Bulbophyllum papilluliferum Vuong, Aver. & Q.T.Truong, 2024

Dang, Minh Quan, Averyanov, Leonid V., Maisak, Tatiana V., Tran, Thi Thuy Nhan, Nguyen, Van Canh, Wook, Um Sung, Nguyen, Quoc Bao, Truong, Quang Tam & Truong, Ba Vuong, 2024, Bulbophyllum section Macrocaulia (Orchidaceae) in Vietnam, Phytotaxa 677 (3), pp. 265-277 : 272-274

6. Bulbophyllum papilluliferum Vuong, Aver. & Q.T.Truong , sp. nov.

( Figs. 4 & 5 ) Type: — VIETNAM. Ha Giang Province: Kim Linh District, limestone forest in Vi Xuyen Commune, 12 May 2020, Truong Ba Vuong,

BV726 (holotype VNM VNM00070769). Photos of plants used for the preparation of type specimen LE LE01255200 https://

en.herbariumle.ru/?t=occ&id=238726.

Diagnosis: — Bulbophyllum papilluliferum resembles to B. pyridion Vermeulen (1991: 217) in having a papillose ovary but differs from it in the finely papillulate surface of the peduncle and pedicel. Additionally, B. pyridion has a peduncle 10–13 mm long and sepals approximately 9.2 mm in length, which are roughly twice as long as those of B. papilluliferum , which has a peduncle 6–7 mm long and sepals 3–4 mm long.

Description: —Miniature epiphyte with plagiotropic creeping rhizome. Pseudobulbs close together, 1-leaved, oblong, very oblique, 2–5 mm long, surface verrucose, pseudobulbs covered with thin, white, remnant sheaths. Leaves with very short petiole ca. 1 mm long, leaf blade elliptic to narrowly elliptic, 5–9 mm long, 2–3 mm wide, acute, sometime shortly mucronate. Inflorescence arising from base of pseudobulbs, 1-flowered; peduncle terete, finely papillulate, 6–7 mm long, at base with 1–2 tubular bracts; floral bract tubular, ca. 1.5 mm long, apex acuminate; pedicel and ovary, 5–5.5 mm long, papillulate. Flower widely opening; sepals and petals orange with dark orange veins, lip orange red. Median sepal elliptic-oblong, 3–4 mm long, 1–1.3 mm wide, apex obtuse, mucronate. Lateral sepals ovate-triangular, 3.5–4 mm long, 1.5–2 mm wide, apex acute, with 3 main veins, lateral veins often forked. Petals oblong obovate, 1.5–1.8 mm wide, ca. 1 mm long, obtuse to sub-acute, 1–veined. Lip entire, simple, ovoid in outline, glabrous, 3–3.2 mm long, ca. 1 mm wide, attached to the column foot by a small yellow appendage, apex rounded; margins adaxially at basal half erect, forming a shallow groove; the margin in apical half of lip fold down, central part of the apex convex, forming lens-shaped callosity; abaxial side smooth without groove. Column erect, ca. 1 mm long; column foot ca. 1.5 mm long, distally upcurved; stelidia subulate pointing forward, slightly downcurved, ca. 1 mm long, lower margin with small triangular wing on each side; stigma rectangular; anther cap helmet-shaped, with red warty longitudinal band, small-beaked; pollinia 2, broadly obovate. Fruit not seen.

Etymology: —The species name refers to the papillulate peduncle, pedicel and ovary, unique character among its allies in Vietnam.

Habitat and phenology: —Creeping branch epiphyte. Humid broad-leaved evergreen forests. Flowers in March.

Distribution: —Species found only in type locality in northern Vietnam (Ha Giang Province).

Conservation assessment: — Bulbophyllum papilluliferum was collected from a single branch in the forest around Vi Xuyen Commune, Ha Giang Province, and its miniature size makes it prone to be overlooked.As detailed information about its habitat conditions, population size, and distribution is currently unavailable, conservation assessment is not possible. Accordingly, the species is assessed as Data Deficient (DD) globally.

Note: — B. papilluliferum differs from all known species of its section in papillulate peduncle, pedicel and ovary, and lip convex at apex. Morphological comparison of this plant with other Vietnamese species of B. sect. Macrocaulia is presented in Table 1.

7. Bulbophyllum physocoryphum Seidenfaden (1979: 51) , Averyanov et al. (2016b: 15), Averyanov et al. (2018: 6), Truong et al. (2019: 39).

( Fig. 1F )

Type: — THAILAND. Ranong: Muang Lan, 1966, Seidenfaden & Smitiand, GT 6211 ( C).

Habitat and phenology: —Creeping branch and canopy epiphyte. Evergreen, broad-leaved submontane forest on granite at elevation of about 950 m a.s.l. Flowers in February and May.

Distribution: — Vietnam (provinces Lam Dong and Gia Lai). Thailand, Cambodia.

Conservation assessment: — Bulbophyllum physocoryphum is known from only two sites in Vietnam. One of the site falls within the protected Kon Chu Rang area and the other in an unprotected site, where illegal collection for trade poses a significant threat. The species is experiencing a decline in population due to habitat degradation and human disturbance too, particularly at the unprotected location. And, in the coming time, it is most likely that threat will reach within protected area. Accordingly, two sites are treated as two locations. Based on available information, this species is assessed in Vietnam as Endangered (EN B2ab(iii,v)]. However, this species is distributed on both sides of Vietnam in Cambodia and Thailand ( POWO 2024), making chances of immigration of propagules from sites outside Vietnam possible. Accordingly, the preliminary assessment of EN is downlisted to Vulnerable [VU B2ab(iii,v)].

Note: —This species differs from all Vietnamese species of Bulbophyllum sect. Macrocaulia by having yellow green flowers. It was firstly recorded for Vietnamese flora by Averyanov in 2018.

Species examined: — VIETNAM, Gia Lai Province: K’Bang District, Son Lang Municipality, Kon Chu Rang Nature Reserve, forest, river bank, epiphytic, elevation 950 m a.s.l., May 2016, Nuraliev M.S., 1576 (photo LE LE01042147 https://en.herbariumle.ru/?t=occ&id=7655). VIETNAM, Lam Dong Province, Bao Loc District, February 2021, Truong Ba Vuong, Nghiem Xuan Son, BV1041 (VNM VNM00070762).

Figures

FIGURE 1. Flowers of species of Bulbophyllum section Macrocaulia in the flora of Vietnam. A. Bulbophyllum ovalifolium (specimen BV378 VNM00070770). B. B. malleolabrum (AL3183 LE01255063). C. B. catenarium (BV1210 VNM00070774). D. B. moniliforme (BV s.n. LE 01087378. E. B. ignevenosum (BV1794 VNM 00063960). F. B. physocoryphum (BV1041 VNM00070762). Photos by Truong Ba Vuong and L. Averyanov.

FIGURE 4. Bulbophyllum papilluliferum. A. Flowering plants. B. portion of peduncle. C. Flower, front view. D. Flowers. E. Median sepal, adaxial and abaxial side. F. Lateral sepals, adaxial and abaxial side. G. Petals, adaxial and abaxial side. H. Lip, views from different sides. I. Apical part of peduncle, pedicel, ovary and column, side view. J. Column, lip, and petal, side view. K. Column and lip, side view. L. Column, side view. M. Anther cap, view from different sides. N. Pollinia, front and rear view. Photos by Truong Ba Vuong from plants used for the preparation of the type specimen, BV726, photo-correction and design by L. Averyanov and T. Maisak.

FIGURE 5. Bulbophyllum papilluliferum. Flowering plants in natural habitat. Photos by Truong Ba Vuong of the plants used for the preparation of the type specimen, BV726.