Chamaeanthus averyanovii Vuong, Kumar, V.H. Bui, V.S.Dang, 2021

Pham, Phuoc Dien, Kumar, Pankaj, Dang, Van Son, Nguyen, Dinh Hiep, Bui, Van Huong, Tu, Bao Ngan, Dang, Minh Quan & Truong, Ba Vuong, 2021, Notes on the genus Chamaeanthus (Orchidaceae, Epidendroideae, Vandeae, Aeridinae) with a new species from Vietnam, Phytotaxa 524 (2), pp. 131-134 : 132

Chamaeanthus averyanovii Vuong, Kumar, V.H. Bui, V.S.Dang , sp. nov. ( Fig. 1 )

Type:— VIETNAM. Son La Province: Thuan Chau District, 18 June 2021, Truong Ba Vuong , Bui Van Huong, BV 1194 ( VNM 00069908 !)

Etymology:—The specific epithet honors Prof. Leonid Averyanov for his outstanding contribution to the orchid science in Asia.

Description. Miniature clustered epiphyte. Stem ca. 5 mm long, covered with distichous leaf sheaths. Leaves fleshy, oblong, slightly concave and falcate, 3–4 cm long, 5–7 mm wide, acute, unequally 2-lobed at the apex, sheathed at the base, sheaths ca. 7 mm long embracing the stem. Inflorescence spike, arising from lower leafless part of the plant, glabrous; peduncle green, terete, 6–7 mm long, with 1 to 4 distantly bracts; rachis clavate, ca. 11 mm long; flowers up to 15, with 1–3 flowers blooming at the same time, not open widely; floral bract green, concave, narrowly triangular, ca. 2 mm long, acuminate; pedicel with ovary faintly greenish-white, glabrous, ca. 2 mm long, terete; tepals white, sub-similar, pale yellow towards the apex, lip white, pale yellow at the base. Dorsal sepal narrowly elliptic, 5–5.5 mm long, 1.5 mm wide, tapering to caudate at the apex; lateral sepals narrowly elliptic, 5.5–6 mm long, 1.5 mm wide, tapering at the apex. Petals narrowly elliptic, 4.5–5 mm long, 1 mm wide, tapering at the apex. Lip 3-lobed, spur absent, glabrous, conical in outline shaped, attached to column foot by a small appendage; midlobe conical, ca. 2.5–3 mm long, entire, apex pugioniform; side lobes erect, rectangular, ca. 1.2 mm long, 1 mm wide, margin irregularly dentate. Column ca. 1 mm long, lower margin with triangular wing; column foot as long as or slightly longer than ovary, oblique, ca. 1.1 mm long; anther cap helmet shape, ca. 1mm long; pollinia 2, subglobose. Fruit not seen.

Habitat and phenology:—Epiphytic on small tree branches on canopy. Flowering in June to July.

Distribution:— Vietnam (Son La Province), endemic

Additional specimens studied: MALAYSIA:— Chamaeanthus brachystachys August 190, R. Schlechter s.n. (Isosyntype, AMES00106675)

Notes:— C. averyanovii looks similar to C. brachystachys and C. canhii , however, they are different. The comparative account is presented in Table 1 .

Morphological data of C. brachystachys is based on Schlechter (1905) and Pridgeon et al. (2014): t. 636.1 by Judi Stone, from KEW spirit collection: Borneo, 1989 A. Lamb AL1154/89 (number 56439)

Figures

FIGURE 1. Chamaeanthus averyanovii Vuong, Kumar, V.H. Bui, V.S.Dang: A & B. Plant habit; C. Leaf apex; D. Leaf sheath; E. Inflorescence; F. Flower; G. Floral bract; H. Dorsal sepal; I. Lateral sepals; J. Petals; K. Lip; L. Column and column foot; M. Stigma; N. Anher cap; O. Pollinia. All photo by Truong Ba Vuong from specimen BV 1194.