Dendrobium zhenghuoense S.P. Chen, L. Ma & M.H. Li, 2016

Chen, Shi-Pin, Ma, Liang, Lan, Si-Ren & Li, Ming-He, 2016, Morphological and molecular evidence for a new species from China: Dendrobium zhenghuoense (Epidendroideae; Orchidaceae), Phytotaxa 275 (3), pp. 277-286 : 285

Dendrobium zhenghuoense S.P. Chen, L. Ma & M.H. Li sp. nov. (úffihfi, Figs. 2 , 3 )

Type:— China. Fujian (AEû): Zhenghe (úffi), epiphytic on tree trunks in forests, alt. 950 m, 1 May 2016, Li Minghe 20160501 (holotype, FAFU).

Diagnosis: This new species is characterized by possessing short stems with 2 to 3 nodes, 1-flowered inflorescence borne from the upper nodes of older leafless stems, yellowish-green flowers with reddish-green plaque at the front of lip, and a long pedicel and mentum. The new species is similar to D. hekouense and D. luoi , but can be distinguished by the size of stem and mentum, shorter peduncle, and increased length of pedicel, ovary, and lip.

Epiphytic herb; plants short, ca. 4.0 cm. Rhizome ca. 1.5 mm in diameter, abbreviated, prostrate. Stems clustered, golden-yellow when dry, stout, ovate-elliptic, 0.8–1.2 cm long, up to 0.5 cm wide, 2- to 3-noded; internodes 0.2–0.4 cm long, somewhat swollen, each covered with a membranous yellowish-white sheath; young stems sheathed at the basal nodes, 2- to 3-leaved, tender; old stems leafless. Leaves obovate-elliptic or narrowly lanceolate, 1.2–3.5 cm × 2.0– 3.5 mm, apex usually unequally bilobed, sheaths amplexicaul. Inflorescences 1-flowered, borne from the upper nodes of older leafless stems; peduncle 2.5–5.5 mm long, 1-noded, with a broadly ovate, acuminate bract; basal sheaths 2 or 3, membranous. Pedicel and ovary 2.4–2.8 cm long. Flowers, fragrant, thick, yellowish-green with a reddish-green plaque at the front of the lip. Dorsal sepals ovate, 8.5–9.0 × 3.5–4.5 mm, apex acuminate; lateral sepals obliquely ovate, 0.9–1.0 × 0.6–0.7 cm, apex acuminate; mentum ca. 1.2–1.4 × 0.6–0.8 cm, apex rounded. Petals oblong-lanceolate, ca. 8.5–9.5 × 3.0–4.0 mm, apex acuminate; lip elliptic-ovate to flabellate, 2.2–2.4 × 0.8–0.9 cm, adaxial surface with curly hairs in center above the middle, margin undulate. Column ca. 2.0 mm long with a foot 1.2–1.3 cm long; anther cap subglobose; pollinia 4, in 2 pairs.

Phenology: —Flowering April to May.

Distribution and habitat: –– Dendrobium zhenghuoense is epiphytic on conifers in a coniferous and broad-leaved mixed forest at 950 m in Zhenghe County, Fujian Province, China.

Etymology: —The specific epithet refers to the only locality where this new species has been found thus far.

Conservation status: ––The new species was found in only two populations, each of which consisted of no more than 40 individuals. Using the World Conservation Union Red List Categories and Criteria ( IUCN, 2012), D. zhenghuoense should be treated as critically endangered. We have not given the precise locality of D. zhenghuoens as we are concerned that the beautiful species may be the target of illegal collection.

Taxonomic notes: — Dendrobium zhenghuoense is very distinctive among Dendrobium species. It is morphologically similar to D. luoi , but can be distinguished by its yellowish-green flowers; shorter peduncle (2.5–5.5 mm vs. 7.0–9.0 mm); longer lip (2.3–2.4 cm vs. 1.7–1.8 cm), longer pedicel & ovary (2.4 –2.8 cm vs. 2.0– 2.5 cm), and mentum size (1.2–1.4 × 0.6–0.8 cm vs. 1.0–1.2 × 0.4–0.5 cm) ( Table 3).

Figures

FIGURE 2. Dendrobium zhenghuoense S.P. Chen, L. Ma & M.H. Li.A. Habit.B. Flower, ventral view. C. Flower, side view. D. Pollinium. E. Dorsal sepal, petal, lateral sepal, and lip (clockwise). F. Lip and column, longitudinal section. Drawn by Zheng-Meng Yang.

FIGURE 3. Dendrobium zhenghuoense S.P. Chen, L. Ma & M.H. Li. A. Flowering plant. B. Flower, side view. C. Flower, front view. D. Anatomy of the flower.