Platanthera jiuwanshanensis Ying Qin & Yan Liu, 2020

Platanthera jiuwanshanensis Ying Qin & Yan Liu View in CoL , sp. nov. (九万山§唇兰; Figs. 1 View FIGURE 1 & 2 View FIGURE 2 )

Type:— CHINA. Guangxi, Jiuwanshan National Nature Reserve, elev. 1309 m, 25°12’N, 108°40’E, 16 September, 2018, Ying Qin, QY20180916002 (holotype: IBK!, isotypes: IBK!).

Diagnosis:—The new species resembles P. fujianensis , P. guangdongensis , P. minor and P. zijinensis but differs from the former two mainly by its falciform lateral sepals, ligulate-linear lip, cylindrical and curved spur and wider connective, and from the latter two by its moniliform or cylindrical rootstock, longest lip and leafless plant.

Herb, green, leafless, 22–51 cm high. Rootstock fleshy, moniliform or cylindrical, pilose, up to 16 cm long, 6–9 mm in diameter, white to chestnut-brown, with many nodes and wide-triangular sheaths; roots fleshy, cylindrical, pilose, ca. 3.3 cm long, 4.6–5.9 mm in diameter, yellowish-brown or chestnut-brown. Stem erect, with 7–8 sheaths, sheaths 1.4–3.1 cm long; upper sheaths amplexicaul, green, apex acute; basal sheaths tubular, white or green, apex acute to obtuse. Inflorescence racemose, 6.5–15.4 cm long, 6–8-flowered, flowers loosely arranged. Bracts lanceolate, acute, equal or shorter than ovary, 0.8–1.6 cm long, 2.7–5.1 mm wide. Ovary cylindrical, twisted, green, 1.9–2.1 mm in diameter, including pedicel to 1.4–1.6 cm long; dorsal sepal broad-ovate, concave, boat-shaped, connivent with petals forming a hood, green, ca. 6 mm long, ca. 5 mm wide, apex obtuse; lateral sepals falciform, green, reflexed towards ovary, ca. 9.5 mm long, ca. 2.3 mm wide, apex obtuse; petals ovate, oblique, green, ca. 6.5 mm long, ca. 2.9 mm wide, apex acute, broaden near the base; lip ligulate-linear, pale yellow-green, pendulous and reflexed towards ovary, ca. 1.1 cm long, ca. 3.1 mm wide, apex obtuse; spur cylindrical, pale green, curved and pendulous, ca. 1.7 cm long, ca. 1.5 mm in diameter, apex obtuse; column white to pale yellow-green, ca. 3.5 mm tall, ca. 4 mm wide; concave connective ca. 1 mm wide; Pollinaria 2, clavate, granular-farinaceous, each with slender caudicle and circular viscidium, viscidium naked in rostellum arm; staminodes 2, prominent, located on both sides of anther base; rostellum short and wide; stigma oval, concave, lying directly below rostellum. Fruits not seen.

Phenology: —Flowering in September.

Etymology: —The epithet is derived from the type locality Jiuwanshan National Nature Reserve, Guangxi, China.

Distribution and ecology: — Platanthera jiuwanshanensis was discovered only from Jiuwanshan National Nature Reserve, Guangxi, China. The populations are distributed in the subtropical evergreen broad-leaved forest with elevations of 1205 m and 1309 m, and companied by Michelia maudiae Dunn , Rhodoleia championii Hooker , Skimmia arborescens T. Anderson ex Gamble , Euscaphis japonica (Thunberg) Kanitz , Dendrobenthamia angustata (Chun) W. P. Fang , Dendropanax proteus (Champion ex Bentham) Bentham , Melliodendron xylocarpum Handel- Mazzetti, Phyllagathis cavaleriei (H. Léveillé & Vaniot) Guillaumin , Aeschynanthus buxifolius Hemsley , Goodyera schlechtendaliana H. G. Reichenbach , Chimonobambusa angustifolia C. D. Chu & C. S. Chao , etc.

Conservation status: —Following the IUCN Red List Categories and Criteria ( IUCN, 2017), P. jiuwanshanensis is assessed as data deficient (DD). At present, after the field investigation, two populations of the species has been found with 8 flowering individuals. However, since the field investigation is not thorough, these data are not enough to evaluate the current conservation status of this new species.

Taxonomic notes: — Platanthera jiuwanshanensis is similar to P. fujianensis and P. guangdongensis in its leafless stem, lanceolate bracts. At the same time, the new species also close to P. minor and P. zijinensis in its boat-shaped dorsal sepal, cylindrical spur, wide connective, reflexed lip. However, P. jiuwanshanensis can be clearly distinguished from them by several characters ( Table 1).

Additional specimens examined (paratype): — CHINA. Guangxi, Jiuwanshan National Nature Reserve, elev. 1205 m, 25°09’N, 108°47’E, 3 September, 2019, Ying Qin, QY20190903001 (IBK!).