Impatiens glabrata K.M.P.Kumar, Hareesh et Bhaskar, 2016

Prabhukumar, K. M., Hareesh, V. S., Bhaskar, V., Sreekumar, V. B., Nirmesh, T. K. & Balachandran, Indira, 2016, Impatiens glabrata (Balsaminaceae) - A new species from southern Western Ghats, India, Phytotaxa 266 (1), pp. 33-39 : 33-38

Impatiens glabrata K.M.P.Kumar, Hareesh et Bhaskar sp. nov. ( Fig. 1 )

This new taxon is phenotypically and palynologically similar to I. henslowiana but differs in whole plant being sub-glabrous, with the leaves arranged loosely throughout the stem, the lateral sepals glabrous except at apex, the keeled portion of the dorsal petal glabrous, the spur glabrous or sparsely puberulent, and the ovary and capsule glabrous.

Type:— India . Kerala: Palakkad, Singappara, way to Muthikulam Water fall, ± 1350 m, 23 November 2013, K. M. Prabhukumar 7775 (holo-, CMPR).

Terrestrial, perennial shrub, 1.5–2 m long; stem terete, branched, rusty pubescent on young shoots and sparsely on mature stem; internodes 1.5–5 cm long, green, nodes pulvinous. Leaves 5–13 × 3–6 cm, ovate-lanceolate or ellipticlanceolate, acuminate at apex, obtuse to attenuate at base, green, serrate, serration apiculate, rusty pubescent on both surfaces; nerves 7–8 pairs, prominent, rusty pubescent; petiole 1–9 cm long, slender, rusty pubescent, pale green or pale pink. Inflorescence solitary, axillary; pedicel 6–10 cm, pale pink, terete, pubescent. Flower 3–4 × 3.8–4.2 mm, pale pink, few; lateral sepals 10–12 × 4–5 mm, broadly ovate at base, acuminate at apex, glabrous except at apex, pale green; dorsal petal 15–17 × 16–18 mm, orbicular, dorsally keeled, glabrous, pale purple; keel prominent, minutely mucronate at apex, pale green; lateral united petals15–18 × 10–12 mm, two lobed, pale purple; basal lobe 10–12 × 7–8 mm, broadly obovoid, apex minutely notched; distal lobe 9–10 × 5–6 mm, obovate, apex notched; lower sepal 15–17 × 7–10 mm, cymbiform, glabrous, white; spur 2.5–5 cm long, cylindrical, shortly curved, sparsely puberulent, pale pink, two small spiniform appendages on just behind the tip. Stamens 5, connate, 6–7.5 mm long; filaments 3–4 mm long, white, glabrous; anther 3.5–4 × 3–3.5 mm, white or pale rose. Pollen 4-colpate, squarish, 43 × 42 μ, exine sculpturing spinulate and onci prominent, spinules c.34/unit area ( Figure 2 ). Ovary 3 × 2.5 mm, glabrous or sparsely puberulous, pale pink. Capsule 20–25 × 6 mm, ellipsoid, glabrous, tapering on both sides. Seeds 3.5–4 × 2–2.3 mm, obovoid, reticulately pitted, brown. Testa show protruberances or ‘hills’ on the surface, supporting clusters of hyaline bulbous indument with reticulate banding ( Figure 3 )

Phenology:— August–November.

Etymology:— The epithet ‘glabrata’ refers to the nearly glabrous nature of the taxon.

Habitat and Distribution:— The new taxon has been collected only from the type locality in the Muthikulam evergreen forests area. We have observed only one population in this area, occurring between 1300 and 1400 m a.s.l.

Conservation status:— Because this new taxon is found in a highly restricted (15 m 2) area and the only known population contains 25–40 individuals, the taxon could be considered as endangered. Presently there is no threat to the population because of its occurrence in tan protected area. Further explorations may shed more light on the conservation status.

Additional specimens examined (paratypes): — India . Kerala: Palakkad, Muthikulam Water falls, 1350 m, 23 November 2013, V.S. Hareesh, V.B. Sreekumar & T.K. Nirmesh 28202, 28203, 28204 (KFRI!).

Taxonomic affinity:— The new species from Muthikulam shows similarities between I. henslowiana and I. fruticosa Lesch. ex DC. ( De Candolle 1824: 687) . Several populations exhibit intermediate characters between these two species, especially with regard to inflorescence and flower colour, and the identification of these specimens are often mixed up in various herbaria. A sheet at MH (70150) has two plants mounted, one having sub-umbellate inflorescence ( I. fruticosa ) and the other solitary flowers ( I. henslowiana ). It is not known if both these specimens were collected from the same population. During the study, the authors collected a specimen of I. henslowiana from Sispara Ghat of Silent Valley forests with sub-umbellate inflorescence, unusual for the species ( Fig. 3E ). Bhaskar (1975) has described this kind of variation within the species as a good example of ‘atavism’, i.e. the sudden appearance of an evolutionarily old trait. Both I. henslowiana and I. fruticosa have a rosulate arrangement of leaves, prominently hairy leaves, pedicels, lateral sepals and spur, and both are laticiferous. Typical I. henslowiana ( Fig. 3 ) exhibits white flowers (but tend towards dull pink to pale pink), flowers are flat and spreading, and the capsule is densely hairy, whereas in I. fruticosa , flowers are generally pink, with wing petals usually reflexed backwards, and the capsule is glabrous.

The new taxon from Muthikulam exhibits a loose leaf arrangement, solitary flowers and pink flowers are flat and spreading and the capsule is glabrous. Although the entire plant is glabrous or glabrescent except for the young stem and lamina, the lateral sepals show some trichomes at the apex and the spur is glabrous or sparsely hairy. The new species is easily distinguishable from I. henslowiana and I. fruticosa by means of its non-laticiferous stem, glabrescent nature of leaves, pedicels and subglabrous sepals and spurs. Hooker & Thomson (1859) did observe that there are glabrous forms in I. henslowiana with glabrous or pilose capsules under I. henslowiana , and the present species is thus included in this.

The glabrescent form has been collected only from Muthikulam evergreen forest. The authors have surveyed throughout Muthikulam area and did not find any specimen of the typical tomentose form of I. henslowiana . Dr. Anilkumar, who has completed the flora of Attappady and Muthikulam has communicated that he has not come across the presence of the typical tomentose form of I. henslowiana from these localities but has collected it from Mukkali of Silent Valley. Thus it is evident that there is no sympatric distribution of the glabrescent and tomentose forms in the same hill. As the new species is morphologically distinct from the typical tomentose forms of I. henslowiana and I. fruticosa , it forms a distinct geographically isolated population of its own.

Figures

FIGURE 1. Impatiens glabrata sp. nov. A. Habit; B. Close-up of flower; C. Side view of flower; D. Lateral sepal; E. Dorsal petal; F. & G. Lateral united petals; H. Stamen; I. Fruit; J. Fruit split-open; K. Seed. (Photos by K.M. Prabhu & V.S. Hareesh)

FIGURE 2. Impatiens henslowiana A. Habit; B. Single flower (inset: Lateral sepal); C. Abaxial view of flower; D. Fruits; E. Atavism: plant showing sub-umbellate inflorescence. (Photos by K.M. Prabhu & V.S. Hareesh)

FIGURE 3. Impatiens glabrata sp. nov. A.–F. Pollen morphology: 4-colpate, squarish, 43 x 42 μ, exine sculpturing spinulate and onci prominent (Micro photographs by V. Bhaskar)