3. Bulbophyllum fenestratum Smith (1907: 48), Vermeulen et al. (2015: 76).

Type:— INDONESIA. Bangka Island, 1901, Hort. Bogor, s.n. (lectotype, BO)

(Fig. 3)

= B. dentiferum Ridley (1915: 166) . Type:— THAILAND. Koh Samui, Robinson 5719 (holotype, photo, K000891022!).

Distribution: — Vietnam (Dong Nai Province), Thailand, Malaysia, Sumatra, Java.

Habitat and phenology: —Lithophyte on granite, in evergreen broad-leaved lowland forest on steep rocky slopes at elevation of about 250 m a.s.l. Flowers in June–July.

Species examined: — VIETNAM. Dong Nai Province, Tan Phu District, Phu Trung Commune, 23May2023, Truong Ba Vuong BV 1737 (VNM 00063989, analytical photos LE01124298 https://en.herbariumle.ru/?t=occ&id=186068), BV 1738 (VNM 00064010) , BV 1739 (VNM 00064009), BV 1740 (VNM 00064008) .

Conservation assessment: —The data about the natural conditions of the species’ habitat and its population size remain unclear. However, the commercial harvesting of plants for sale infers a decline in the number of mature individuals. The total expanse of this species in Vietnam is not known but it is inferred that the Extent of Occurrence (EOO) and the Area of Occurrence (AOO) are less than 100 and 12 km 2, respectively. The species is known further from Borneo, Java, Malaya, Sumatera and Thailand (POWO 2023). Due to a lack of proper information, this species can be assessed as Data Deficient.

Note: —The flowers of Bulbophyllum fenestratum have a color scheme similar to that of B. andersonii (Hooker 1890: 777) Smith (1912: 22) and B. sondangii Vuong & Aver. in Minh Quan Dang et al. (2023: 204) with pinkish to dark pink lateral sepals. However, B. fenestratum has a prominent tooth on the inner side of the stelidia, which is a key character of all species of B. sect. Cirhopetalum s. str. The present report represents a new record of this species in the flora of Vietnam.