Pelatantheria bicuspidata (Rolfe ex Downie) Tang & F.T.Wang (1951: 101)

Averyanov, Leonid V., Nguyen, Van Canh, Truong, Ba Vuong, Nguyen, Khang Sinh, Nguyen, Cuong Huu, Maisak, Tatiana V., Doan, Nga Thi, Nguyen, Tuan Hoang, Pham, Van The, Dat, Pham Thi Thanh, Thai, Tran Huy, Nguyen, Van Khuong & Trinh, Ngoc Bon, 2023, New orchids in the flora of Vietnam VI (Orchidaceae, tribes Arethuseae, Cymbidieae, Diurideae, Epidendreae, Vandeae, and Vanilleae), Phytotaxa 597 (2), pp. 87-110 : 104

Pelatantheria bicuspidata (Rolfe ex Downie) Tang & F.T.Wang (1951: 101) , Seidenfaden (1988: 116), Chen et al. (2009: 457), Zhou et al. (2016: 105). Type: — THAILAND. FLORA OF SIAM, Chiengmai, 1000 ft., Me Sue, 1400 ft., August 8 1912, A.F.G. Kerr 151 (lectotype K000942419, designated here, isolectotype K000942420). ( Fig. 9 )

≡ Sarcanthus bicuspidatus Rolfe ex Downie (1925: 391) , non Smith (1912: 84).

Ecology and phenology:—Creeping epiphyte and lithophyte. Primary and secondary evergreen broad-leaved forests on limestone and sandstone at an elevations of 500–700 m a.s.l. Locally common. Flowers in May–July.

Distribution:— VIETNAM, provinces Dien Bien (Muong Nhe District) and Son La (Mai Son District). Thailand, S China.

Conservation status:—Discovered populations of this species do not currently exhibit a clear tendency to decrease, according to available collections and field observations. However, the deforestation, the decreasing habitat quality, and the occurrence area are observed obvious factors that may affect the species in the near future. According to our estimation, the conservation status of this species may be nationally Near Threatened (NT). The conservation status of this species outside Vietnam was not evacuated (NE).

Notes:—The distribution of this species in Vietnam may be wider than reported here on the basis of verified herbarium specimens. Some herbarium specimens of this species may be mixed with doubtfully identified sterile specimens of the more common P. ctenoglossum Ridley (1896: 372) , or P. insectifera ( Reichenbach 1857: 159) Ridley (1896: 373) .

Among two type specimens housed at K Herbarium, the specimen K000942419 , which has a better-preserved flower, is chosen as a lectotype .

Studied specimen:— VIETNAM, Son La Province, Mai Son District, Hat Lot Town , around point 21°13´05´´N 104°06´44´´E, secondary evergreen dry open broad-leaved forest on very steep rocky slopes and tops of a remnant mountain composed with highly eroded marble-like solid crystalline limestone at an elevation of 550–650 m a.s.l., lithophytic herb on open rocky slope, common, 21 December 2010, L. Averyanov, P.K. Loc, P.V. The, N.T. Vinh, CPC 1148 ( LE01074983 https://en.herbariumle.ru/?t=occ&id=45126, photos LE01123130 https://en.herbariumle. ru/?t=occ&id=136902); fl. in cult 17.06.202 2, L. Averyanov, CPC 1148 ( LE01168945 https://en.herbariumle.ru/?t=occ&id=140381) . VIETNAM, Dien Bien Province, Muong Nhe District, Muong Nhe Natural Reserve, Chung Chai Municipality , near Doan Ket Bridge , around point about 22º17´16´´N 102º23´58´´E, elevation of 550–650 m a.s.l., secondary evergreen broad-leaved lowland forest on mountain slopes composed with sandstone at an elevations of 550–650 m a.s.l., epiphyte on tall tree, not common, 20 May 2022, L. Averyanov, Tran Huy Thai, Khang Sinh Nguyen, T. Maisak, VR 1779 ( LE01169003 https://en.herbariumle.ru/?t=occ&id=140480, photo LE01123344 https:// en.herbariumle.ru/?t=occ&id=137132) .

Figures

FIGURE 9. Pelatantheria bicuspidata (Rolfe ex Downie) Tang & F.T.Wang. A. Flattened flowering plant. B. Intact inflorescence. C. Flattened inflorescences. D, E. Intact flowers, frontal and side views. F. Separate flowers, frontal and half-side views. G. Separate flower, view from back. H. Flattened flowers with exposed back-wall of the spur (frontal part of the lip removed), frontal and half-side view. I. Spur back-wall, frontal and half-side view. J. Flattened, sagittal section of the lip and column. K, L. Lip and column with anther cap, frontal and side view. M, N. Lip and column with anther cap removed, frontal and side view. O. Lip, frontal view. P. Lip, with exposed front-wall of the spur, side view and view from inside. Q. Lip, view from below. R.Anther cap, view from different sides. S. Pollinarium, view from different sides. All photos were made by L. Averyanov from the specimen, L. Averyanov CPC 1148, with photo correction and design by L. Averyanov and T. Maisak.