Anoectochilus formosanus Hayata, Icon. Pl. Formosan.

Anoectochilus formosanus Hayata, Icon. Pl. Formosan. View in CoL 4: 101. 1914. Type: TAIWAN (without precise locality), from cultivation in Taihoku, 03.1914, B. Hayata s.n. (not found). Anoectochilus tetsuoi Ohwi ex Hatus. & T. Amano, Fl. Okinawa 148. 1958, nom. nud. FigS. 1 View Fig & 2 View Fig

Vernacular names: Taiwan jewel orchid; wan yin xian lan in Mandarin); wan gam sin lin in Cantonese); ( kibana-shusuran in Japanese).

Plants erect, up to 25 cm tall. Rhizomes creeping, ascending, terete, 0.3–0.5 cm diam., bearing thick hairy roots. Leaves 2–5, clustered at the base of the plant; petioles 1.5–2.5 × 0.8–1 cm, bright reddish-brown, sheathing at base; lamina ovate, 2–5 × 2– 3.5 cm, acute at apex, margins pale white, reddishgreen dorsally, dark green with silver-white markings ventrally. Peduncles erect, terete, slender, up to 3-noded, hairy, pale reddish-brown, up to 20 cm long, bearing 2–3 sterile bracts; sterile bracts ovate, 1–1.5 × 0.8–1 cm, acute at apex, membranous, bright red-brown. Floral rachis 3– 5.5 cm long, bearing up to 7 laxly arranged flowers; floral bracts ovate, 1–1.5 × 0.6–0.8 mm, acuminate at apex, hairy on the dorsal surface, glabrous ventrally, reddish-brown. Flowers resupinate, sepals and petals greenish-brown to greenish-red, labellum white flushed yellow on the outer surface of the mesochile and along the flanges, the spur flushed green; pedicel and ovary 12–16 × 3–5 mm, covered with glandular hairs; dorsal sepal broadly elliptic, 6–6.5 × 4.3–4.5 mm, tapering at both ends, acuminate at apex, forming a hood with the petals above the column, hairy with glandular hairs on dorsal surface, glabrous ventrally; lateral sepals obliquely ovate, 7.5–8 × 4–4.5 mm, acute, hairy with glandular hairs on dorsal surface, glabrous ventrally, semi-transparent to whitish along the lower margins; petals obliquely ovate, appressed to the margins of the dorsal sepal, 6–7 × 3–3.5 mm, acuminate and Y-shaped, hooked at the apex, apical margins slightly revolute, glabrous, semi-transparent; labellum spreading and projecting downwards, adnate to the base of the column, 17– 19 × 12–14 mm including the spur, 3-partite; hypochile flabellate when flattened, 2.5–3 × 1.5–2 mm, lateral margins rolled upwards, terminating in a pair of short, ovate-triangular auricles; mesochile canaliculate, 4.5–5 × 3–4 mm, margins raised, flanged on either side, each flange somewhat fleshy and divided into up to 8 teeth, each tooth 0.2–5.5 mm long; epichile 2-lobed, lobes narrowly elliptic, diverging, 8–9 × 2.5–3 mm, obtuse; spur conical, 2.5–3 × 2.4–2.6 mm, pointing backwards, conspicuously longitudinally channeled along the external surface, with one oblong callus (on either side) attached to the inner wall, callus up to 2 mm long, attached only at the centre. Column ovoid, 2–3 × c. 2 mm. Pollinarium Y-shaped, c. 3.5 × 2 mm; lobes obovate, arched inwards, 2–2.5 mm long; caudicle bifurcated into two elliptic lobes, c. 2.5 mm long; viscidium longitudinally 2-lobed, 1– 1.5 mm long, larger lobe obovate, shorter lobe obovate to sagittate. Anther-cap 2-lobed; lobes obovate, 2.6–2.8 × 2.2–2.5 mm, semi-transparent, yellow, beaked at the front, lobes held together by a semi-circular disc at the top; disc 2–2.2 × 2.6–2.7 mm, base cordate, margins minutely erose.

Flowering: Flowering from October to November.

Habitat: Grows in leaf detritus on mossy boulders, close to streams in mature montane forest.

Distribution: China ( Hong Kong only), Japan (Ryukyu Islands) and Taiwan (central mountains and Lanyu Island). The determinations of many specimens held at TAIF and PE are doubtful, and specimens are missing from several sheets; these vouchers are therefore omitted from the list of specimens examined below. Refish et al. (2015) cited one dubious record for Mainland China ( Fujian Province), although the species was not listed by either Chen et al. (2009) or Zhou et al. (2016). Similarly, Ket et al. (2004) record the species in Vietnam (Lamdong Province), although it is not listed in any recent enumerations of the orchid flora of Vietnam (Averyanov & Averyanova, 2003; Govaerts et al., 2020).

Specimens examined: CHINA, Hong Kong, New Territories, Tai Po, 12.11.2019, P . Kumar 12215 ( KFBG) . JAPAN, Okinawa Prefecuture, Ishigaki-jima, Omoto-dake, 27.11.1957, T . Amano 7736 ( RYU); Ibid . , 27.12.2003, M . Yokota s.n. ( RYU); Ishigaki-jima , Fukaiomoto-dake, 24.12.2016, M . Yokota s.n. ( RYU); Iriomote-jima , Goza-dake, 17.08.1966, Y . Miyagi 3566 ( RYU); Okinawa-jima, Iyu-dake , 24.11.2013, M . Yokota s.n. ( RYU) . TAIWAN, Hualien County, Yanhai log road, 19.08.1988, S . Y . Lu 23797 ( TAIF); Changchun Temple , 13.12.2006, S . W . Chung & C . W . Lin 9187 ( TAIF) ; Hualien Hsien, 150–400 m, 26.01.1989, C . I . Peng 12343 ( HAST!); Tatung Tribe , 800–1000 m, 03.12.2011, T . C . Hsu 5138 ( TAIF) . Hsinchu County, Hsinchu Nanzhuang, 01.09.1914, S . Sasaki s.n. ( TAIF) ; Keelung, Nuannuan, Dandan, 27.11.1938, G . Masamune 3743 ( TAI); Mt. Chungcheng , 06.11.2006, T . C . Hsu 644 ( TAIF); Mt. Kaopu , 300–400 m, 01.11.2011, T . C . Hsu 4937 ( TAIF) ; Pingtung, Tachienshihshan, 20.10.1990, T . C . Huang, S . F . Huang & M . J . Wu 14890 ( TAI) ; Shuli County, Mt. Taiheizan , 28.07.1928, S . Suzuki 1125 ( PE); Wufong , 700–800 m, 02.10.2014, T . C . Hsu 7339 ( TAIF) . Taipei City, Chihtanshan, 22.10.1933, I . Simozawa 1126 ( TAI); 825 m, 19.10.1992, C . C . Liao 751 ( HAST); Chingshan nursery, 600 m, 03.11.1997, K . C . Yang & W . L . Chiou s.n. ( TAIF); Chulushan, Tiirokuzan, 900 m, 06.11.2010, s.coll. s.n. ( TAI); Yunshen Water Fall , 500 m, 20.10.2011, s.coll. s.n. ( TAI) . Taitung County, Lichia Logging Trail, 06.10.2014, H . C . Hung 489 ( TAIF); Mt. Kueina , 27.11.2008, T . C . Hsu 2038 ( TAIF); Mt. Tulan , 700–900 m, 23.11.2011, T . C . Hsu 5109 ( TAIF) .

Conservation status: Anoectochilus formosanus was originally described from Taiwan ( Hayata , 1914; Chen et al., 2009) and subsequently found in the southern Ryukyu Islands of Japan (Garay & Sweet, 1974; Iwatsuki et al., 2016). More recently, it has been discovered on Okinawa Island and here we add Hong Kong in continental East Asia to the species’ range. It is difficult to estimate population size for Taiwan (where it occurs throughout the central mountains) and Japan (where it is known from Ishigaki, Iriomote and Okinawa islands), since data are lacking. The Hong Kong population comprises a single site known to the authors, although local orchid enthusiasts have claimed the occurrence of more individuals elsewhere. Despite being reported from China ( Refish et al., 2015) and Vietnam ( Ket et al., 2004), the species was not included by either Chen et al. (2009) or Zhou et al. (2016) in their accounts of Chinese Orchidaceae , and Leonid Averyanov (pers. comm.), a leading expert on the flora of Vietnam, doubts its occurrence in Vietnam. Like A. roxburghii , A. formosanus is collected for its purported medicinal and ornamental value (Garay & Sweet, 1974; Shiau et al., 2002; Barretto et al., 2011) and is thereby threatened with local extinction. Indeed, the single known population on Okinawa Island has been entirely extirpated by collectors (M. Yokota, pers. comm.). Excluding the doubtful mainland Chinese and Vietnamese records, the species’ Extent of Occurrence (EOO) and Area of Occupancy (AOO) are calculated as 229,846 km 2 and 192 km 2 respectively, using 2 × 2 km grid in GeoCAT ( Moat, 2007). The latter may qualify the species for a status of Endangered under Criterion B, but we infer the occurrence of more than 40 sites and there is no evidence to suggest these populations are severely fragmented, or that the species has undergone extreme fluctuation in any population parameter. However, given the ongoing threat of collection, and both observed and projected decline in the species’ EOO, AOO, number of subpopulations and number of mature individuals, we consider the species to be Near Threatened following IUCN guidelines ( IUCN, 2019).

Notes: Anoectochilus formosanus is easily distinguished from A. roxburghii on account of its dark green leaves with silvery-white venation, resupinate flowers and yellowish labellum with fleshy flanges, short spur ( 2.5–3 mm long) with oblong calli and rounded spur-apex; in contrast, the latter has brownish leaves with golden venation, erect, double-resupinate flowers and a white labellum with filamentous flanges, long ( 9–14 mm long) spur with warty calli and bilobed spur-apex. However, when dried and pressed as herbarium specimens, the leaves of both species tend to turn black or brown and the mesochile flanges of both shrink and become filamentous, making it very difficult to differentiate the two. We searched for the type specimen among the material deposited in the Taiwanese herbaria but without success, and it is apparently not to be found at TI either (T. Yukawa, pers. comm.). There may therefore be a need to neotypify. However, because more effort should first be put into locating the holotype, or into selecting a suitable neotype in the event that the holotype is confirmed as lost, we refrain from doing so here.