Impatiens keralensis Saravanan & Kaliamoorthy, 2022

Saravanan, Thokuluva Santharam & Kaliamoorthy, Seventhilingam, 2022, Two new epiphytic species of Impatiens L. (Balsaminaceae) from the southern Western Ghats, India, Phytotaxa 552 (1), pp. 107-114 : 107-110

Impatiens keralensis Saravanan & Kaliamoorthy , sp. nov. ( Figure 1 )

Impatiens keralensis is closely allied to I. modesta Wight (1837: 13) and I. mohana Ratheesh, Sujana & Anil Kumar (2012: 282) in having common characters of a scapigerous tuberous habit, radical leaves, ovate-cordate lamina, unequally trilobed wing petals, and a blunt spur. But differs from I. modesta by having multicellular trichomes on adaxial leaf surfaces (vs unicellular hairs on adaxial leaf surfaces in I. modesta ), short petioles (vs long petioles in I. modesta ), short scapes (vs long scapes in I. modesta ) and 3–6-flowered inflorescence (vs many flowered inflorescence in I. modesta ), white flowers (vs pinkish/whitish in I. modesta ), pedicels longer than flowers, lateral united petals white with yellowish purple papillose at the base of mid-lobe (vs yellowish with a tuft of purple hairs in I. modesta ), and basal lobes emarginate at apex (vs obtuse in I. modesta ); Impatiens keralensis also differ from I. mohana by having multicellular trichomes on adaxial on leaf surface (vs multicellular trichomes on both adaxial and abaxial leaf surfaces in I. mohana ), spinose at margins (vs absence of spinose in I. mohana ), glabrous petiole (vs trichomatous in I. mohana ), and white flowers (vs deep pinkish in I. mohana ) ( Table 1 ).

Type:— INDIA. Kerala: Wayanad District, Kurichiarmala Reserve Forest , 11º36’1”N, 75º57’59”E, 1100–1320 m, 11 December 2019, Saravanan & Kaliamoorthy 136020 (holotype MH!) .

Scapigerous, tuberous acaulescent, epiphytic herbs, 5–10 cm tall. Tubers sub-globose, 0.8 × 0.7 cm, brownish white. Stem-less. Leaves radical, 2-3 per tuber, 1.5–4.2 × 1.0– 3.5 cm, broadly ovate to cordate in outline, deeply cordate to auriculate-cordate at base, crenate-serrate and spinose at margins, obtuse at apex, adaxially covered with multicellular white trichomes, greenish; abaxially glabrous, pale purplish green, with 3-4 pairs of lateral nerves; petioles 1.9–3.3 cm long, pale reddish with purple streaks, glabrous. Inflorescence racemose; peduncle longer than the leaves, ca 6.5 cm long, 3–6-flowered, glabrous, terete, pale reddish with purple streaks; Flowers 0.6–0.8 cm across, white; bracts 0.3 × 0.1 cm, slightly falcate, obtuse at apex, glabrous, green with purple streaks, thick and fleshy; pedicel longer than the flowers, ca 1.3 cm long, filiform, pale reddish with purple streaks, glabrous; lateral sepals 0.2 × 0.1 cm, obliquely oblong, obtuse at apex, glabrous; dorsal petal ca 0.2 × 0.2 cm, concave, orbicular to reniform, obtuse at apex, forming a hood above the androecium, dorsally humped at base, glabrous; wing petals free, unequally 3-lobed, 1.4–1.5 × 0.6–0.8 cm, white with a tuft of deep yellowish purple papillose at the base of mid-lobe; basal lobe ca 0.7 × 0.2 cm, oblong, broadest at the middle, slightly up-curved, emarginate at apex; mid-lobe ca 0.5 × 0.2 cm, oblong, obtuse to truncate at apex; distal lobe ca 0.7 × 0.2 cm, oblong, obtuse to truncate at apex; dorsal auricle absent; lower sepal ca 0.3 × 0.2 cm, ovate, obtuse at apex, concave, white, 0.1 cm deep, glabrous; spur ca 0.3 × 0.1 cm, straight, white, glabrous; stamens ca 0.2 cm long, curved; filaments ca 5, 1.3 mm long, narrow and free at base, fused and broad at apex, light pink to white; anthers 5, ca 1.0 × 0.4 mm, white, cohering above the pistil; pistil ca 1.2 × 0.3 mm; ovary broadly obclavate to ellipsoid, glabrous. Capsules 0.5–0.8 cm long, broadly ellipsoid, greenish, glabrous; seeds minute, comose with tuft of hairs at both ends.

Phenology:—Flowering & fruiting: August–November.

Ecology:—Growing on moss covered wet tree trunks in evergreen forests, along with Impatiens veerapazhasii Ratheesh, Sujanapal & Meera (2011: 154) , Oberonia bicornis Lindl. (1830: 16) and Oberonia swaminathanii Ratheesh, Manudev & Sujanapal (2010: 713) , at an elevation of 1310 m.

Conservation Status:— Impatiens keralensis is only known from the type locality with about 10–12 mature individuals. The population is well conserved within the boundaries of protected forest areas. However, considering the lesser number of individuals in a single population size distributed in an area of hardly 0.3 km, the species described here is assessed as Critically Endangered (CE) by applying the criterion d ( IUCN 2019).

Etymology:—The species is named after the Kerala state, India, where the type locality is present.

Notes:— Impatiens keralensis is also allied to I. dendricola C. E. C. Fisch. (1935:157) , in having a tuberous scapigerous epiphytic habit, radical leaves, flowers in racemose scapes, white flowers and presence of spur, but differs in the size and shape of the bract (slightly falcate in Impatiens keralensis vs ovate in I. dendricola ), lateral sepals (obliquely oblong in Impatiens keralensis vs asymmetrically ovate in I. dendricola ), dorsal petal (obtuse at apex in Impatiens keralensis vs retuse at apex in I. dendricola ), wing petals (papillose at the base of mid-lobe in Impatiens keralensis vs hairs at the base in I. dendricola ), spur (straight in Impatiens keralensis vs clavate in I. dendricola ), and dorsal auricle (absent in Impatiens keralensis vs present in I. dendricola ).

Figures

FIGURE 1. Impatiens keralensis A) Habit. B) Abaxial view of leaf. C) Flower. D) Lateral view of flower. E) Papillose close-up view on wing petals. F) Bract. G) Dorsal petal. H) Lateral sepal. I) Wing petals. J) Lower sepal and spur. K) Androecium. L) Fruit. (Photographs by T. S. Saravanan)