Trachoma rhopalorrhachis (Reichenbach) Garay (1972: 208)

Averyanov, Leonid V., Thai, Tran Huy, Truong, Ba Vuong, Nguyen, Van Canh, Nguyen, Tuan Hoang, Maisak, Tatiana V., Nguyen, Khang Sinh & Nguyen, Van Khuong, 2022, New orchids in the flora of Vietnam (Orchidaceae, Aeridinae), Phytotaxa 555 (2), pp. 113-135 : 128

Trachoma rhopalorrhachis (Reichenbach) Garay (1972: 208) .

≡ Dendrocolla rhopalarrhachis Reichenbach (1857: 40) .

( Figs. 8 C, D )

Type: — INDONESIA. W Java “Rchb.fil. Provinz Bandong. Zollinger Sine Nr. ” ( W? not seen) .

Habitat, phenology and conservation status: —Epiphyte. Broad-leaved evergreen lowland and submontane forests on granite at elevation 600–800 m a.s.l. Fl. October–November. Rare. Suggested IUCN Red List status – EN.

Distribution: —Southern Vietnam (Dak Lak and Lam Dong provinces), Thailand, Malaysia, Indonesia, Philippines, New Guinea, NE Australia.

Note: —This widespread species with fugacious, very short lived flowers attracts little attention from orchid collectors and is poorly represented both in living and herbarium collections. Its two documented locations in Dak Lac province (Chu Mu and Chu Yang Sinh Mountains) and two in Lam Dong province (both in Dalat Town area) indicate an area of occurrence (EOO) in Vietnam less than 5000 km 2. All observed populations are very small and surely form very small area of occupancy (AOO) due to severe fragmentation of suitable environment as a result of intensive deforestation and agricultural land development throughout the distribution area. The wide loss of habitats are strong factors that identify the conservation status of this species in Vietnam as nationally Endangered – EN B1ab(iii), B2ab(iii) according to formal IUCN criteria ( IUCN 2019).

Studied specimens: — VIETNAM, Lam Dong Province, Dalat Town area, 16.05.2000, L. Averyanov s.n. (LE01076678 https://en.herbariumle.ru/?t=occ&id=57557). VIETNAM, Lam Dong Province, wild collected plant cultivated in Dalat Town private collection, Dang s.n. photo, 2010 (LE01122321 https://en.herbariumle. ru/?t=occ&id=82807). VIETNAM, herbarium specimen and photos prepared on 19 October 2017 by L. Averyanov and T. Maisak, AL 335 from plant collected by Nguyen Van Canh , s.n., in Dak Lak Province, M Drac District, Chu Mu Mountain, at 600–800 m a.s.l. on 15 September 2016 (LE01076423 https://en.herbariumle.ru/?t=occ&id=57303, LE01076427 https://en.herbariumle.ru/?t=occ&id=57307, LE01122490 https://en.herbariumle.ru/?t=occ&id=82980). VIETNAM, herbarium specimen on 30 October 2018 by L. Averyanov, T. Maisak, AL 100 from plant collected by Nguyen Van Canh s.n. in Dak Lak Province, Chu Yang Sinh Mountains on 30 November 2015, flowers white, with light sweet fragrance; each tepal with brown round spot near the base; lip with yellow spot at the disc and brown spots on sides; column white with brown spot on lateral sides; anther white (LE01076428 https://en.herbariumle. ru/?t=occ&id=57308).

Figures

FIGURE 8. Pomatocalpa undulatum. A, B. Inflorescences and flower, frontal view (BV 517). Trachoma rhopalorrhachis. C, D. (AL 335). Trichoglottis maculata. E. Flowering plant (Nguyen Hoang Tuan s.n.). F. Flower, frontal view (BV 685). Photos by Truong Ba Vuong (A, B, F), L. Averyanov (C, D), Nguyen Hoang Tuan (E).