319 Received: 27.06.2019; Revised & Accepted: 18.12.2019 Published Online: 31.12.2019 Abstract: Oberonia maxima C.S.P.Parish ex Hook.f., and Thrixspermum formosanum (Hayata) Schltr., so far known from northeast India, are reported here for the first time from Tamil Nadu, Peninsular India. Detailed descriptions and photographs are provided for easy identification. Keywords: New Record, Oberonia maxima , Orchidaceae, Tamil Nadu, Thrixspermum formosanum. Introduction During recent field explorations in the forests of Mukurthi National Park, Nilgiri Biosphere Reserve, Tamil Nadu, the authors have collected interesting specimens belonging to the genera Oberonia and Thrixspermum of Orchidaceae. The genus Oberonia Lindl. is represented by about 350 species (Prasad et al. , 2018; Govaerts et al. , 2019) while Thrixspermum Lour by c. 151 species (The Plant List, 2013). Sixty nine species of Oberonia have been reported from India, mainly found in Peninsular India, north-eastern states, Andaman and Nicobar Islands, central India and Western Himalaya (Ansari & Balakrishnan, 1990; Kumar & Manilal, 1994; Misra, 2007; Narayanan et al. , 2010; Chowlu et al. , 2015; Chowlu & Rab, 2017; Prasad et al. , 2018). Thrixspermum is represented by about 16 species in India (Misra, 2007; Maina et al., 1998; Mao et al ., 2011; Gogoi, 2011; Gogoi & Yonzone, 2015), of which 4 are reported from Peninsular India (Misra, 2007). Critical examination of the collected specimens and perusal of the relevant literature (Deori & Hajra, 1975; Liu & Su, 1978; Ansari & Balakrishnan, 1990; Hynniewta et al., 2000; Kumar & Kumar, 2005; Chen & Wood, 2009; Gogoi & Yonzone, 2015; Geiger, 2016) revealed their identity as Oberonia maxima C.S.P.Parish ex Hook.f. and Thrixspermum formosanum (Hayata) Schltr. respectively. They are reported here as new additions to the flora of Peninsular India. Oberonia maxima C.S.P.Parish ex Hook.f., Fl. Brit. India 5: 677. 1888; Deb, Bull. Bot. Surv. India 3(2): 128. 1961; Seidenf., Dansk Bot. Ark. 25(3): 21. 1968; Deori & Hajra, Bull. Bot. Surv. India 17(1–4): 170. 1975; Seidenf., Dansk Bot. Ark. 33(1): 13. 1978; Jain & Mehrotra, Prel. Inv. Orch. India 97. 1984; R.Ansari & N.P.Balak., Orch. Monogr. 4: 22. f. 16. 1990; Hynn. et al. in Hajra & Chatterjee, Orch. Nagaland 224. 2000; A.S.Chauhan in P. Pathak et al ., Orch. Sci. & Com. 93. 2001; C.S.Kumar & P.C.S.Kumar, Rheedea 15(1): 50. 2005; D.L.Geiger, Orchids 85(5): 390. 2016. Type: BURMA, Moulmein, 1869, Parish C.S.P. 287 (holo K000387694 digital image) Fig. 1a & b Epiphytic, pendulous, caespitose herbs. Roots many, pale brownish-white, 2.4–10.5 cm long. Leaves 4–6, pale green, fleshy, distichous, 7.5–15.6 × 1.1–1.6 cm, ensiform, articulate at base, acute at apex, entire. Inflorescence terminal, longer than the leaves, densely many flowered, decurved, compressed and adnate to the reduced uppermost leaf, c. 16.9 cm long, scape c. 4.2 cm long, rachis c. 12.7 cm long. Flowers c. 3.5 mm long, greenish- yellow, sub-sessile or with a short pedicel, closely adpressed to the rachis; floral bracts longer than the pedicel plus ovary, c. 2.3 × 1.2 mm, oblong, RHEEDEA Journal of the Indian Association for Angiosperm Taxonomy Vol. 29(4): 319–322 (2019) ISSN: 0971-2313 (Print edition) ISSN: 2582-2438 (Online edition) https://dx.doi.org/10.22244/rheedea.2019.29.4.05 Additions to the orchid flora of Peninsular India Kaliamoorthy S. & T.S. Saravanan National Orchidarium & Experimental Garden, Botanical Survey of India, Southern Regional Centre, Yercaud, Salem District, Tamil Nadu – 636 602, India. E-mail: bsinoegyercaud@gmail.com