Holopogon pekinensis X. Y. Mu & Bing Liu, 2017

Mu, Xian-Yun, Liu, Bing, Zhu, Yi-Xuan, Tong, Ling, Lin, Qin-Wen & Zhang, Zhi-Xiang, 2017, Holopogon pekinensis (Orchidaceae), a new heteromycotrophic species from Northern China, Phytotaxa 326 (2), pp. 151-155 : 151-154

Holopogon pekinensis X. Y. Mu & Bing Liu , sp. nov.

Type:— CHINA. Beijing. Yanqing District, Yudu Mountain, alt ca. 1000 m, 16 August 2017, Xian-Yun Mu, Ling Tong & Yi-Xuan Zhu 4064 (holotype BJFC!)

Diagnosis:— Haec species nova Holopogoni ussuriensi similis, sed inflorescentiis albo-pubescentibus et floribus viridibus differt.

Plants 18–25 cm tall. Rhizome with many fleshy short and tufted roots. Inflorescence green; peduncle with 2–3 sheaths; sheaths 2–4 cm, white, membranous, uppermost one bractlike; rachis 4–8 cm, 5–20-flowered, with light green papillose-pubescent; floral bracts lanceolate, 6–8 mm, membranous, abaxially sparsely pubescent. Flowers erect, actinomorphic, green, sepals and petals open when flowering; pedicel 4–8 mm, slender, papillose-pubescent; ovary ellipsoid, ca. 5 mm, papillose-pubescent. Sepals suberect, narrowly oblong, 3–4 × 1.0– 1.2 mm, with a prominent midvein, outer surfaces slightly pubescent. Petals 3, with a prominent midvein, without a modified lip, similar, narrowly oblong, 3–4 × 0.8–1.0 mm. Column erect, 2–3 mm including anther; filament relatively short; anther subovoid-oblong, 0.4–0.5 mm; pollinia subelliptic. Figs. 1–2 .

Distribution and habitat:— To date, Holopogon pekinensis is only known from one locality in Yanqing District, Beijing City in Northern China, in deciduous broad-leaved forest at ca. 1000 m elevation.

Phenology:— Flowers in August and fruits in September.

Conservation status:— At present, only 17 individuals are found. Therefore, Holopogon pekinensis should be assigned as “Critically Endangered” [CR B1c(i)+B2a+D] following the IUCN Red List ( IUCN 2012). Considering the heterotrophic feature, it would be necessary to conserve the whole ecosystem when protecting this endangered plant.

Additional specimens examined:— The same locality as the holotype, 20 August, 2017, Bing Liu, Qiang Zhang & Qin-Wen Lin 6150 (PE!).

Holopogon sect. Furcilla (S. C. Chen) X. Y. Mu & Bing Liu , sect. & comb. nov. — Archineottia sect. Furcilla S. C. Chen , in Acta Phytotax. Sin. 17(2): 12, 1979.

Notes:— Because of similar column character in Holopogon and Archineottia S. C. Chen (1979: 12) , the latter is treated as a synonym of Holopogon ( Chen 1997) . Although several morphological characteristics existed between Holopogon and Neottia Guettard (1754: 374) such as clinandrium (absent vs present), rostellum (absent vs present), stigma (terminal vs lateral) and filament (distinct vs indistinct) ( Furuse & Chen 1988), molecular phylogenetic studies implies that their relationship are in questionable and need further clarification ( Jin et al. 2015, Chen et al. 2016, Li et al. 2016). The classification system of Orchidaceae in Flora of China is followed here, and Holopogon and Neottia are treated as separate genus.

Within Holopogon , two sections are divided based on flower morphology, sect. Holopogon whose flowers are actinomorphic without modified lip, and sect. Furcilla whose flowers are zygomorphic flower with bilobed lip. Holopogon pekinensis is the fourth species in sect. Holopogon , and can be differentiated from H. microglottis (Duthie 1900: 42) S. C. Chen (1997: 179) by similar sepals and petals (vs sepals twice as broad as petals). It can be discriminated from H. gaudissartii by green flowers and pubescence (vs red). Holopogon pekinensis is close to H. ussuriensis Komarov & Nevski (1935: 751) in having actinomorphic flowers, similar petals which are as broad as sepals. However, it is clearly distinguishable by its green flowers (vs white) and light green (vs red) pubescence on the inflorescence. To date, the new species is found only in Beijing, China, and this genus is a new record to flora of Beijing. Shanxi and Liaoning provinces in China might have a few individuals based on pictures searched on the internet and personal communication. Considering that petal morphology of individuals mentioned above cannot be clearly observed, their identity need further investigation and confirmation. Holopogon ussuriensis is an endangered species endemic to Russia with only two known localities at seaside area in the south of Primorye Territory ( Vakhrameeva et al. 2014). An identification key to Holopogon is provided here.

Figures

FIGURE 1. Holopogon pekinensis X. Y. Mu & Bing Liu.A, habit; B–C, lateral view of flower; D, front view of flower, E, stigma. Drawn by Ying-Bao Sun.

FIGURE 2. Holopogon pekinensis from type locality. A, habit; B, lateral view of flower; C, front view of flower; D, inflorescence; E, sheaths, rhizome and roots. Photographed by Bing Liu and Qin-Wen Lin.