Thrixspermum taeniophyllum Jun Y.Zhang, H.He & Yue H.Cheng, 2023

Zhang, Jun-Yi, Cheng, Yue-Hong, Liao, Min, Liu, Gui-Ying, Yang, Pan-Yan, Xu, Bo & He, Hai, 2023, Thrixspermum taeniophyllum (Orchidaceae, Epidendroideae), a new species from southwest China, based on molecular and morphological evidence, PhytoKeys 230, pp. 145-156 : 145

Thrixspermum taeniophyllum Jun Y.Zhang, H.He & Yue H.Cheng sp. nov.

Figs 1A , 3

Type.

China. Sichuan Province, Wenchuan County, Wolong Town , in coniferous and broadleaf mixed forest, on tree trunks, elev. ca. 1762 m, in flower, 30 March 2022, Jun-Yi Zhang, Min Liao & Yue-Hong Cheng ZJY144 (holotype CDBI!) .

Diagnosis.

It is most similar to Thrixspermum japonicum in morphology, but it differs from the latter by its often-branched stems (vs. unbranched stems), slightly fleshy strap-shaped leaves 5-7 cm long (vs. thinly leathery oblong leaves 2-4 cm long), longer inflorescences with 3-6 flowers (vs. shorter inflorescences with 2-3 flowers) and its capitate gynandrium with a lip-shaped mouth opening (vs. conical gynandrium with a triangular mouth opening). It also resembles T. saruwatarii and T. pygmaeum and morphological comparison amongst the four species is visualised in Fig. 1 and summarised in Table 1 .

Description.

Epiphytic on tree trunks. Roots vermiform and slender. Stems ascending or pendulous especially when in flowering, 4-8 cm long, ca. 1.5 mm thick, often branched, internodes 5-8 mm apart. Leaves green, dichotomously alternate, slightly fleshy, strap-shaped, 5-7 × 0.5-1 cm, apex acute and bifid with two unequally mucronate tips. Inflorescence arising from basal stem laterally or opposite to leaves, usually pendulous, 6-12 cm long; rachis slightly flexuous and slightly thickened distally, 4-6 cm long, laxly 3-6 flowered; bracts spirally arranged, obliquely patent, ca. 3 mm long, broadly ovate-triangular, apex acute. Flowers initially white and later turning creamy yellow, blossoming almost simultaneously; dorsal and lateral sepals similar, elliptic, 5-7 × 3.5-4.5 mm, apex obtuse, with obscure 3 veins; petals narrowly elliptic, smaller than sepals, 4.5-6 × 2-3 mm, apex obtuse, with obscure 1 or 2 veins; labellum small, three-lobed, base shallowly saccate; lateral lobes erect, triangularly oblong, ca. 2.5 mm, apex rounded or ± notched, inner surface with many purplish-red stripes; mid-lobe fleshy, reddish-brown, very small, apex ended with triangular teeth; disc concave, inside base densely covered with red purple or golden yellow hairs; gynandrium capitate, with a lip-shaped mouth opening; ca. 2.5 mm high; column foot ca. 1.2 mm, with one joint at the junction with the labellum; pollinia 4 grouped into two nearly similar masses, ca. 0.8 × 0.7 mm, yellow, full and obovately spherical. Fruits unseen.

Distribution and habitat.

Thrixspermum taeniophyllum was found in Wenchuan County, Sichuan Province, southwest China. It is epiphytic on trees in coniferous and broadleaf mixed forest at an elevational range between 1260 and 1770 m.

Phenology.

Flowering in March and April.

Etymology.

The specific epithet taeniophyllum is a compound adjective referring to the shape of leaves of this new species. A Chinese name, dai ye bai dian lan (带叶白点兰), is also suggested, based on the its leaf feature.

Additional specimens examined.

China. Sichuan Province, Wenchuan County, Wolong Town , evergreen broad-leaved forest, on tree trunks, elev. ca. 1769 m, in flower, 1 May 2023, Jun-Yi Zhang & Yue-Hong Cheng ZJY189 (CDBI!) ; Sichuan Province, Wenchuan County, Gengda Town , evergreen broad-leaved forest, on tree trunks, elev. ca. 1508 m, in flower, 2 May 2023, Jun-Yi Zhang & Yue-Hong Cheng ZJY191 (CDBI!) ; Sichuan Province, Wenchuan County, Gengda Town , evergreen broad-leaved forest, on tree trunks, elev. ca. 1520 m, in flower, 2 May 2023, Jun-Yi Zhang & Yue-Hong Cheng ZJY192 (CDBI!) .

Examined specimens of Thrixspermum japonicum .

Japan. P. F. V. Siebold, s.n. (holotype L; It is not clear whether duplicates exist); China. Sichuan, Emeishan, elev. ca. 990 m, 12 July 1980, K. Y. Lang, B. C. Gao et al. 044 (PE); Baoxing, elev. ca. 1800 m, 2 April 1983, D. Y. Peng 47469 (CDBI!); Beichuan, elev. ca. 1640 m, 1 August 1984, C. L. Tang et al. 284 (CDBI!). Chongqing: Nanchuan, elev. ca. 900 m, 2 November 1983, Z. Y. Liu 4669 (IMC); Nanchuan, elev. ca. 850 m, 30 May 1984, Z. Y. Liu 5219 (PE).

Examined specimens of Thrixspermum saruwatarii .

China. Taiwan, Alishan, 8 April 1916, B. Hayata, s.n. (holotype TI); Kaohsiung, 20 October 1934, S. Sasaki, s.n. (TAI). Yunnan, Gongshan, elev. ca. 1702 m, 20 May 2007, X. H. Jin 9001 (PE). Hunan, Ningyuan, elev. ca. 340 m, 8 May 2011, X. L. Yu 11050801 (CSFI). Guangdong, Dapu, elev. ca. 700 m, 9 June 1957, L. Deng 4953 (IBSC).

Examined specimens of Thrixspermum pygmaeum .

China. Taiwan, Taipingshan, 3 April 1940, Y. Kobayashi, s.n. (TI); Taitung, 22 March 1932, S. Sasaki, s.n. (TAI); Miaoli, 13 November 1972, C. C. Hsu 12600 (TAI); Ilan, 10 March 2013, C. C. Hsu, s.n. (TAI).

Figures

Figure 1. Comparison of four species of Thrixspermum. Living plant of T. taeniophyllum (A), T. japonicum (B), T. saruwatarii (C) and T. pygmaeum (D); Detailed colour photos of T. japonicum (E: a habit b leaves c inflorescence d, e flower in front and back view f 1 dorsal sepal f 2 - 3 petals f 4 - 5 sepals f 6, h labellum g gynandrium and ovary i anther cap); Type specimens of T. taeniophyllum (F: holotype at CDBI), T. japonicum (G: holotype at L) and T. saruwatarii (H: holotype at TI); and a representative specimen of T. pygmaeum (I: TI). [Images A and E photographed by Min Liao; image B photographed by Yue-Hong Cheng; image C cited from website (https: // kevinyu 589. blogspot. com /) image D cited from website (https: // www. gbif. org / species / 2846707); the image of the type specimen of T. japonicum was obtained from JSTOR and those of T. saruwatarii and T. pygmaeum were cited from available from Plants of Taiwan (https: // tai 2. ntu. edu. tw / search / 2)].

Figure 3. Thrixspermum taeniophyllum A flowering plant B leaves C inflorescence D part of the rachis showing persistent bracts E flower in front view F dissection of a flower (F 1: dorsal sepal; F 2 - F 3: petals; F 4 - F 5: sepals; F 6: labellum) G, H labellum I pollinia J gynandrium and ovary.