Impatiens courtallensis Ramasubbu & Pandurangan, 2015

Ramasubbu, R., Manikandan, G., Mehalingam, P. & Pandurangan, A. G., 2015, Impatiens courtallensis (Balsaminaceae), a new species of Impatiens from Western Ghats, Tamil Nadu, India, Phytotaxa 203 (2), pp. 199-204 : 201

Impatiens courtallensis Ramasubbu & Pandurangan sp. nov.

Type: — INDIA, Tamil Nadu, Tirunelveli District, Courtallum hills (Agasthyamalai) way to Mylodai estate, 8 o 54’38.114 N ; 77 o 15’22.495 E ; 788.24 m msl, 13 September 2013, R. Ramasubbu & G. Manikandan, GU 0219 (holotype TBGT!, isotype Gandhigram University Herbarium) .

Annual, succulent, erect, glabrous herb, 25–30 cm high; stems cylindrical, often branched with purple dots, branches erect, nodes slightly swollen, internode elongate, 3–3.5 cm. Leaves opposite decussate, 3–4.5× 1–1.5 cm long, shortly petiolate, petiole 0.5 mm, coriaceous, linear, acuminate, entire, base truncate, slightly cordate, reflexed upwards, leaf margin distinctly serrate, leaf blade 1–2mm, pair of extrapetiolar glands, minute, subulate, pointed, purple. Inflorescence binate, 2 per angle (4 per node), rarely 2–3 together, flowers simple, pedicellate, axillary, 3–4 mm across, milky white; pedicels 0.5–1.0 cm long. Sepals: llateral sepals 2, linear, acuminate, 2–4 mm long, prominently nerved, milky white. lower sepal boat shaped, tip of the lower sepal outwardly curved, 3–4× 1–2 mm, horizontal, spur minute, 0.5 mm or punch-like structure at base or gibbous, Petals: dorsal petal orbicular, 2–3 × 1.5–2 mm, recurved, dorsally keeled, apiculate, lateral united petals stipitate, deeply clawed, 2 lobed, 3–4 mm long, basal lobe small, oblong, distal lobe round or spherical, dorsal auricle prominent, blunded; Ovary elongated, 2mm long, Fruit: capsules small, ovoidal, turgid, 5–8 × 2–3 mm, acute, beaked, 3–5 seeded; seed round with prominent caruncle with minute hairs, compressed, 1–2× 0.5–1 mm, smooth, black, shining.

Etymology: —The species was collected from the floristically important Courtallum hills, a part of Agasthyamalai Biosphere Reserve in Western Ghats, Tamil Nadu. Therefore, the specific epithet has named for its place of occurrence.

Distribution: —Rare in the hill tops at 788.24 m msl.

Additional specimens examined (paratype): — INDIA, Tamil Nadu, Tirunelveli District, Courtallum hills (Agasthyamalai) way to Mylodai estate, 8 o 54’38.114 N ; 77 o 15’22.495 E ; 788.49 m msl, 30 October 2014, R. Ramasubbu & G. Manikandan, GU 0368 (Gandhigram University Herbarium) .

Flowering and Fruiting: —August to November.

Conservation status: — Impatiens courtallensis is assessed as critically endangered according to the IUCN ( IUCN 2010). There were only two populations (32±9 individuals per populations) observed within 0.6 km. The habitat of the species was severally affected by landslide.

Notes:— Impatiens courtallensis grows as upright in the open grasslands and in grassy slopes of rocks nearby streams and marshy areas. This species of Impatiens is associated with Aristida funiculata Trin. & Rupr. , Themeda triandra Forssk. , Chloris dolichostachya Lag. , Eriocaulon truncatum Buch. -Ham. ex Mart., Fimbristylis dichotama (L.) Vahl, among others. Impatiens courtallensis is closely allied to I. herbicola and I. munnarensis in general floral structure but it differs in having its characteristic features ( Table 1). Baskar (2012) studied the pollen morphology of I. herbicola and confirmed as 4-colpate with more or less radial. But the pollengrains of I. courtallensis were identified as 4-colpate with strictly squarish and 16–18μm size. Ramasubbu and Pandurangan (2014) studied the pollengrains of Impatiens munnarensis as purple coloured and radial. Bhaskar (2012) reported the pollengrains of I. herbicola as yellow colored. However, the colour of the pollengrains of I. courtallensis were observed as milky white. Therefore, the species has greater variation in the colour, structure and ornamentation of pollengrains with respect to I. herbicola and I. munnarensis .