Habenaria osmastonii Karthig., Maina, Sumathi, Jayanthi & Jalal 2014, sp. nov.
Creators: name: Karthigeyan, K.
name: Maina, V.
name: Sumathi, R.
name: Jayanthi, J.
name: Jalal, J. S.
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Asparagales
Orchidaceae
Habenaria
Habenaria osmastonii

description: Habenaria osmastonii Karthig., Maina, Sumathi, Jayanthi & Jalal sp. nov. (Figs. 1–3)
Habenaria osmastonii is similar to H. richardiana Wight (1851:5) but differs by having radical leaves, fewer and smaller flowers (3–5 flowers ca. 1 cm across), shallowly denticulate, falcate lip side lobes and a lip midlobe which is slightly longer than the side lobes.
Type: — INDIA, South Andaman, Rutland Island, Dyer Point, 11 October 1905, Osmaston 21 (holotype CAL!).
Terrestrial herbs, 10–20 cm tall. Tuberoids 1–2, oblong, 1.5–2.0 cm long, bearing filiform roots. Leaves radical, 3–5, crowded at base of stem, broadly lanceolate, 2.5–5 × 0.8–1.2 cm, obtuse at apex, entire along margin, sessile. Inflorescence a raceme, subdense, 3–5-flowered, bearing 3–5 leaf-like sterile bracts; sterile bracts lanceolate, 0.6–2.0 × 0.3 cm, acuminate. Flowers white, ca. 1 cm across; pedicel with ovary c. 1.5 cm long; ovary twisted. Floral bracts lanceolate, ca. 6 × 2 mm, acute at apex, much shorter than the ovary. Sepals and petals subsimilar; dorsal sepal broadly ovate, ca. 6 × 3 mm, concave, hooded, with slight green tinge, 2-nerved; lateral sepals spreading, obliquely ovate, ca. 6 × 3 mm, acute at apex, white, 2–nerved. Petals slightly falcate, ovate-lanceolate, ca. 7 × 3 mm, acute at apex, white, 3-nerved, forming hood together with dorsal sepal. Lip ca. 15 × 9 mm, 3-lobed; side lobes subrhombic, ca. 7 × 5 mm, slightly falcate, irregularly denticulate at apex, 3-nerved, midnerve further divided in 4 small nerves towards apex; midlobe linear, ca. 9 × 3 mm, obtuse at apex, 3-nerved, longer than the side lobes; spur white, 3.0– 3.2 cm long, somewhat thickened below the middle, subclavate, acute to subobtuse at apex. Column white, ca. 3.5 mm long, emarginate at apex; anther cells widely separate, anther tubes upwards. Stigmatic process short, white, slightly concealing the mouth of the spur. Pollinia 2, ca. 1 mm across, yellow. Capsule not seen.
Flowering: —July–October.
Distribution: — INDIA: Rutland Island in South Andaman (Fig. 2).
Habitat & Ecology: —The new species is distributed in Rutland Island of South Andaman, India. It grows in stunted evergreen forest on the hill slopes above 300 m, in association with Carex indica Linnaeus (1771: 574) and Oryza meyeriana (Zoll. & Moritzi, 1805) Baillon (1894: 166).
Additional specimen examined: — INDIA, South Andaman, Rutland Island, Mount Ford, 15 July 2003, K. Karthigeyan 6081 (Paratype CAL!).
Etymology: —The specific epithet is named after Bertram Beresford Osmaston (1867–1961), who made the first collection of this species from Rutland Island in South Andaman.
Conservation Status: —The species is extremely rare. Only less than twenty individuals were sighted at a single locality in Rutland Island. More exploration is needed in similar habitats to assign the exact threat category. However, based on its small geographical range it is provisionally assessed as Critically Endangered B 1a using the criteria of the IUCN redlist guidelines 2012 (version 3.1).
Note:—This species can be readily distinguished from Habenaria andamanica which is found in the same area by the basal leaves and the lip shape. It shows an affinity to the South Indian H. richardiana; the distinguishing characters of H. osmastonii and H. richardiana are provided in the following Table 1.
description: Published as part of Karthigeyan, K., Maina, V., Sumathi, R., Jayanthi, J. & Jalal, J. S., 2014, Habenaria osmastonii (Orchidaceae), a new terrestrial orchid from the Andaman Islands, India, pp. 150-154 in Phytotaxa 166 (2) on pages 151-153, DOI: 10.11646/phytotaxa.166.2.7, http://zenodo.org/record/5138358