Rhomboda aurea (Aver.) Ormerod & Aver., 2023

Averyanov, Leonid V., Nguyen, Van Canh, Vuong, Truong Ba, Nguyen, Khang Sinh, Nuraliev, Maxim S., Nguyen, Cuong Huu, Ormerod, Paul A., Maisak, Tatiana V., Diep, Dinh Quang, Lyskov, Dmitry F. & Nong, Duy Van, 2023, New orchids in the flora of Vietnam VII (Orchidaceae: tribes Cypripedieae, Cranichideae, Orchideae, and Collabieae), Phytotaxa 619 (4), pp. 255-276 : 265

Rhomboda aurea (Aver.) Ormerod & Aver. , comb. nov.

≡ Odontochilus aureus Aver. in Averyanov et al. (2015: 176), non (J.J.Sm.) T. Yukawa (2016: 106). Type:— VIETNAM. Nghe An Province: Ky Son District, Na Ngoi Municipality, eastern slopes of Phu Xai Lai Leng Mountain, primary and secondary broad-leaved forest on steep mountain slopes composed of sandstone and gray shale at elevation 1300–2000 m, around point 19°12’54’’N 104°12’01’’E, creeping terrestrial herb on shady steep slope, leaves nearly almost black with median whitish stripe, not common, 26 October 2013, L.Averyanov, N.T.Hiep, N.S.Khang, L.M.Tuan, N.A.Trang, L.H.Dan CPC 6323 (holotype LE01074327 https://en.herbariumle. ru/?t=occ&id=44115, isotype CPC Herbarium).

Epitype: — VIETNAM. Nghe An Province: Ky Son District, Na Ngoi Municipality, eastern slopes of Phu Xai Lai Leng Mountain , fl. in cult. in September 2014, flowers odorless, sepals and petals light olive green flushed with brown-purple to apex, lip golden-yellow, spur red, column dull yellow, ovary and floral bract dark reddish-brown, L.Averyanov CPC 6323 a ( LE01074328 https://en.herbariumle.ru/?t=occ&id=44116, authentic photos LE01090263 https://en.herbariumle.ru/?t=occ&id=77893, LE01090264 https://en.herbariumle.ru/?t=occ&id=77894) .

Notes:—We transfer this species to the genus Rhomboda Lindley (1857: 181) on the basis of the following features: leaves with a median white stripe, flowers resupinate for 3/4, broad petals, relatively large hypochile, rather short mesochile, and large epichile (in Odontochilus , hypochile is small and semi-globose, and mesohile is longer than epichile), single large gland on each side of the hypochile, a median keel (septum) on the lip ending distally into two low keels, broad column wings with small lobe at the column back (that are particularly typical of Rhomboda ), and the stigma lobes arranged on the sides of the column under the anther cap. Rhomboda aurea , however, is unique within Rhomboda in its yellow and red lip and a very low bicarinate median keel on the lip disk. It belongs to the species group comprising also R. fanjingensis Ormerod (1995: 327) , R. longifolia Lindley (1857: 181) , R. monensis Odyuo et al. (2019: 61) , R. moulmeinensis (C.S.P.Parish & Rchb.f. in Reichenbach 1874: 142) Ormerod (1995: 325), R. petelotii ( Gagnepain 1933: 349) Ormerod (1998: 11) , R. pulchra ( King & Pantling 1896: 127) Ormerod & Bhattacharjee (2014: 177) , and R. wardii Ormerod (1995: 327) (which is characterized by a uniform plant appearance and dark green, brown, or almost black velvety leaves with a white longitudinal stripe). A detailed description, illustrations, and data on the ecology, phenology, and distribution of R. aurea were provided in its protologue ( Averyanov et al. 2015).