Dendrobium wenshanense Q.Xu, Y.B.Luo & Z.J.Liu, 2014

Xu, Qing, Zhang, Guo-Qiang, Liu, Zhong-Jian & Luo, Yi-Bo, 2014, Two new species of Dendrobium (Orchidaceae: Epidendroideae) from China: evidence from morphology and DNA, Phytotaxa 174 (3), pp. 129-143 : 137-139

Dendrobium wenshanense Q.Xu, Y.B.Luo & Z.J.Liu , sp.nov. (Ž山石ª; Figs. 4 , 5 )

Type:— China. Yunnan (云南): Malipo (fi栗坡), epiphytic on tree trunks in forests, 1500 m, 12 December 2013, Liu 7283 (holotype: NOCC!) .

Diagnosis: this new species is similar to Dendrobium wilsonii , but differs in having: a dorsal sepal that is 4.4–4.5 cm long and narrowly ovate-oblong; petals that are 4.5–4.6 × 1.0– 1.1 cm and obovate-oblong; and a lip that is 3.1–3.3 × 1.8–1.9 cm and subobovate. The lip is entire, 1.0–1.1 × 4.0– 4.5 cm with oblong callus at base. The surface of the callus is covered with dense short hairs. It is also similar to D. fanjingshanense , but differs in having: flowers that are white and larger with yellowish green plaque at the base of the lip; a dorsal sepal that is 4.4–4.5 cm long; lateral sepals that are 4.5–5.0 cm long; a lip that is 3.1–3.3 cm long; and a column foot that is 1.0– 1.2 cm long. The petals are 4.5–4.6 cm long and obovate-oblong.

Epiphytic herbs. Stems ascending, narrowly cylindric, 17–45 cm long, and 3–5 mm in diameter, unbranched, with internodes 1.5–3.4 cm long. Leaves alternate on upper part of stem, oblong, 3.5–6.1 × 0.8–1.4 cm, apex unequally bilobed, base with clasping sheath. Racemes 1 or 2, arising from upper part of old leafless stems, 1–2-flowered; peduncle 5–7 mm long; floral bracts ovate-lanceolate, 5–7 mm long, membranous. Pedicel and ovary 2.5–3.0 cm long. Flowers white, spreading, with a yellowish green plaque at base of lip. Dorsal sepal narrowly ovate-oblong, 4.4–4.5 × 1.0– 1.1 cm, apex acute; lateral sepals obliquely lanceolate, 4.5–5.0 × 4.4– 1.2 cm, apex acute; mentum subglobose, 1.0– 1.2 cm long. Petals obovate-oblong, 4.5–4.6 × 1.0– 1.1 cm, apex acute; lip subobovate, 3.1–3.3 × 1.8–1.9 cm, entire, apex acute, with an oblong callus at base, 1.0–1.1 × 4.0– 4.5 cm, callus surface densely covered by short hairs. Column 3–4 mm long with a foot 1.0– 1.2 cm long; anther cap subglobose, densely finely papillate; pollinia 4, obovate, in 2 pairs.

Flowering period: —February to March.

Distribution and habitat: — Dendrobium wenshanense is epiphytic on tree trunks in forests at 1500 m in Malipo, Yunnan Province, China. Etymology: —The species epithet refers to the locality where this new species was first found. Conservation status: —Using the World Conservation Union Red List Categories and Criteria ( IUCN, 2001), D. wenshanense should be treated as critically endangered.

Species recognition: — Dendrobium wenshanense is distinct among species in the genus because it has: large, white flowers with a yellowish green plaque at the base of the lip; a narrowly ovate-oblong dorsal sepal, 4.4–4.5 cm long; lateral sepals 4.5–5.0 cm long; obovate-oblong petals 4.5–4.6 × 1.0– 1.1 cm; and a subobovate lip 3.1–3.3 × 1.8– 1.9 cm. The lip is entire with an acute apex and an oblong callus at the base. The callus is 1.0–1.1 × 4.0– 4.5 cm with dense short hairs. The column foot is 1.0– 1.2 cm long and similar to that of D. wilsonii , but can be easily distinguished from the latter, which has: oblong-lanceolate dorsal sepal that is 2.5–4.0 cm long; subelliptic petals that are 2.5–4.0 ×1.0– 1.5 cm; and an ovate-lanceolate lip. The lip is shorter and wider than the sepals and trilobed or inconspicuously trilobed, with a callus in the centre of the cuneate base. It is also similar to D. fanjingshanense , but it can be easily distinguished from the latter, which has: a golden yellow flower with purple striate at the base of the lip; a dorsal sepal that is 2.4–2.6 cm long; lateral sepals which are shorter than the dorsal; broadly elliptic or ovate petals, 1.4–2.2 × 1.1–1.7 cm; and a lip that is 1.7–2.1 × 2.1–2.2 cm, with a column foot that is about 3 mm long.

Figures

FIGURE 4. Dendrobium wenshanense Q.Xu, Y.B.Luo & Z.J.Liu. A. Flowering plant. B. Flower, front view. C. Flower, side view. D. Dorsal sepal, petal, lateral sepal and lip. E. Pollinarium.

FIGURE 5. Dendrobium wenshanense. A. Flowering plant. B. Flower, front view. C. Flower, side view. D. Column. E. Pollinarium. F.A flower of D. wilsonii.