense : TAIWAN. Nantou County, Sinyi Township, Shuanglung Logging Trail, Y.C.Lin 1294 (TCF); Jenlun Logging Road, Y.C.Lin 1306 (TCF); Chiayi County, Jhuci Township, Mt. Dadungshan backbend (huitouwan), Y.C.Lin 1292 (TCF); Kaohsiung City, Taoyuan District, Tengchih, Y.C.Lin 1256 (TCF); Jiasian District, Mt. Paiyun, Y.C.Lin 1319 (TCF).

Zingiber kawagoii : TAIWAN. New Taipei City, Shiding District, Mt. Erhkeshan, Y.C.Lin 1066 (TCF); Nantou County, Jiji Township, Mt. Chichidashan, Y.C. Lin 1290 (TCF); Chiayi County, Alishan Township, Lungtou, Y.C. Lin 1278 (TCF), Mihu trail, Y.C.Lin 1151 (TCF); Kaohsiung City, Maolin District, Shanping, Y.C. Lin 985 (TCF); Pingtung County, Shizi Township, Shuangliu Forest Recreation Area, Y.C. Lin 1303 (TCF).

Zingiber pleiostachyum : TAIWAN. Syntype: Pingtung County, Bankinsing mountains, A. Henry 147 (K & UPS) & 1659 (K).

Identification key to the species of Zingiber in Taiwan

Figures

Figure 1. Line drawings of Zingiber chengii Y. H. Tseng, C. M. Wang & Y. C. Lin, sp. nov. A habit B base of plant C rhizome D-E leaf adaxial and abaxial surface F ligulate G-K bracts and bracteoles L dorsal corolla lobe M lateral corolla lobe N-O inflorescences P flower Q pistil R stamen and anther crest S labellum with basally connate lateral staminodes T fruit.

Figure 2. Phenologic phases of Zingiber chengii Y. H. Tseng, C. M. Wang & Y. C. Lin, sp. nov. A withering period B dormant period (rhizome) C growth period D mature period E flowering period.

Figure 3. Zingiber chengii Y. H. Tseng, C. M. Wang & Y. C. Lin, sp. nov. A habit B rhizome C the cross-section of rhizome D leaf blade E ligule and sheath (side view) E ' sheath (front view) F inflorescence G flower dissection 1 fertile bracts 2 Bracteole 3 calyx 4 dorsal corolla lobe 5 lateral corolla lobes 6 Labellum with basally connate lateral staminodes 7 ovary 8 floral tube with stamen and stigma (side view) H-J fruit K seeds.

Figure 4. Distribution map of Zingiber chengii Y. H. Tseng, C. M. Wang & Y. C. Lin, sp. nov.

Figure 5. Pollen morphology of Zingiber chengii Y. H. Tseng, C. M. Wang & Y. C. Lin, sp. nov. A equatorial view B polar view.