Coelogyne sondangii Vuong, Aver. & V.H.Bui, 2022

Vo, Doan Trung, Averyanov, Leonid V., Maisak, Tatiana V., Bui, Van Huong, Nguyen, Van Canh, Dang, Minh Quan, Nguyen, Quoc Bao & Truong, Ba Vuong, 2022, New species, Coelogyne sondangii (Orchidaceae), and a new national record, C. moi, in Vietnam, Phytotaxa 559 (2), pp. 200-206 : 201-204

Coelogyne sondangii Vuong, Aver. & V.H.Bui sp. nov. ( Fig. 1 )

Type:— VIETNAM. Lai Chau Province, Sin Ho District, Lang Mo Commune, forest around Tu Cua Phin Village , 23 March 2022, Truong Ba Vuong , Bui Van Huong, BV 1357 (holotype VNM 00069946 ) .

Paratypes:— VIETNAM, Lai Chau Province, Sin Ho District, Lang Mo Commune, forest around Tu Cua Phin Village , 23 March 2022, Truong Ba Vuong , Bui Van Huong, BV 1358 ( VNM 00069945 ), BV 1359 ( VNM 00069955 ), BV 1360 ( VNM 00069950 ), BV 1361 ( VNM 00069951 ), BV 1362 ( VNM 00069949 ). Photos of living plants used for preparation of the type specimens: — LE01123078 https://en.herbariumle.ru/?t=occ&id=132447, LE01123090 https://en.herbariumle.ru/?t=occ&id=134261 ).

Description:— Herb epiphytic. Pseudobulbs 1-leaved, green, densely clustering, narrowly ovoid, 1.7–2 cm long, irregularly longitudinally wrinkled. Leaves petiolate; petiole 4–8 mm long; leaf blade uniformly green, narrowly elliptic to elliptic, 5.5–8.5 cm long, 2–2.5 cm wide, acute. Inflorescence arising from the base of mature pseudobulbs, erect, 3.2–4.3 cm long; peduncle at base covered by 3–5 brown overlapping thin sheaths, above with a single sheath; rachis carry 2-flowered; floral bracts persistent, broadly ovate, pale brown, 1–1.1 cm long, acute to shortly attenuate; pedicel with ovary 1.3–2 cm long, pedicel white, ovary light greenish. Flowers opening simultaneously, pure white, little sweet fragrant. Sepals and petals subsimilar, narrowly oblanceolate. Median sepal 3–3.2 cm long, 5–6 mm wide, apex rounded. Lateral sepals 3.3–3.5 cm long, 4–5 mm wide, midribs keeled abaxially, saccate at base, forming with column foot a small rounded, pointing backward mentum 3 mm long. Petals 2.7–2.8 cm long, 4–5 mm wide, acute. Lip spatulate, distally suddenly broadening, obscurely 3-lobed, 3–3.5 cm long; median lobe almost half-circular, apex emarginate, with a small central mucro, margin irregularly denticulate; side lobes 2–2.5 mm long, 3–3.5 mm wide, oblique, pointing forward, margin irregular denticulate; disk with 3–4 low, obscure keels; base of the lip saccate. Column 3–3.3 cm long, at apex with obliquely ovate, rounded, irregularly denticulate wings; stigma rectangular; 2 mm long, 3 mm wide; rostellum down curved, 2 mm long, 3 mm wide, apex truncate to slightly emarginate; column foot short, ca. 3 mm long; anther cap rectangular, 2 mm long, at apex with a fleshy cordate callus, front margin 2-lobed; pollinia 4, obovoid. Fruit not seen.

Habitat and phenology:—Miniature clustering branch epiphyte. Broad-leaved evergreen submontane forests at elevation about 1200 m a.s.l. Flowers in March.

Distribution:—The species up to now was found only in one location in Lai Chau Province where two colonies on two separate trees were observed. These observations outline species area of occupancy (AOO) as less than 4 km 2. The species collecting for the sale on the local markets leads to obvious decline of mature individuals at the present time. At the same time, the total number of mature individuals cannot be estimated due to clustering character of the species growth. Following to the criteria proposed by IUCN (2019), its conservation status may be assessed as critically endangered – CR B2(a,bv), C2(ai).

Notes:—The new species resembles Coelogyne albiflora , C. demissa , C. distelidia (I.D. Lund 1987: 519) M.W.Chase & Schuit. (2021: 109) , C. panchaseensis , C. sagittata , and C. yunnanensis in white flowers and miniature habits. It differs from C. yunnanensis , C. albiflora , and C. panchaseensis in having lip with distinct side lobes. The new species differs from C. sagittata having 3-lobed lip, in erose-denticulate lip side lobes pointing forward (vs. lip side lobes entire, pointing backward). Coelogyne sondangii also resembles C. distelidia but differs in column wings irregularly denticulate at apex (vs. the margin of column wings entire). From all mentioned species, discovered plant differs in having large flowers with tepals at least twice longer than in any other Vietnamese congeners. The morphological comparison of C. sondangii and similar species is presented in the Table 1 .

Figures

FIGURE 1. Panisea sondangii.A. Flowering plant. B.Apical part of inflorescence. C. Flowers, views from different sides. D. Floral bract, abaxial and adaxial side. E. Median sepal, abaxial and adaxial side. F. Apex of median sepal, abaxial side. G. Lateral sepal, abaxial and adaxial side. H. Petal, abaxial and adaxial side. I. Lip, abaxial, adaxial and side view. J. Lip apex, side view. K. Pedicel, ovary and column, side view. L. Apex of column, views from different sides. M. Anther cap, views from different sides. N. Pollinaria. Photos by Ba Vuong Truong from type specimen BV 1357, photos correction and plate design by Ba Vuong Truong, L. Averyanov, and T. Maisak.