Gastrodia albidoides Y. H.Tan & T. C.Hsu, 2012

Tan, Yun-Hong, Hsu, Tian-Chuan, Pan, Bo, Li, Jian-Wu & Liu, Qiang, 2012, Gastrodia albidoides (Orchidaceae: Epidendroideae), a new species from Yunnan, China, Phytotaxa 66 (1), pp. 38-42 : 38-41

Gastrodia albidoides Y. H.Tan & T. C.Hsu , sp. nov. ( Fig. 1–2 )

Species G. theanae et G. albidae affinis, sed perianthii tubo non manifestum longitudinaliter striato et verrucoso, lateralibus sepalis 1/2 longitudine connatis e basi, petalis aequalis non verruculoso, columnae pede et rostello conspicuo differt.

Type:— CHINA. Yunnan: Mengla, Xishuangbanna National Nature Reserve , in tropical rainforest, 700–800 m, 12 May 2012, Tan 6809 (holotype: HITBC!) .

Terrestrial, leafless, achlorophyllous herbs. Roots few, slender, 1–13 cm long, ca. 0.5–0.7 mm in diameter. Rhizome fleshy, tuberous, fusiform, 20–50 mm long, 5–12 mm in diameter, grayish brown, finely irregularly verrucose, scaly. Scales verticillate, oblong-lanceolate, brownish black, ca. 2 mm long. Inflorescence erect, terminal, 1.0– 8.5 cm long, ca. 3 mm in diameter, white to pale whitish, peduncle 1–4 noded; sheath membranous, ovate to broadly ovate, 3–5 × 2–3 mm; rachis often less than 5 mm long. Bracts membranous,

holotype.

ovate to ovate-oblong, apex pointed, pale yellowish-brown, 3.0–5.0 × 2.0– 2.5 mm. Ovary 3–7 mm long, 1.5–3.5 mm in diameter. Flowers (1–)2–5(–8), erect, bell-shaped, slightly curved, not opening widely, 9–11 mm long, 5–7 mm in diameter. Tepals united, forming a 5–lobed tube, 9–11 mm long, slightly verrucose apically, otherwise smooth. Sepals similar, fleshy, thickened, lateral sepals fused to ½ their length, whitish, apex with sparse pale yellowish spots; free lobe of dorsal sepal broadly ovate, ca. 1.5–2.0 × 3.0– 3.5 mm; free lobes of lateral sepals ovate, ca. 1.5 × 2.0 mm, each bearing a pale yellowish thickened callus inside. Petals whitish on both sides, unthickened, fleshy, thin, triangular-ovate, 0.8–1.0 × 0.6–0.8 mm. Lip free from perianth tube, adnate to column foot, pale-green tinged yellow at base and reddish-brown apically and marginally, 3.5–4.5 ×2.0– 2.5 mm; hypochile with two whitish, globose, subsessile, nectarless calli, ca. 1 mm in diameter; epichile rhombate-ovate, 6–7 nerved, rounded at base, entire, disc thickened and distinctly 2- ridged in the middle, ridges much raised and tinged yellowish near apex. Column white, straight, 4.0–4.5 × 1.5–1.8 mm, base with short foot, apex with a pair of lateral wings; lateral wings with acuminate tips superior to anther; rostellum well developed, 0.2 × 1.5 mm; stigma located near base. Anther hemispherical, 0.6–0.7 mm in diameter; pollinia 2. Capsule ellipsoid, 1.5–2.0 cm long, 0.5–0.8 cm in diameter; pedicel elongating to 8–20 cm long in fruit. Seeds fusiform, 1.6–2.2 mm long.

Distribution and habitat:— Gastrodia albidoides is currently found in southern Yunnan, China. The only population found so far occurs in a tropical rainforest in the Xishuangbanna National Nature Reserve, Mengla County.

Phenology:— Flowering mainly in May and fruiting from May to early June.

Relationships:— Gastrodia albidoides is most similar to G. theana Averyanov (2005: 90) from Vietnam and G. albida Hsu & Kuo (2011: 272) from Taiwan. They share dwarf habits, whitish and scarcely opening flowers, curved and fleshy perianth tubes and similar columns and lips. After comparison of available literature and specimens, we are concluded that G. albidoides could be clearly differentiated from G. theana and G. albida by several floral characters ( Table 1).

Figures

FIGURE 1. Gastrodia albidoides (from the type locality). A. Longitudinal section of flower. B, C. Column. D. Lip, column, and ovary. E–G. Flowering individual. F. Fruiting individual. Photographs by Yun-Hong Tan.

FIGURE 2. Gastrodia albidoides. A. Habit. B. Lateral view of flower. C. Ventral view of flower. D. Flattened perianth tube. E, F. Lip, column and ovary. G. Column. H. Anther cap and rostellum. I. Lip. J. Fruiting specimen. Illustration by Yun-Xi Zhu, based on the