A Critically Endangered new species from Kachin State, Myanmar: Dendrobium naungmungense

Dendrobium naungmungense, a new species from Naungmung, Kachin State, North Myanmar, is described and illustrated.

The orchid flora of Myanmar is highly diverse but poorly known, as a result of the past political isolation and instability of the country. The remoteness of many orchidrich areas and the difficulties of investigation in rugged terrain have also played a role. According to recent estimates, about 800 orchid species are distributed in Myanmar. but this is probably an underestimate. Many new distribution records and new species have been published in the last few years. Dendrobium Swartz (1799: 82) (Orchidaceae: Epidendroideae; Dendrobieae) is one of the largest genera of Orchidaceae, with approximately 800–1500 species, which are mainly distributed in diverse habitats in South, East and South-east Asia and Australasia, including the Philippines, Borneo, Australia, New Guinea and New Zealand. 

During our fieldwork in Khakaborazi National Park, Kachin State, Northern Myanmar since 2015, one new species of Dendrobium has been discovered, and named after Naungmung.

Dendrobium naungmungense is only known from the type locality. It is epiphytic on the trunk of riparian trees in tropical rainforest, which is dominated by Dipterocarpus obtusifolius Teijsm. ex Miq. (Dipterocarpaceae). Dendrobium naungmungense was collected in Naungmung Town, Kachin State, Northern Myanmar. Until now, only one population, consisting of ca. 20 mature individuals, has been discovered in 3 years of continuous field investigations (2015–2017). In addition, population growth and human activities have led to serious habitat destruction and deforestation in this region. It is also illegally collected by local people due to the highly ornamental and medicinal values. A preliminary risk-of-extinction assessment shows that the new species should be regarded as Critically Endangered (CR) according to the IUCN Red List Categories and Criteria.

Morphologically, D. naungmungenseis is similar to D. vexabile and D. ciliatilabellum, which are characterised by branched stems, short inflorescences with 1 or 2 flowers, lip 3-lobed with a narrow claw and flowers yellowish green, except the lip with purple streaks or spots. However, the new species differs from D. vexabile and D. ciliatilabellum by having a wide mentum, small hypochile, oblong epichile with 3 ciliate laminae and margin crisped with dense hairs and column wing with significant denticulation.

This work was financially supported by a project of the Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences (Y4ZK111B01).The result published as " Dendrobium naungmungense (Orchidaceae, Dendrobieae), a new species from Kachin State, Myanmar" on PhytoKeys.

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 Dendrobium naungmungense. A Habitat B Plant C Flower D Lateral view of flower E Sepals and petals F Column G Front view of labellum H Lateral view of labellum J Abaxial and adaxial anther cap K Pollinarium I Column wing (Photographed by Q. Liu).

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A Dendrobium naungmungense (A–1 Front view of flower A–2 Lateral view of flower A–3 Labellum A–4 Front view of column A–5 Lateral view of column A–6 Column wing) B Dendrobium vexabile (B–1 Front view of flower B–2 Lateral view of flower B–3 Labellum B–4 Front view of column B–5 Lateral view of column B–6 Column wing) (Photographed by Q. Liu)