Three new orchid species viz. Cyrtosia nana, Dendrobium parcum and Spathoglottis affinis are reported first time for the state of Assam from Dima Hasao district. The present paper enumerates all the three species with brief descriptions, habitat, distribution range, photos and illustrations. 

Keywords: Cyrtosia, Dendrobium, Spathoglottis, New record, Dima Hasao, Assam

The Dima Hasao district formerly known as North Cachar Hills is located in the southern part of Assam, India. The district lies within a geographical coordinate of 92°25'30" to 92°42'30"E latitudes and 24°56'30" to 25°51'10" N longitudes and covering a total land area of 4890 km². The eastern part of the district is bounded by Manipur and Nagaland, Meghalaya and Karbi-Anglong district by west, Nagoan and Karbi-Anglong District in north and the southern part of the district is bounded by Cachar (Anonymous, 2022). The district is mainly characterized by hilly ranges with different ecological settings of grassland to high-altitude vegetation. The highest peak of the district is 1932 meters, while the lowest one is 85 meters. The forest cover of the district is 88.71% of which only 187 km² (4.31%) is recorded under very dense forest while open forest occupies 61% of the total forest area. The various types of forests throughout the district have tropical evergreen forests, tropical semi-evergreen forests, tropical moist and dry deciduous forests, sub-tropical monsoon forests, secondary forests and bamboo forests endowed with rich biodiversity (Jarambusa and Baruah, 2023). Due to humid climate and availability of different forest types, the state of Assam including Dima Hasao district range has been reported to be rich in Orchid flora of economics and conservation significance (Gogoi, 2018). Present paper reported three new records of Orchid species collected from Dima Hasao range belonging to the genera Cyrtosia, Dendrobium and Spathoglottis.

Materials and methods 

During survey of orchids in different places in Dima Hasao district of Assam, we collected three different species of orchids. After consultation of available literatures (King and Pantling, 1898; Hegde, revised, 2017; Pradhan, 1979; Chowdhery, 1998; Pearce and Cribb, 2002; Lucksom, 2007; Chen et al., 2009; Rao, 2010; Gogoi, 2018, 2019; Misra, 2019; Singh et al., 2019) and critical examination of the flowers, all the specimen were identified. Critical review of the relevant literature (Hegde, revised, 2017; Chowdhery, 1998; Rao, 2010; Gogoi, 2018, 2019; Misra, 2019; Singh et al., 2019, Barbhuiya et al., 2021) revealed that among these species, Cyrtosia nana (Rolfe ex Downie) Garay, Dendrobium parcum Rchb.f. and Spathoglottis affinis de Vriese were not found reported in Orchid literatures of Assam, India. The present collection thus forms new records of these species from the state of Assam, India.

Result 3.1. 

Taxonomic treatment 

3.1.1. Cyrtosia nana (Rolfe ex Downie) Garay, Bot. Mus. Leafl. 30: 233. 1986. Yumkham et al. in Taiwania, 58 (3): 229. 2013. Galeola nana Rolfe ex Downie, Bull. Misc. Inform. Kew 1925: 409. 1925. [Figure 1 (A, B) and 2 (A-G)] Plants small, ± fleshy. Rhizome short, stout. Tuber-like roots pale yellowish white, cylindric, 2.5–9 cm, 5–8 mm in diameter, fleshy. Stem erect, yellowish white, slightly tinged with red, 10–22 cm tall, glabrous or apical half with sparse rust-coloured, mealy, short hairs, nodes with lanceolate scales; internodes usually 1–3 cm. Inflorescence terminal and lateral, sometimes lateral inflorescence very short or inconspicuous; terminal raceme 6–11-flowered; rachis rusty mealy-puberulent; floral bracts ovate-lanceolate, 2–4 mm, abaxially rusty puberulent; pedicel and ovary 8–10 mm, also with rust-coloured hairs. Flowers pale yellow, lip with orange-red longitudinal stripes. Sepals elliptic, 1–1.2 × ca. 0.6 cm, abaxially rusty mealy-puberulent, apex acute. Petals similar to sepals, slightly narrower, glabrous; lip ± embracing column, broadly ovate, ca. 1 × 1.2 cm, margin somewhat undulate, disk with a thick longitudinal ridge centrally, adaxially white pilose near apex. Column ca. 0.6 cm, apex slightly dilated.

Conclusion 

Hereby, C. nana, D. parcum and S. affinis are reported as new record for the flora of Assam. Along with these three new reports, a total recorded species of Cyrtosia will be 2, Dendrobium will be 65 and Spathoglottis will be 3 in Assam. Further exploration is needed to unveil the more hidden treasures of orchid flora from the biodiversity rich Dima Hasao range of Assam.

Acknowledgement 

We are thankful to the Department of Environment and Forest, Govt. of Assam and local forest officials of Dima Hasao range for help and logistic support during field work. We are thankful to villagers and local residents of Hamrung, Laisong, Jatinga, Haflong, Panimoor, Maibong, Umrangso for their support during the explorations. We are deeply thankful to Prandeep Gorlosa, Langbir Teron for logistic support.

Author’s contributions 

KG and JS equally contributed in data collection, preparation of the manuscript. KG was responsible for photo plate and line drawing, and JS was responsible for communication and research design.

Conflict of interest 

The authors declare that there is no conflict of interest.