Schoenorchis seidenfadenii Pradhan (1978: 912)

Averyanov, Leonid V., Nguyen, Van Canh, Vuong, Truong Ba, Quang, Bui Hong, Nguyen, Khang Sinh, Le, Tuan Anh, Binh, Tran Duc, Maisak, Tatiana V. & Nguyen, Cuong Huu, 2025, New orchids in the flora of Vietnam X (Orchidaceae, Orchidoideae, tribe Orchideae, Epidendroideae, tribes Gastrodieae, Arethuseae, Cymbidieae, and Vandeae), Phytotaxa 681 (1), pp. 20-54 : 49-50

Schoenorchis seidenfadenii Pradhan (1978: 912) , Seidenfaden (1988: 67, fig. 35, plate 6b), Ormerod et al. (2021:

222).

= Schoenorchis fragrans auct. non Seidenfaden & Smitinand (1963: 611, quoad name): Seidenfaden & Smitinand (1963: 611, fig. 459, quoad plant).

( Fig. 15 )

Type: — THAILAND. Chiang Mai Province: Doi Sutep Mt., G. Seidenfaden, T. Smitinand GT2602 ( C fide Pradhan 1978: 912).

Ecology and phenology: —Miniature branch epiphyte. Lowland and submontane dry evergreen forests. Flowers in July.

Distribution: — Vietnam (Gia Lai Province, Dak Doa District). Myanmar, Thailand.

Conservation status: —Currently, Schoenorchis seidenfadenii is known in Vietnam from a single location found in an area having no official protection and experienced with wide deforestation and land development. These are indicators of continuing decline in the quality of habitat. The AOO is estimated to be less than 10 km 2. With this information, the species can be assessed as Critically Endangered [CR B2ab(iii)]. The species is further distributed in Myanmar and Thailand. Hence, there is a chance of immigration of propagules from adjacent countries. Accordingly, the preliminary assessment of CR is downlisted to Endangered [EN B2ab(iii)] for Vietnam.

Notes: —The formal record of this species for Vietnam ( GBIF & POWO 2024) is based on a wrongly identified specimen (HAL1084) housed at MO, which in fact is an isotype of S. scolopendria Averyanov (2012: 134) . In this connection, the discovery presented here is the first verified record of S. seidendfadenii in Vietnam. It essentially expands the species area to the east. Schoenorchis seidenfadenii in plant habit is superficially very similar to S. fragrans and S. phitamii Averyanov in Averyanov et al. (2017: 25). However, in flower structure, it well differs in twin callus on the lip disc (vs. callus entire). Flowers of S. seidenfadenii are very similar to flowers of S. scolopendria Averyanov (2012: 134) , but the first species strikingly differs in a short, erect stem (vs. a long, creeping stem).

Studied specimen: — VIETNAM, Gia Lai Province, Dak Doa District, plant obtained from local collectors, 16 July 2024, Nguyen Van Canh, AL3274 (LE: LE01255163 https://en.herbariumle.ru/?t=occ&id=229785).

Figures

FIGURE 15. Schoenorchis seidenfadenii. A, B. Flowering wild collected plants. C–F. Flower, front, half-side, and side views.All photos by Nguyen Van Canh from specimens AL3274. Photo correction and design by L. Averyanov.