Dendrobium nobile var. luteoalbum Aver.

Averyanov, Leonid V., Nguyen, Van Canh, Vuong, Truong Ba, Nuraliev, Maxim S., Nguyen, Khang Sinh, Maisak, Tatiana V., Yudova, Daria A., Saidov, Nikita T., Nguyen, Cuong Huu & Nong, Duy Van, 2024, New orchids in the flora of Vietnam VIII (Orchidaceae: Epidendroideae, tribes Malaxideae, Neottieae and Podochileae), Phytotaxa 658 (1), pp. 1-49 : 22-24

Dendrobium nobile var. luteoalbum Aver. , nom. nov.

( Fig. 10E, F )

≡ Dendrobium nobile var. alboluteum Duong & Averyanov (1989: 1039) , nom. illeg., non Lindley (1898: 45, pl. 645–646).

Type: — VIETNAM. [Gia Lai Province] Gialai-Kontum Province: Chupa [Chu Pah], Gia Lu, 21 May 1985, Averyanov et al., LX-VN2107 (lectotype, designated here LE LE 01066489! https://en.herbariumle.ru/?t=occ&id=14858, drawing LE LE 01088760 https:// en.herbariumle.ru/?t=occ&id=65268, photos LE LE 01088761 https://en.herbariumle.ru/?t=occ&id=65269, isolectotype HN!).

Habitat and phenology: —Clustering epiphyte. Primary and old secondary lowland and submontane broad-leaved evergreen forests on limestone and granite at elevations of about 150 m a.s.l. Rare. Flowers in March–April.

Distribution: — Vietnam: provinces Dien Bien (sine loc.), Gia Lai (Chu Pah District) and Dak Lak (sine loc.). Laos: Khammouane Province.

Conservation status: —Several localities of Dendrobium nobile var. alboluteum are known.They are considerably distant from each other and outline a large area of extension of this taxon ranging over Laos, N and S Vietnam. However, available information on its natural populations is very scarce. Most of them are known to be severely depleted by commercial collecting due to high market demands. It is also apparent that the area and quality of habitats of this taxon, particularly at low elevations, decrease rapidly due to the degradation of lowland forests. Taking into account these conditions, we estimate the global conservation status of D. nobile var. luteoalbum as Near Threatened (NT).

Notes: —In the protologue of D. nobile var. alboluteum D.H.Duong & Aver. , a single gathering was cited, which was indicated to be deposited in two Herbaria ( HN and LE) without designation of a holotype. At that time, it has not precluded a valid publication of a new species or infraspecific taxon (Art. 40.7 of ICN; Turland et al. 2018), and the HN and LE specimens are to be treated as syntypes (Art. 9.6 of ICN). At LE, we found a single specimen of this gathering. We selected the LE specimen as the lectotype following Arts. 9.3 and 9.11 of ICN as it represents best the species.

Duong & Averyanov (1989) while describing D. nobile var. alboluteum D.H.Duong & Aver. overlooked the existence of the name D. nobile var. alboluteum Lindl. Dendrobium nobile var. alboluteum D.H.Duong & Aver. is a later homonym of D. nobile var. alboluteum Lindl. , and therefore the former name is illegal. This inconsistency has never been addressed until now. Here we formally correct this mistake by publication of a replacement name, D. nobile var. luteoalbum Aver. This variety comprises plants of D. nobile s.l. with sub-albino flowers, broad suborbicular lip with round apex, and commonly (1)2–3-flowered inflorescences ( Duong & Averyanov 1989). The flower of this variety is commonly white, with yellowish center of the lip. This rather rare taxon occurs at lower elevations than D. nobile var. nobile , which is very common in the highlands of Vietnam.

At the same time, D. nobile var. alboluteum Lindl. is, to our opinion, hardly distinguishable from the type variety of D. nobile .

Additional specimens studied:— LAOS. Khammouane Province: about 10 km to the E from Thaket City by road 12, around point 17°26’53.3”N 104°52’09.4”E at elevation about 150 m a.s.l., very dry broad-leaved secondary semideciduous open forest and scrub on rocky crystalline limestone, epiphyte, 6 March 2013, L. Averyanov, N.T. Hiep, V. Lamxay, N.S. Khang, P.V. The, S. Lorphengsy, LA-VN 227a (photos LE LE01088861 https://en.herbariumle.ru/?t=occ&id=65372). VIETNAM. Dien Bien Province: wild collected cultivated plant, December 2010, L. Averyanov s.n. (photos LE LE01088762 https://en.herbariumle.ru/?t=occ&id=65270). VIETNAM. Dak Lak Province: wild collected plant cultivated in garden of Nguyen Van Canh, 19 April 2008, N.V. Canh s.n. (photos LE LE01088859 https://en.herbariumle.ru/?t=occ&id=65370).

Dendrobium polyanthum Wall. ex Lindley (1830: 81) , Schuiteman et al. (2008: 286), Chen et al. (2009: 380), Rokaya et al. (2013: 526), Jalal & Jayanthi (2015: 20), Zhou et al. (2016: 49), Aung et al. (2020: 81), Ormerod et al. (2021: 114), Teoh (2021: 350), Jin et al. (2023: 360), Phonepaseuth et al. (2023: 32).

( Fig. 10G–I )

Type: — MYANMAR. Mon State: Mawlamyine District, Wallich, Numer. List: no. 2009 (holotype K, fide Ormerod et al. 2021).

= D. cretaceum Lindley (1847b : tab. 62), Gagnepain in Gagnepain & Guillaumin (1932: 212), Holttum (1964: 289), Seidenfaden (1972a: 118, 1975a: 42, 1976: 14, 1985: 75, 1992: 234), Bose & Bhattacharjee (1980: 206), Pearce & Cribb (2002: 425). Lectotype (designated by Seidenfaden (1985: 75)):— INDIA . Khasi Hills, W. Griffith s.n. (K K000894429 photo!).

Habitat and phenology in Vietnam: —Clustering epiphyte. Primary and secondary evergreen broad-leaved forests at elevations of 700–1800 m a.s.l. Very rare. Flowers in February–May (under cultivation).

Distribution: — Vietnam: provinces Son La (sine loc.) and Lam Dong (Lam Ha District). Nepal, NE India , Myanmar, SW China, Thailand, Laos.

Conservation status in Vietnam: — Dendrobium polyanthum is known to have a disjunctive distribution within the country, with two isolated localities in Son La and Lam Dong provinces that are more than 1100 kilometers apart. The known populations are highly fragmented, severely depleted by commercial collecting, and have a very small extent of occurrence (surely <100 km 2). Agricultural land transformation, deforestation and selective forest logging lead to irreversible decrease of habitat quality in both known localities. Considering these conditions, we estimate the national conservation status of the species as Critically Endangered (CR) with the following criteria: A2a,c,d, B1ab(i–iii)+B2ab(i–iii). Jin et al. (2023) assessed the status of this species as Vulnerable (VU) but have not provided any details or reasons for their decision.

Notes: —For the last 30 years, D. polyanthum was continuously reported for the flora of Vietnam by various authors ( Seidenfaden 1985, 1992, Averyanov 1988, 1994, Pearce & Cribb 2002, Averyanov & Averyanova 2003, Schuiteman et al. 2008, Chen et al. 2009, Zhou et al. 2016, Ormerod et al. 2021, Jin et al. 2023). However, the identification of these records was based on a drawing by Ho (1972: 1058, fig. 5142 reproduced in 1993: 1031, fig. 10029, and in 2000: 823, fig. 11043), where, to our opinion, under the name D. cretaceum another species, D. crumenatum Swartz (1799: 237) (belonging to D. sect. Rhopalanthe) is depicted (see also Seidenfaden 1985, 1992). Ho indicated the location as “Dinhquan, Bienhoa”, which corresponds to Dinh Quan Town in Dong Nai Province of southern Vietnam. According to our observations, D. crumenatum is fairly common in that area. We therefore agree with Seidenfaden (1992) that until now no specimens from Vietnam undoubtedly belonging to D. polyanthum were available. Thus, the records reported here represent the first documented evidence of D. polyanthum in the flora of Vietnam. Sepals and petals of the Vietnamese plants vary from pure white to pink or light purple; the lip is always white with light reddish-brown veins at the center, which is known to be typical for D. polyanthum .

Studied specimens:— VIETNAM. Wild collected plant originated from northwestern Vietnam, found in Hanoi street market, flowers odorless, entirely white, photos made on 22 April 2015, L. Averyanov, T. Maisak, AL2816 (photos LE LE01088809 https://en.herbariumle.ru/?t=occ&id=65317). VIETNAM. Wild collected plant originated from Son La Province and cultivated in private garden in Hanoi, photos made in 2004, L. Averyanov, AL2817 (photos LE LE01088817 https://en.herbariumle.ru/?t=occ&id=65325). VIETNAM. Lam Dong Province: Lam Ha District, Phi To Village, wild collected plant cultivated in garden of Ly Ngoc Quan, originated from mountains nearby, photos made on 19 February 2023, L. Averyanov, Nguyen Van Canh, AL2079 (photos LE LE01123829, https://en.herbariumle. ru/?t=occ&id=165198).

Figures

FIGURE 10. A. Dendrobium lampongense. Photo by L. Averyanov from the specimen L. Averyanov, T. Maisak, AL2814. B–D. Dendrobium densiflorum. Photos by L. Averyanov from the specimen L. Averyanov et al., VR1800. E, F. Dendrobium nobile var. luteoalbum. Photos by L. Averyanov from living plant prior to the preparation of the type herbarium specimen L. Averyanov et al., LX- VN2107. G–I. Dendrobium polyanthum. Photos by L. Averyanov from the specimen L. Averyanov, T. Maisak, AL2816. Photo correction and design by L. Averyanov.