taxonID	type	description	language	source
804578504352FFF048AE8389FA2FF7AE.taxon	discussion	The key is partly based on Rojchana-umpawan et al. (2014) and Suddee (2014). Didymoplexiella trichechus (J. J. Smith 1920: 19) Garay (1954: 34) is included provisionally, given its occurrence in the neighboring Thailand, and the high probability of confusion of this species with some of the species inhabiting Eastern Indochina. Morphological characters of D. trichechus are taken from Smith (1920), Rojchana-umpawan et al. (2014), Suddee (2014), Tsukaya et al. (2014) and Kumar et al. (2020). This species was described from Sumatra and is also known from Borneo and Peninsular Thailand.	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
804578504350FFF748AE8684FAE7FDF4.taxon	materials_examined	TYPE: — LAOS. Vientiane Province: Vang Vieng District, Phone Ngueng Area, 280 m elevation, 26 April 2012, Gale, Kumar, Santainsy, Phunthavong, HNL-KFBG 0007 (holotype HNL, isotype KFBG).	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
804578504350FFF748AE8684FAE7FDF4.taxon	biology_ecology	Ecology and phenology: — The species occurs between rocky crevices under broad-leaved lowland forest on limestone karst, under dry semi-deciduous forests on slopes of sandstone ridges, in humid evergreen submontane forests, usually among leaf litter in shady places, at elevations of 200 – 850 m. Flowers from April to September (October).	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
804578504350FFF748AE8684FAE7FDF4.taxon	distribution	Distribution: — Laos: Vientiane Province (Vang Vieng District), Khammoune Province (Nakai-Nam Theun National Park, Hin Nam No National Park). Vietnam: Quang Nam Province (Cu Lao Cham Island), Gia Lai Province (Kon Ka Kinh National Park).	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
804578504350FFF748AE8684FAE7FDF4.taxon	conservation	Conservation status: — In the protologue of D. laosensis, its conservation status was reasonably assessed as Endangered (EN B 1 + B 2 ab (iii )) based on the study of three scattered populations found in Vang Vieng District (Kumar et al. 2020). Additional locations of this species reported here considerably expand its known occurrence area and lead to the following amendment according to the criteria proposed by the IUCN Red List (2023): less than 10 distribution sites are recorded, the AOO does not exceed 500 km 2, and therefore the global conservation status is estimated as Endangered (EN B 2 ab (iii); B 2 for AOO <500 km 2, a for severely fragmented populations, b for continuously declined quality of habitat).	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
804578504350FFF748AE8684FAE7FDF4.taxon	discussion	Notes: 1. Didymoplexiella laosensis shows considerable morphological similarity with D. trichechus, and appears to differ from the latter species by oblong rectangular (vs obliquely quadrate to angular-round) side lobes of the labellum that project (vs do not project) beyond the median lobe (along the median axis of flower). Some of the specimens assigned here to D. laosensis (e. g. Averyanov et al. AL 891: Fig. 3 G, Tran Minh Duc et al. LTA 984) have side lobes of the labellum somewhat shorter than those described and illustrated in the protologue, hardly projecting beyond the median lobe. Such specimens approach D. trichechus in their morphology and make the delimitation between the two species imperfect. Additionally, an uncertainty exists regarding the range of variation of the labellum shape in D. ornata, which complicates consideration of the distinctness of D. laosensis from this species (see below). 2. Kumar et al. (2020) stated that in D. laosensis the longitudinal callus of the labellum terminates in more than 0.5 mm from the apex of the median lobe, and used this feature for differentiation of the species from D. ornata, D. siamensis and D. trichechus. However, this statement contradicts their drawing Fig. 2 E, and furthermore, additional specimens of D. laosensis studied here demonstrate this character to be equal to that of the other Indochinese species of Didymoplexiella. 3. Didymoplexiella laosensis is reported here for the flora of Vietnam for the first time. Three of the specimens cited here under D. laosensis were earlier assigned to other species of the genus: Averyanov et al. AL 891 from Laos was listed as D. ornata (Averyanov et al. 2019 b), Averyanov et al. AL 1086 from Laos was listed as D. ornata (Averyanov et al. 2019 b) or D. trichechus (Averyanov et al. 2019 a), and Nuraliev 1781 from Vietnam was listed as D. ornata (Nuraliev et al. 2019). After the description of D. laosensis, it became clear that these three specimens fit best the concept of this species in their long rectangular side lobes of the labellum usually projecting beyond the median lobe. 4. For D. trichechus, the indication by Averyanov et al. (2019 a) based on the specimen Averyanov et al. AL 1086 was the only published record from the countries of Eastern Indochina, and therefore we here reconsider the species as unknown from their territories.	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
804578504350FFF748AE8684FAE7FDF4.taxon	materials_examined	Additional specimens examined: — LAOS. Khammoune Province: Boualapha District, Langkhang Village, Nakai-Nam Theun Protected Area, steep southern slopes of sandstone ridge allied to the road from the north, around point 17 ° 34 ’ 02.2 ’’ N 105 ° 42 ’ 42.6 ’’ E, 200 – 535 m a. s. l., primary lowland semi-deciduous and evergreen dry forest on very steep rocky slopes, terrestrial achlorophyllous aphyllous herb to 20 cm tall on steep rocky slope, rare, 15 May 2018, L. V. Averyanov, Khang Sinh Nguyen, T. V, Maisak AL 1086 (LE: LE 01048691 https: // en. herbariumle. ru /? t = occ & id = 478); Boualapha district, Ban Dou Village, Hin Nam No Nature Protected Area, around Khuay Cave, 17 ° 30 ’ 35.1 ’’ N 105 ° 51 ’ 28.7 ’’ E, primary dry evergreen and semi-deciduous broad-leaved forest on very steep rocky slope near karstic hill top composed with solid, marble-like highly eroded limestone at 250 – 390 m a. s. l., achlorophyllous terrestrial herb on shady rocky slope, locally common, 10 May 2018, L. V. Averyanov, Khang Sinh Nguyen, T. V. Maisak, Littideth Xaiyavongsa, Siphanom Keovankham AL 891 (LE: LE 01048669 https: // en. herbariumle. ru /? t = occ & id = 53, LE 01048781 https: // en. herbariumle. ru /? t = occ & id = 3050). VIETNAM. Quang Nam Province: Hoi An City, Tan Hiep Municipality, Cu Lao Cham Island, 29 September 2020, Tran Minh Duc, Dinh Dien, Le Tuan Anh LTA 984 (photos LE: LE 01088173 https: // en. herbariumle. ru /? t = occ & id = 43691); Hoi An City, Tan Hiep Municipality, Cu Lao Cham Island, primarily dry semi-evergreen broad-leaved forests on sandstone mountains, around point 15.95000 ° N 108.52542 ° E, terrestrial holomycotrophic herb up to 20 cm, flower pinkish white, elevation of 200 – 450 m a. s. l., occasional, 23 June 2022, Nguyen Sinh Khang, Nguyen Huu Cuong, Dang Van Ha, Cao Xuan Hai 001 (photos LE: LE 01123549 https: // en. herbariumle. ru /? t = occ & id = 141856); same location, 24 June 2022, Nguyen Huu Cuong, Dang Van Ha, Nguyen Sinh Khang, Cao Xuan Hai CHKH 202206243073 (photos LE: LE 01123550 https: // en. herbariumle. ru /? t = occ & id = 141857); Gia Lai Province: K’Bang District, K’rong Municipality, Kon Ka Kinh National Park, 25 km NW of K’Bang Town, forest, 14 ° 18 ’ 25 ’’ N 108 ° 26 ’ 21 ’’ E, elevation 820 m, 14 May 2017, M. S. Nuraliev 1781 (LE: LE 01067821 https: // en. herbariumle. ru /? t = occ & id = 17410, photos LE 01089023 https: // en. herbariumle. ru /? t = occ & id = 65552).	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
804578504355FFF648AE8468FA91FD3D.taxon	materials_examined	TYPE: — MALAYSIA. Malacca, Bukit Sadanen, Derry s. n. (fide Seidenfaden 1975, 1978).	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
804578504355FFF648AE8468FA91FD3D.taxon	materials_examined	TYPE: — SINGAPORE. Stagmount, damp sandy woods on a stream bank, April 1907, Ridley s. n. (fide Seidenfaden 1975, 1978).	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
804578504355FFF648AE8468FA91FD3D.taxon	biology_ecology	Ecology and phenology: — The species inhabits primary and secondary tropical evergreen broad-leaved forests at elevations from sea level to 400 m. Flowers from April to July.	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
804578504355FFF648AE8468FA91FD3D.taxon	distribution	Distribution in the region of study: — Vietnam: Quang Ninh Province (Ha Long Bay). Distribution worldwide: — S Thailand: Phang Nga Province (Takua Pa), Nakhon Si Thammarat Province (Khao Nan), Trang Province (Khao Soi Dao), Yala province (Betong), Narathiwat province (Hala-Bala). Malaysia: Peninsular Malaysia (Negeri Sembilan: Bukit Tangga; Johor: Sedenak; Bukit Sadanen), Borneo. Singapore. Indonesia: Sumatra (South Sumatra Province: Bukit Besar).	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
804578504355FFF648AE8468FA91FD3D.taxon	conservation	Conservation status in the region of study: — The species is known in Vietnam from a single location, where a few mature individuals were observed (and unknown in Cambodia and Laos). Following the formal criteria of the IUCN Red List (2023), we tentatively assess the conservation status in the study area as Critically Endangered (CR) meeting the following conditions: A 1 a, c + 2 a, c, B 1 a, b (i, ii, iii, v) + 2 a, b (i, ii, iii, v), C 1 a (i, ii) + 2 a (i, ii), D. Outside the study area, the conservation status of D. ornata has not yet been assessed by the IUCN criteria and remains as Not Evaluated (NE).	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
804578504355FFF648AE8468FA91FD3D.taxon	discussion	Notes: 1. The limits of morphological variation of D. ornata, as well as the morphological and geographical delimitation of this species from some of its congeners, are not fully resolved. For example, Seidenfaden (1975, 1978) pointed that the Thai specimens assigned by him to D. ornata are quite similar to D. trichechus. Seidenfaden stressed that his identifications are questionable, and were partly induced by the geographical proximity of the Thai specimens to the type locality of D. ornata. Then, the drawing of a labellum of D. ornata provided by Kumar et al. (2020: Fig. 3 F) and stated to be “ drawn from colour photographs of plants in Malaysia provided by Ong Poh Teck and from original description (Ridley 1891) ” in fact differs significantly from the drawing included in the species protologue (Ridley 1891: Pl. 43 - 4). The protologue depicts a labellum with side lobes much longer and wider than the median lobe; the side lobes are forward directed at a sharp angle with the median lobe and therefore far project beyond it. The side lobes projecting beyond the median lobe make the drawing from Ridley’s work quite similar to the labellum shape of D. laosensis. Therefore, distinctness of D. laosensis from D. ornata is not completely clear. Unfortunately, Ridley (1891) has neither described nor depicted labellum ornamentation of D. ornata. Recollection of D. ornata from type locality is required for clarification of these uncertainties. 2. The Vietnamese specimen cited here is the only known record of D. ornata outside Malesia and Peninsular Thailand. Given its rather isolated geographical position and the uncertainties in species delimitation outlined here, we consider our identification of the specimen Hiep NTH 6271 as tentative. The labellum shape in this specimen is somewhat intermediate between the shapes depicted in the protologue of D. ornata and by Kumar et al. (2020): the side lobes are nearly of the same length and width as the median lobe, forward directed at a sharp angle with the median lobe but not projecting beyond it. 3. The specimens Averyanov et al. AL 891, Averyanov et al. AL 1086 (Averyanov et al. 2019 b) and Nuraliev 1781 (Nuraliev et al. 2019), which were earlier assigned to D. ornata, are identified here as D. laosensis (see note under the latter species). The third specimen cited by Averyanov et al. (2019 b), Averyanov et al. AL 995, bears only immature flower buds, and its identification remains uncertain. Thus, no occurrences of D. ornata are known from Laos after re-consideration of these collections.	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
804578504355FFF648AE8468FA91FD3D.taxon	materials_examined	Additional specimens examined: — VIETNAM. Quang Ninh Province: Ha Long Bay, Cong Do Island, around point 20 ° 52 ’ 371 ’’ N 107 ° 11 ’ 748 ’’ E, 9 May 2011, N. T. Hiep NTH 6271 (CPC Herbarium, LE: LE 01067822 https: // en. herbariumle. ru /? t = occ & id = 17411, photos LE 01089024 https: // en. herbariumle. ru /? t = occ & id = 65553).	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
80457850435BFFFD48AE8684FA91FEB0.taxon	materials_examined	LECTOTYPE (designated by Seidenfaden 1978: 176): — THAILAND. Chiang Mai Province: Doi Suthep, on humus in evergreen jungle, 2300 ft [700 m], 8 May 1910, A. F. G. Kerr 245 (K: K 000942689 https: // www. gbif. org / occurrence / 912692189 photo!).	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
80457850435BFFFD48AE8684FA91FEB0.taxon	materials_examined	TYPE: — VIETNAM. Quang Binh Province: Le Thuy District, Kim Thuy Municipality, around Lang Ho village at 16 ° 59 ’ 31 ’’ N 106 ° 38 ’ 31 ’’ E, old secondary broad-leaved closed forest on steep shale slopes of Khe Nuoc Trong River at elevation 150 – 200 m a. s. l., terrestrial achlorophyllous herb on steep shady slope, flowers light violet-brown, lip light violet with white apex, column white, not common, 9 April 2008, L. Averyanov, P. K. Loc, N. T. Vinh, N. S. Khang HAL 11443 (holotype HN!, isotypes LE: LE 01067829! https: // en. herbariumle. ru /? t = occ & id = 17417, MO: 100182465!, photos LE 01089015 https: // en. herbariumle. ru /? t = occ & id = 65544, LE 01089016 https: // en. herbariumle. ru /? t = occ & id = 65545).	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
80457850435BFFFD48AE8684FA91FEB0.taxon	materials_examined	TYPE: — JAPAN. Ryukyu Islands: Kagoshima Prefecture, Amami-Oshima Island, Amami City, Naze, 5 May 2018, Morita N 15 - 04 (holotype TNS, a flower in the spirit collection).	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
80457850435BFFFD48AE8684FA91FEB0.taxon	biology_ecology	Ecology and phenology: — The species grows in tropical to warm temperate regions, among leaf litter in shady primary to secondary humid to dry evergreen (or semi-evergreen and rarely deciduous) broad-leaved and mixed forests on limestone, shale and sandstone, at elevations of 100 – 1000 m. Flowers from March to July.	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
80457850435BFFFD48AE8684FA91FEB0.taxon	distribution	Distribution in the region of study: — Laos: Sekong Province (La Mam district). Cambodia: Koh Kong Province (Ta Tey Leu). Vietnam: Tuyen Quang Province (Na Hang District), Nghe An Province (Pu Mat National Park), Quang Binh Province (Phong Nha-Ke Bang National Park and districts Quang Ninh and Le Thuy), Quang Tri Province (Huong Hoa District and Da Krong District), Lam Dong Province (Bao Lam District). Distribution worldwide: — S Japan: Kagoshima Prefecture (Tanegashima, Yakushima and Amami Oshima islands). S China: Guangxi (Shiwandashan National Nature Reserve), Hong Kong. Taiwan: Taipei County (Chachiao), Pingtung County (Hengchun Peninsula). Thailand: Chiang Mai Province (Doi Suthep), Lampang Province (Doi Luang National Park), Phitsanulok province (Thung Salaeng Luang), Phetchabun Province (Nam Nao). Hainan is excluded from the known distribution of the species following the clarification by Hu et al. (2014).	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
80457850435BFFFD48AE8684FA91FEB0.taxon	conservation	Conservation status: — Locations of the species are confirmed in S Japan, S China, Taiwan, Thailand, SE Laos, SW Cambodia and Vietnam, forming a polygon with an extent of occurrence (EOO) greater than 1,000,000 km 2. The species therefore does not fit any criteria of threatened conservation categories proposed by the IUCN Red List (2023). Meanwhile, D. siamensis, as well as all its congeners, is strongly habitat-conservation-dependent and surely cannot survive on degraded soils in secondary plant communities. Taking into consideration the pronounced ongoing deforestation in the area inhabited by D. siamensis, we tentatively assess its conservation status as Near Threatened (NT).	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
80457850435BFFFD48AE8684FA91FEB0.taxon	discussion	Notes: 1. Hu et al. (2014) analysed the type material of D. siamensis and stated that they have designated a lectotype for this species. However, the lectotypification was performed prior to their study by Seidenfaden (1978), as shown below. Seidenfaden’s choice (which is identical with the one made by Hu et al.) has a priority according to Art. 9.19 of ICN (Turland et al. 2018). Downie (1925) cited two gatherings in the protologue of Leucolena siamensis, Kerr 245 and Kerr 305, both made in Doi Suthep. These gatherings should be treated as syntypes following Art. 9.6 of ICN (Turland et al. 2018). Downie did not indicate the place of their deposition. Seidenfaden (1978) indicated the specimen Kerr 245 at K as “ type ”, which at that time met the conditions for effective lectotypification (Art. 7.11 of ICN, Turland et al. 2018). Kumar & Gale (2020) cited the barcode K 000942688 for the lectotype of D. siamensis (Kerr 245), which is a mistake, because this barcode belongs to another gathering, Kerr 305 (a remaining syntype of this species), mounted on the same sheet with K 000942689. 2. Didymoplexis siamensis var. amamiana was described by Suetsugu & Hsu (2019) within their broad concept of the genus Didymoplexis, which implied merging of Didymoplexiella with Didymoplexis. This variety is treated as a synonym of Didymoplexiella siamensis in the POWO online database (Govaerts et al. 2023). We find this decision reasonable, because the variety was described as differing from Didymoplexiella siamensis s. s. solely by the very short stelidia. Indeed, the stelidia of Didymoplexis siamensis var. amamiana are much shorter than the anther, as seen in Fig. 1 from Suetsugu & Hsu (2019), whereas in Didymoplexiella siamensis s. s. (and in all the other species of Didymoplexiella) the stelidia are linear and at least twice longer than the anther (see references above). Suetsugu & Hsu (2019) described the variety on the basis of a single population, located in several hundred meters from a population characterised by long stelidia.	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
80457850435BFFFD48AE8684FA91FEB0.taxon	materials_examined	Additional specimens examined: — THAILAND. Chiang Mai Province: Doi Suthep, deer valley, on humus in evergreen jungle, 3000 ft [915 m], 19 May 1912, A. F. G. Kerr 305 (remaining syntype, K: K 000942688 https: // www. gbif. org / occurrence / 912692245). LAOS. Sekong Province: photo provided by Gale et al. (2018). CAMBODIA. Koh Kong Province: east of Ta Tey Leu, damp forest on a slope above a stream, 490 m elevation, 22 April 2018, Schuiteman et al. 18 - 44 (K, photos seen). VIETNAM. Tuyen Quang Province: Na Hang District, Xuan Tam Municipality, near Ban Cai village (22 ° 29 ’ 18 ’’ N 105 ° 19 ’ 47 ’’ E), primary broad-leaved evergreen dry forest on very steep slopes of highly eroded remnant limestone ridge at elev. 450 – 500 m a. s. l., dry steep slope with bamboo, terrestrial tuberiferous saprophyte, flowers with strong, very pleasant fragrance, tepals light purple-violet, column white, rare, 22 March 2001, P. K. Loc, N. X. Tam, L. Averyanov HAL 218 (paratypes of D. denticulata; HN, LE: LE 01067841 https: // en. herbariumle. ru /? t = occ & id = 17428, photos LE 01089014 https: // en. herbariumle. ru /? t = occ & id = 65543); Nghe An Province: Tuong Duong District, Tam Quang Municipality, Tung Huong village, [Pu Mat National Park,] along Khe Mat stream around point 19 ° 03 ’ 07 ’’ N 104 ° 36 ’ 57 ’’ E at elevation about 400 – 500 m a. s. l., lowland closed secondary old evergreen forest on steep slopes along rocky stream valley composed with stratified solid shale and sandstone, along ridge, terrestrial achlorophyllous herb, flowers bluish, very fragrant, very rare, 17 March 2007, L. Averyanov, P. K. Loc, N. V. Trai, N. T. Vinh, N. D. Phuong, A. Averyanova HLF 6672 (paratypes of D. denticulata; HN, LE: LE 01067845 https: // en. herbariumle. ru /? t = occ & id = 17433, MO: 100178408); Quang Binh Province: Bo Trach District, Tan Trach Commune, Phong Nha-Ke Bang National Park, forest, 17 ° 27 ’ 30 ’’ N 106 ° 12 ’ 56 ’’ E, elevation 550 m, 26 March 2022, M. S. Nuraliev, D. F. Lyskov, L. X. Dac, L. M. Ha, D. Q. Thang NUR 3540 (LE: LE 01168129 https: // en. herbariumle. ru /? t = occ & id = 134412, photos LE 01123111 https: // en. herbariumle. ru /? t = occ & id = 134290); Bo Trach District, Tan Trach Commune, Phong Nha-Ke Bang National Park, forest, not far from dry river bed, 17 ° 26 ’ 44 ’’ N 106 ° 13 ’ 05 ’’ E, elevation 320 m, 27 March 2022, M. S. Nuraliev, D. F. Lyskov, L. X. Dac, L. M. Ha, D. Q. Thang NUR 3557 (LE: LE 01168130 https: // en. herbariumle. ru /? t = occ & id = 134413, photos LE 01123115 https: // en. herbariumle. ru /? t = occ & id = 134294); Quang Ninh District, Truong Son Municipality, around Chan Trong village at 17 ° 10 ’ 49 ’’ N 106 ° 29 ’ 22 ’’ E, secondary dry broad-leaved forest on tops and steep slopes of highly eroded karst limestone mountain composed with gray solid marble limestone allied to Long Dai River, at elevation 300 – 400 m a. s. l., terrestrial achlorophyllous dull graybrownish saprophyte, flowers light violet, not rare, 13 April 2008, L. Averyanov, P. K. Loc, N. T. Vinh, N. S. Khang HAL 11521 (paratypes of D. denticulata; HN, LE: LE 01067833 https: // en. herbariumle. ru /? t = occ & id = 17421, LE 01067853 https: // en. herbariumle. ru /? t = occ & id = 17441, MO: 100182792, photos LE 01089017 https: // en. herbariumle. ru /? t = occ & id = 65546); Quang Tri Province: Huong Hoa District, Huong Phung Municipality, Sa Mui pass, around point 16 ° 47 ’ 42 ’’ N 106 ° 35 ’ 50 ’’ E at elevation about 1000 m a. s. l., secondary broad-leaved evergreen submontane forest on shale mountains, rocky shady stream slope with bamboo, terrestrial achlorophyllous olive-brownish to nearly black saprophyte, flowers white, lip light blue-violet, not common, 28 March 2006, L. Averyanov, P. K. Loc, P. V. The HLF 6263 (paratypes of D. denticulata; HN, LE: LE 01074683 https: // en. herbariumle. ru /? t = occ & id = 17594, photos LE 01089021 https: // en. herbariumle. ru /? t = occ & id = 65550, LE 01089022 https: // en. herbariumle. ru /? t = occ & id = 65551); Da Krong District, Huc Nghi Municipality, in vicinities of La To village around point 16 ° 29 ’ 16 ’’ N 107 ° 00 ’ 32 ’’ E at elevation about 414 m a. s. l., secondary broad-leaved evergreen lowland forest on montane hills composed with shale, very steep shady wet slope, achlorophyllous terrestrial saprophyte, flower white, very rare, 26 March 2006, L. Averyanov, P. K. Loc, P. V. The, N. S. Khang, N. V. Huy, D. C. Tri, L. M. Tuan, T. T. Tu, P. K. Vuong, P. V. Bao, P. X. Dieu, H. T. Phuong HLF 6216 (paratypes of D. denticulata; HN, LE: LE 01067837 https: // en. herbariumle. ru /? t = occ & id = 117679, photos LE 01089019 https: // en. herbariumle. ru /? t = occ & id = 65548, LE 01089020 https: // en. herbariumle. ru /? t = occ & id = 65549); Lam Dong Province: Bao Lam District, Loc Bao Municipality, 7 km NW of Loc Bao town, forest, near rocky river bank, 11 ° 50 ’ 19 ’’ N 107 ° 38 ’ 37 ’’ E, elevation 500 m, 21 April 2012, M. S. Nuraliev 586 (LE: LE 01067825 https: // en. herbariumle. ru /? t = occ & id = 17413, photos LE 01089025 https: // en. herbariumle. ru /? t = occ & id = 65554).	en	Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2023): The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam. Phytotaxa 620 (1): 18-32, DOI: 10.11646/phytotaxa.620.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.620.1.2
