Anoectochilus zhongshanensis C.J.Zheng & Y.B.Wu, 2023

Wu, Yan-Bin, Han, Yu, He, Xu-Hui, Chen, Hui-Ling, Wu, Jin-Zhong, Ye, Qi & Zheng, Cheng-Jian, 2023, Anoectochilus zhongshanensis (Orchidaceae), a new species from Guangxi, China, PhytoKeys 234, pp. 203-218 : 203

Anoectochilus zhongshanensis C.J.Zheng & Y.B.Wu sp. nov.

Figs 3 , 7

Type.

China. Guangxi province: Zhongshan County, Hezhou City, under evergreen broad-leaved forest or shady and humid valleys, cultivated at the Medicinal Botanical Garden of the Second Military Medical University , 12 August 2020, Wu20200812003 (holotype: FAFU!) .

Diagnosis.

A. zhongshanensis is similar to A. zhejiangensis , but can be distinguished by the hastate or scalpel-shaped lobes of epichile (vs. semiovoid), forward curved and pinnately divided cristate lobes at both sides of the mesochile (vs. backward curved, the same orientation as the spur), unbowed conical spur (vs. bowed) and inverted triangle column wings (vs. squarish) (Fig. 6 ). A. zhongshanensis is also similar to A. malipoensis , but can be distinguished by the hastate or scalpel-shaped lobes of epichile (vs. obovate lobes with acuminate apex and crenulate margins), pinnately divided cristate lobes at both sides of the mesochile (vs. obliquely subquadrate and serrate lobes) and inverted triangle column wings (vs. elliptic) ( Chen and Shui 2010).

Description.

Terrestrial herb, 8~22 cm tall, with an erect stem and 2~6 leaves. Leaf ovate or orbicular, 1.2-4.0 × 1.0-2.8 cm, adaxially black with fine golden red net veins with silk luster, abaxially purplish red, apex acute, base subtruncate or rounded, abruptly narrowed into a stalk; petiole 4-12 mm long, base enlarged into a cauline sheath. Racemose inflorescence, 1-6 flowered, inflorescence rachis pubescent; peduncle long and slender, mauve red, pubescent, with 2-4 mauve sheath-like bracts; floral bracts reddish, ovate-lanceolate, ca. 6 × 3 mm, apex acuminate, abaxially pubescent, subequal length as the ovary or slightly longer; ovary cylindrical, not twisted, reddish brown, white pubescent, connected with pedicel ca. 13 mm long; flowers not resupinate (labellum held uppermost); sepals reddish, subequal, ca. 5 mm long, abaxially puberulent; dorsal sepal ovate, sunken navicular, apex acute, joined with petals to form a hood; lateral sepals oblong, slightly oblique; petals white greenish, obliquely falcate, ca.5 mm long, middle part ca. 1.5 mm wide, base narrow, apex acute; lip white, upstretched, Y-shaped, 13 mm long, epichile longitudinally dilated, 2-lobed, lobes hastate or scalpel-shaped, 5 mm long, ca. 2 mm wide, apex blunt, diverging at an acute angle; mesochile ca. 4 mm long, flange bearing forward curved and pinnately divided cristate lobes at both sides; conical spur, ca. 10 mm long, obliquely upward, subvertical to ovary, apex shallowly bilobed, containing 2 subcuneate calli. Column ca. 4 mm long, ventrally with an inverted triangular column wing on both sides. Anther cap ovate, ca. 3 mm. Pollinia 2, yellow, obliquely clavate, ca. 3 mm long. Rostellum erect, apical concave and bifurcated. Stigma lobes 2, distinct, located to the sides of the rostellum. Fruit not seen.

Etymology.

Referring to the locality (Zhongshan County) where this new species was found.

Vernacular name.

钟山金线兰 (Chinese pinyin: zhong shan jin xian lan).

Distribution and habitat.

A. zhongshanensis is currently known only from Zhongshan County, Hezhou City, Guangxi Province, China. This species grows in evergreen broad-leaved forests or shady and humid valleys, elev. 500-1200 m.

Conservation status.

During our three surveys in April, August and September 2020, Anoectochilus zhongshanensis was found in the forests or shady and humid valleys of Zhongshan County only at two separate locations, where we counted fewer than 100 individuals at each site. Due to the highly medicinal and edible value of Anoectochilus plants ( Ye et al. 2017; Wu et al. 2022a; Shi et al. 2023), over exploitation and collection remains a high-risk factor for continuing resource decline and thus the major threat to these species, especially those with restricted distribution and small population size. All Anoectochilus plants have already been listed as potentially endangered species in the 'List of National Key Protected Wild Plants in China’ (Level II) issued on Sep 7, 2021 by the National Forestry and Grassland Administration, and Ministry of Agriculture and Rural Affairs of the People’s Republic of China (http://www.gov.cn/zhengce/2021-09/07/content_5727413.htm). Though the comprehensive population assessment of A. zhongshanensis in the whole Zhongshan County has not been conducted, conservation status of this new species is best classified as ‘Endangered’ (En) (IUCN guidelines 2020) based on the discovered small population size of less than 200 mature individuals and potential risk of continuing decline in the number of mature individuals.

Phenology.

Flowering in August-October.

Figures

Figure 3. Anoectochilus zhongshanensis A 1 and A 2 habit B flower (front view) C flower (lateral view) D sepals and petals E spur F anther cap G pollinia H column (front view) I column (lateral view) J column (rear view). Photographs by Yan-Bin Wu.

Figure 6. Diagnostic morphologic characteristics comparing A. zhongshanensis (A-D), A. zhejiangensis (E-H) and A. malipoensis (I-L) A, E, I flower (front view) B, F, J flower (lateral view) C, G, K column (front view) D, H, L column (lateral view). Photographs by Yan-Bin Wu.

Figure 7. Anoectochilus zhongshanensis A habit B leaves C flower (front view and lateral view) D ovary (cross section) E sepals F petals G spur H core column (front view, lateral view and rear view) I anther cap and pollinia. Drawn by Li-Xiang Zheng.