Bulbophyllum section Epipphium (Blume, 1825) Schlechter, 1913

Nguyen, Van Tu, Averyanov, Leonid V., Dang, Van Son, Maisak, Tatiana V., Bui, Van Huong, Dang, Minh Quan, Boo, Sung Min & Truong, Ba Vuong, 2022, A new species of Bulbophyllum from Northern of Vietnam, Phytotaxa 542 (1), pp. 95-99 : 96

Bulbophyllum section Epipphium

Bulbophyllum xuandangii Vuong, Aver. & V.S. Dang sp. nov. Figure 1

Type:— VIETNAM, Son La province, Thuan Chau district, Bon Phang commune, forest of Nam Tien village , 8 July 2019, Truong Ba Vuong , Bui Van Huong, BV 363 ( VNM 00069937 )

Etymology:—The species name after Mr. Bùi Xuân Ðáng, the Vietnamese orchid enthusiast.

Description:—Miniature branch or small trunk epiphyte orchid. Pseudobulb with one leaf, green to dark green, ovoid to sub-globose, 6 – 8 mm in diam., with many irregular wrinkled, growing close together or separated 5 – 6 mm on woody, stout, creeping rhizome. Leaves oblong to broadly elliptic, green to dark green above, greenish below, 28 – 35 mm long, 1 – 1.6 mm wide, slightly curved at apical part, apex acute to sub-acute; petiole sessile or subsessile. Scape from base of pseudobulbs, slender, filiform, erect, 30 – 31 mm long, base with 2 to 3 brown overlapping tubular bracts, with or without above tubular bract ca. 3 mm long; rachis ca. 2 mm long, subumbellate, carry 3 – 5 flowers; floral bract pale brown with green line in middle, 2.5 – 3 mm long, apex acute or long acute; pedicel (with ovary) pedicel slender, curved orang, ovary orangish-green. Flowers opening in same time, dorsal sepal, petals and lip red, lateral sepals yellow, orange at base. Dorsal sepal ovate to broadly ovate, concave, 4 – 6 mm long, 2 – 3 mm wide, apex acuminate, straight forward or upcurved, margin fimbriate with clavate hairs; lateral sepals ovate to narrowly ovate, 17 – 28 mm long, 20 – 25 mm wide (at base), twisted at base, margin entire or with intermittent short papillose hairs, apex obtuse, lower margin turn inward fused from base to over middle part, upper margin free at base then fuse as long as lower margin, both free at apical part. Petals broadly ovate, oblique, falcate, 3 – 3.2 mm long, 2.3 – 2.5 mm wide, apex acute, margin involute (out curved), fimbriate with few simple hairs mixed with clavate hairs, margin and apical inner surface papillose. Lip simple, slightly outcurved, narrowly ovate in outline shape, apex sub-acute, connected with column foot by thin ligament; abaxial shallowly channeled at base, 2 lateral ridge from base below middle, covered by densely ciliate hairs; abaxial with 2 keels forming a groove. Column ca. 2 mm long, lower margin with unclear triangular wing;, foot ca. 3.5 mm long, apical upcurved; stelidia slender, subulate, straight forward or slightly falcate ca. 1 mm long, upper margin with triangular tooth; stigma with broadly pyriform opening, lower margin with 2 rounded keel extended to mid of column foot; anther cap helmet shape, with yellow papillose callus in middle, lower margin fimbriate; pollina 4, obovate, concave at base. Fruit not seen.

Habitat and phenology: —The species was found growing as epiphyte on short tree trunks towards the apex and small branches, in primary broad-leaved forest on granite. Flowering in July (BV 363) February (BV 1094)

Proposed conservation status:—The species is spread in the area with eight subpopulations.There is eminent threat of poaching and plants are collected rigorously for trade at the local market. Hence, each subpopulation is considered a unique location, constituting and EOO of 43.7 km 2 and AOO of 32 km 2. There is abundance of suitable habitat available for this species and the plants are often observed to set fruits naturally resulting in successful regeneration. Based on given information the species can be assessed as Vulnerable, however, with habitat availability more subpopulations are expected in the area, hence, the species is assessed as Near Threatened NT B1ab(iii)+B2ab(iii).

Studied specimen (paratype):— VIETNAM, Son La province, Thuan Chau district, Chieng Bom commune, forest of Chieng Bom , 21 February 2021, Truong Ba Vuong, Bui Van Huong, BV 1094 ( VNM 00069938 )

Taxonomic notes:—Owing to colour of flower, presence of hairs at the base of lip B. xuandangii looks similar to B. yongtaiense , B. sridithii and B. layae , the morphological comparison of similar species is presented in the Table 1 .

Figures

FIGURE 1. Bulbophyllum xuandangii. A, Flowering plant; B. Inflorescence; C. Floral bract; D. Flower; E. Dorsal sepal and papillose surface; F. Lateral sepals; G. Petals and margin; H. Lip; I. Column; J. Keels on column; K. Stigma; L. Stelidia. (Photo by Truong Ba Vuong)