Platanthera guangdongensis Y.F. Li, L.F. Wu & L.J. Chen, 2018

Platanthera guangdongensis Y.F. Li, L.F. Wu & L.J. Chen View in CoL sp. nov. (ỮṪǺḆĔ; Figs. 4 View FIGURE 4 , 5 View FIGURE 5 )

Type:— CHINA, Guangdong ( ỮṪ). Zijin ( ẾḮ), in a dense forests near the valley, alt. 660 m, 31 May 2017, Liu 10273 ( holotype: NOCC!).

Diagnosis:— Platanthera guangdongensis is similar to P. fujianensis , from which it differs by the shorter inflorescence and fewer flowers (3.5–5.0 cm with 5–9 flowers vs. 8.0–10.0 cm with 13–18 flowers), shorter floral bract ( 0.6–0.9 cm vs. 1.3 cm), ovate-elliptic dorsal sepal (vs. broadly ovate), oblong lateral sepal (vs. oblong-lanceolate), ovate-elliptic petal (vs. ovate), and ligulate lip (vs. ligulate-triangular).

Herbs terrestrial, leafless, holomycotrophic. Plants 19–22 cm tall. Rootstock cylindric, fleshy, 1.3–2.5 × 2.5–3.5 cm, with many hairy appendages. Stem erect, yellowish green, with 7–8 tubular sheaths at base; sheaths 1.0–1.5 × 0.2–0.5 cm. Inflorescence racemose, 3.5–5.0 cm long, with 5–9 flowers loosely arranged; floral bracts lanceolate, 0.6–0.9 cm long, apex acute. Sepals and petals pale greenish, lip pale greenish yellow, spur pale greenish white; pedicel and ovary 1.0– 1.2 cm long. Dorsal sepal erect, ovate-elliptic, 2.1–2.5 × 1.4–1.6 mm, apex obtuse; lateral sepals oblong, oblique, 4.0–4.5 × 0.9–1.2 mm, apex obtuse. Petals ovate-elliptic, oblique, 3.2–3.6 × 1.1–1.3 mm, apex obtuse; lip ligulate, 4.0–4.3 × 1.4–1.6 mm, apex obtuse; spur pendulous, cylindric, 1.0– 1.2 cm long. Column ca. 2.0 mm; pollinia obovoid, with slender caudicles and suborbicular viscidia; stigma concave, lying directly below rostellum.

Phenology: —Flowering May.

Distribution and habitat: –– Platanthera guangdongensis is only known from Zijin country, Guangdong Province, China. It grows in a dense forest, which is mainly composed of Alpinia densibracteata ( Zingiberaceae ), Altingia chinensis ( Altingiaceae ), Ardisia punctata , Myrsine seguinii ( Myrsinaceae ), Castanopsis fissa , C. fordii ( Fagaceae ), Dalbergia millettii , Millettia dielsiana ( Fabaceae ), Ehretia longiflora ( Ehretiaceae ), Itea chinensis ( Iteaceae ), Gordonia axillaris ( Theaceae ), Rhododendron championiae ( Ericaceae ), and Woodwardia japonica ( Blechnaceae ). Other orchids, Apostasia shenzhenica , Cymbidium ensifolium , Lecanorchis nigricans , Tainia dunnii , were found growing nearby this new species.

Etymology: —The specific epithet refers to the locality of Guangdong Province where this new species has been found.

Conservation status: ––The new species was found in only two populations, each of which consisted of no more than 10 individuals. Using the World Conservation Union Red List Categories and Criteria ( IUCN, 2016), P. guangdongensis should be treated as critically endangered.