Impatiens achudanandanii Kumar V.S.A., M.G. Govind & Sindhu Arya, 2021

Arya, Sindhu, Govind, Murugan Govindakurup, Suresh, Veerankutty, Vishnu, Walsan Kalarikkal & Kumar, Venugopalan Nair Saradamma Anil, 2021, Three new species of Impatiens (Balsaminaceae) from southern Western Ghats, Kerala, PhytoKeys 180, pp. 157-171 : 157

Impatiens achudanandanii Kumar V.S.A., M.G. Govind & Sindhu Arya sp. nov.

Figs 1 , 2 , 7

Type.

India. Kerala, Thiruvananthapuram, Kallar forest area, along the streams of highland 8.7599°N, 77.1169°E, 1200 m a.s.l., 26 August 2019, Kumar V.S.A .., M.G. Govind & Arya.S, 1056 (holotype TBGT!, isotype MH! CALI!) .

Diagnosis.

Impatiens achudanandanii is similar to I. courtallensis Ramasubbu, from which it differs by the color of the flowers (whitish-creamy with yellow spot at throat in I. achudanandanii vs. milky-white in I. courtallensis ), the shape of the fruit, the shape, number and hairiness of the seeds (ovoid, 2-3 seeded fruit and seed glabrous in I. achudanandanii vs. fusiform, 3-5 seeded and with minute hairs in I. courtallensis ), the shape of the dorsal petal (ovoid-circular in I. achudanandanii vs. orbicular, recurved in I. courtallensis ), the shape of the lateral united petals (basal lobe ovate-obovate, distal lobe round in I. achudanandanii vs. basal lobe oblong, distal lobe spherical in I. courtallensis ), the shape of lower sepal (saccate and tip pointed in I. achudanandanii vs. boat shaped and tip outwardly curved in I. courtallensis ) and the size and color of the pollen grains (10 × 16 µm whitish-yellow in I. achudanandanii vs. 16 × 18 µm squarish, milky-white in I. courtallensis ).

Description.

Annual, succulent, straggling, glabrous herb, 15-20 cm high; stems terete, unbranched with purple dots, nodes slightly swollen, internode elongated, 1-1.5 cm. Leaves opposite, decussate, 2-2.5 × 1-1.2 cm long, shortly petiolate, petiole 0.5 mm, coriaceous, linear, acuminate, entire, base truncate, slightly cordate, reflexed upwards, leaf margin distinctly serrate, leaf blade 1-2 mm, extra petiolar glands absent. Inflorescence 2-3 together, flowers simple, pedicellate, axillary, 2-3 mm across, whitish-creamy with yellow spot on the throat; pedicels 0.5-0.8 cm long. Sepals- lateral 2, linear-lanceolate aristate, 0.5-1 mm long, faintly nerved, white. Lower sepal boat shaped, tip of the lower sepal pointed, 1.0-1.2 × 0.5-0.8 mm, horizontal, spur minute, 0.2 mm, yellow. Petals-dorsal ovate, 1.5-1.8 × 0.5-0.8 mm, beaked, dorsally keeled, apiculate, lateral united petals stipitate, not clawed, 2 lobed, margin smooth 1-1.5 mm long, basal lobe small, ovate, distal lobe round, dorsal auricle not prominent, end sharp. Ovary ovoid, 0.5 mm long. Fruit: capsules small, ovoid, turgid, 3-5 × 2-3 mm, acute, red shaded, 2-6 seeded; seed hexagonal, smooth, compressed, 1-2 × 0.5-1 mm. Pollen grains 10 × 16 µm whitish-yellow.

Etymology.

Impatiens achudanandanii is named in honor of Mr. V.S. Achudanandan, former Chief Minister of the state of Kerala for his ardent efforts in conservation of the pristine environment of Western Ghats, especially Mathikettan shola.

Phenology.

August to November.

Distribution and habitat.

Impatiens achudanandanii is distributed in the highlands above 1200 m. So far, the specimen has been observed only in the type locality. The populations are scattered and under the threat of grazing and other anthropogenic pressures. The plants are found to grow associated with seasonal ditches near the shade of huge rocks. Species of Eriocaulon , Utricularia reticulata and Drosera indica were found to grow in the nearby vicinity of this species

Conservation status.

Impatiens achudanandanii is assessed as Critically Endangered (CE) according to the IUCN categories using the criterion d ( IUCN 2019). There were only three to four populations (10-15 individuals per population) observed within 1 km. The habitat of the species was severely affected by stamping of wild elephants and land-slides.

Other notes.

Impatiens achudanandanii belongs to the section Uniflorae under the subgenus Uniflorae Impatiens . characterized by ellipsoidal shape of seed and capsules that are short and conspicuously turgid at middle. The new species resembles I. courtallensis , a species reported from Courtallam hills of Tamil Nadu and also I. herbicola , a common high altitude species. The shape of dorsal petal, minute size of flower and the presence of spur distinguished the newly described species from its allied taxa. Impatiens achudanandanii is distinct from its other allied taxon I. herbicola with respect to spur (present in I. achudanandanii vs. absent in I. herbicola ), color of the flower (whitish-creamy with yellow spot at throat in I. achudanandanii vs. bluish or yellowish in I. herbicola ), size of the flower (2-3 mm in I. achudanandanii vs. 5-9 mm in I. herbicola ), shape of the fruit (ovoid 2-6 seed in I. achudanandanii vs. gibbously ovoid with many seeded in I. herbicola ), shape of lateral united petals (basal lobe obovate-ovate in I. achudanandanii vs. oblong in I. herbicola ), shape of dorsal petal (circular, faintly keeled in I. achudanandanii vs. orbicular and thickly keeled in I. herbicola ) as well as size and color of the pollen (10 × 16 µm whitish-yellow in I. achudanandanii vs. 21 × 23 µm, yellow in I. herbicola ).

Specimen examined.

Impatiens achudanandanii India. Thiruvananthapuram, Kallar. 22 August 2019, Arya & Kumar V.S.A. 1057 (MH!, TBGT!); 10 September 2019. M.G. Govind 957 (TBGT!). Impatiens herbicola India. Thiruvananthapuram, Kallar. 22 August 2019, Kumar V.S.A. & Arya 1037 (TBGT!); 4 September 2019, Arya & Kumar V.S.A. 1097 (TBGT!).

Figures

Figure 1. Impatiens achudanandanii A habit B twig C flower D fruit E side view of flower. Photos by Govind.

Figure 2. Impatiens achudanandanii A habit B flower (front view) C flower (lateral view) D petals E dorsal petal F lateral petals G lower sepal H lateral sepal I stamen J pollen K gynoecium L fruit M seed. Illustrations by V. S. Anilkumar.

Figure 7. Distribution map of Impatiens achudanandanii, Impatiens danii and Impatiens shailajae.