Bulbophyllum nghiasonii, 2021

Dang, Minh Quan, Averyanov, Leonid V., Dang, Van Son, Bui, Van Huong, Amsler, Roland, Maisak, Tatiana & Truong, Ba Vuong, 2021, A new miniature species, Bulbophyllum nghiasonii, sect. Brachyantha (Orchidaceae) from northern Vietnam, Phytotaxa 505 (2), pp. 235-239 : 236-238

Bulbophyllum sect. Brachyantha Rchb. f.

B. nghiasonii Vuong, Aver. & V.S.Dang , sp. nov. ( Fig. 1 )

Type: — VIETNAM, herbarium prepared from cultivated plant in July 2009 by L. Averyanov, T. Maisak, HAL 12681c.1 originated from Phu Tho Province, Tan Son District , Xuan Son Municipality , Du Village , around point 21°06’57”N 104°57’17”E, 16 Feb. 2009, L. Averyanov , P. K. Loc , N. T. Vin , L. T. Son (Holotype, LE 01055793 ! http://en.herbariumle.ru/?t=occ&id=7690 LE 01087158 ! http:// en.herbariumle.ru/?t=occ&id=18682) .

Paratypes: — VIETNAM, Thanh Hoa Province, Quan Son District, Son Ha Commune, Ban Ha Village , forest around Tai Stream , 19 April 2020, Truong Ba Vuong, Dang Van Son, Bui Van Huong, Dang Minh Quan, BV 616 ( VNM00024324 !) . VIETNAM, herbarium prepared from cultivated plants in 30 May 2020, Truong Ba Vuong, Dang Van Son, BV 740 ( VNM00024325 !) originated from Thanh Hoa Province, Quan Son District, Son Ha Commune, Ban Ha Village , forest around Tai Stream . VIETNAM, herbarium prepared from cultivated plants in 18 January 2021, Truong Ba Vuong, Dang Van Son, BV 1019 ( VNM00024329 !) originated from Thanh Hoa Province, Quan Son District, Son Ha Commune, Ban Ha Village , forest around Tai Stream .

Etymology:—The species is named after Prof. Hoang Nghia Son, the director of the Institute of Tropical Biology ( Vietnam Academy of Science and Technology), who established and supported VNM Herbarium as the significant center for studies of the plant taxonomy.

Description:— Miniature clustering branch epiphyte. Pseudobulbs ovoid, oblique, 6 mm long, 5 mm in diameter connected by stout rhizome, covered by brownish sheaths. Leaves somewhat fleshy, elliptic to broadly elliptic, 20–22 mm long, 8–10 mm wide, apex slightly apiculate or acute, margin finely erose at apical part; adaxially green, abaxially light green, finely papillose; petiole ca. 1.5 mm long, slightly twisted near the base, articulated with pseudobulb. Inflorescence arising from the base of pseudobulb, bearing 2 to 3 flowers opening simultaneously; peduncle erect, ca. 3.5 mm, slightly curved, pale yellowish orange, covered by 3 brownish overlapping sheaths; rachis slender, ca. 7 mm long; floral bracts narrowly triangular, attenuate, ca. 1.5–2 mm long, 0.8–1 mm wide; pedicel and ovary 3–3.5 mm long, pedicel curved. Flowers not widely opening, dorsal sepal orange to pale orange, lateral sepals orange to bright orange-red, petals white, lip orange to pale orange. Dorsal sepal with 3 veins, broadly ovate, ca. 3 mm long, 2 mm wide, apex blunt. Lateral sepals oblong narrowly ovate, 4–4.2 mm long, 1–1.5 mm wide, oblique, apex blunt, upper margin revolute inward and connate in apical part becoming free during anthesis, lower margin connate in basal half. Petals with 3 veins, semi-circular, oblique, 8 mm long, 5 mm wide, apex rounded. Lip ligulate, simple, entire, ca. 2 mm long, 1 mm wide, adnate to column foot with white thin appendage, slightly curved and grooved, abaxially with 2 low keels, apex blunt to almost rounded. Column short, ca. 1 mm tall, at front with broadly triangular lateral wings; column foot ca. 1.1 mm long, strongly up-curved; stelidia slender, acute, ca. 0.8 mm long, slightly pointing forward or downward; stigma rectangular, lower margin of stigma with 2 small rounded calli; rostellum white, half-circular, distally rounded, slightly forward protruding; anther cap orange, helmet shaped, ca. 0.5 mm in diameter, finely rugose; pollinia 4, unequally ovoid. Capsule not seen.

Habitat and Phenology:—Clustering epiphyte on small mossy trees in primary broad-leaved closed wet forest on very steep rocky slopes and cliffs of low remnant mountains composed with highly eroded solid marble-like limestone at elevation 400–500 m a.s.l. Flowers in April–July, and December.

Distribution:— Vietnam (Thanh Hoa and Phu Tho provinces). Endemic.

Proposed conservation status:—According to available observations the new species is rare. More field studies are needed for assessment of its true conservation status. According to the IUCN criteria ( IUCN, 2019) it may be tentatively assessed at present as “Data Deficient” (DD).

Additional specimens studied: — INDIA, Uttarakhand State Tehri Garhwal District “Western Himalaya, Tehu-Garhwal District, about 30 miles E. of Tehu, Mackinnon, P. W. 25402 ” (photos: K000829982 !, K000829983 !, K000829984 !), as Cirrhopetalum hookeri ( Duthie 1902: 38) . INDIA, photo made in 4August 2013 from plant originated from India and cultivated in Switzerland, Amsler 295, under the name C. hookeri ( Fig. 2 ) ; JAPAN, Kagoshima province, Kyushu, 21 May 1968, Furuse F., 39892 (Photo: L0624949 !), as B. japonicum

Notes:—The newly described species looks similar to B. muscicola and B. japonicum , but differs in habit and shape of sepals, petals, and lip. The morphological comparison of B. nghiasonii and the related species is presented on the Table 1. Cirrhopetalum hookeri and C. wallichii are considered as synonyms of B. muscicola ( Averyanov, 2012) .

Figures

FIGURE 1. Bulbophyllum nghiasonii. A. Flowering plants; B. Leaf apex and portion of leaf abaxial surface with high magnification. C. Inflorescences. D. Flowers, frontal and side views. E. Flower bract. F. Intact flower, frontal and side view. G. Dorsal sepal. H. Lateral sepals. I. Petals. J. Lip views from different sides. K. Pedicel, ovary and column, side view, sepals and lip removed. L. Pedicel, ovary and column, side view. M. Column, frontal and half side views. N. Anther cap, views from different sides. O. Pollinia. Photos by Truong Ba Vuong, correction and design by L. Averyanov and T. Maisak.

FIGURE 2. Bulbophyllum muscicola. Photo by R. Amsler of plant (Amsler 295) originated from India and cultivated under that name Cirrhopetalum hookeri.