Impatiens jacobdevlasii Herath, C. Bandara & Gopallawa, 2022

Bandara, Champika, Herath, Sanath Bandara, Gopallawa, Bhathiya & Attanayake, Achala, 2022, Impatiens jacobdevlasii (Balsaminaceae), a new species from Knuckles massif of Sri Lanka, Phytotaxa 543 (3), pp. 181-187 : 182-186

Impatiens jacobdevlasii Herath, C. Bandara & Gopallawa sp. nov. ( Figs. 1‒3 & 4 I–P )

Type:— SRI LANKA, Central Province, Kandy District, Dothalugala Mountain , on the ground among rocks and mosses along stream, 1375 m a.s.l., 13 October 2018, Sanath Herath & Champika Bandara 2018-05. (holotype PDA!) ; Central Province, Kandy District, Thangappuwa –Alugallena nature trail, along shady embankments of the trail, 1512 m a.s.l., 02 June 2019, NBS/2019/ OL / TGP/009. (paratype PDA!) .

Diagnosis: Impatiens jacobdevlasii morphologically similar to I. truncata but differs by having pinkish or purplish color flowers with pink margin, bilobed upper petal of lateral united petals and yellow color centre blotch, linearlanceolate lateral sepal, 4–6 lateral nerve pairs, abaxially scattered pubescent and adaxially glabrous lamina.

Description: Herb, Perennial, 30–60 cm tall; stem pale greenish, swollen at nodes, cylindrical, glabrous. Leaves simple, spirally arranged, lower part often naked and often crowded towards apex of stem, petiolate; Petiole ca. 2–3 cm long, glabrous, pale green; stipule minute, ca. 0.5–1 mm. Lamina lanceolate or elliptic-lanceolate, 2–8 (–10) × 1.5–3.5 (–4.5) cm, base subattenuate, acuminate at apex; adaxially dark green color with scattered minute hairs, abaxially pale green, glabrous, margin crenate or serrate with a single narrow tooth; setulose in between marginal teeth. Lateral nerves in 4–6 (–7) pairs, sub-opposite, prominent. Flowers solitary in the upper leaf axils, simple, pale pinkish or purplish with pink margins and rarely white. Peduncle 2.5–3.5 cm long, thin, pale green, scattered pubescent. Lateral sepals 2, linear-lanceolate, 3.5–4 × 0.7–0.9 mm, glabrous, slightly curved, pale green, pinkish towards apex, margins entire. Lower sepal 13–15 × 6–8 mm, navicular, white externally and internally with yellow patch at the centre, 1 mm long mucronate at apex; spur 3–4 mm long, pale yellowish, straight, cylindrical. Dorsal petal cucullate, 9–10 × 6–7 mm, concave, dorsally with a narrow crest terminating in a short pointed appendage, ca. 1.5–2 mm. Lateral petals united, 20–25 × 8–10 mm, 2-lobed; base of united lateral petals with yellowish blotch, upper petals about one-third the size of the lower petals; upper petal 7–9 × 5–7 mm, apex equally bilobed, pinkish or purplish shade towards apex and yellowish blotch in the centre; lower petal 15–18 × 8–10 mm, semi-oval, often notched at apex, base and inner margin of the distal lobes with minute pinkish or whitish ridge of papillae. Androecium 4–5 × 2 mm, glabrous, white. Stamens 5, connate, surrounding gynoecium. Filament ca. 1 mm, glabrous, white; style glabrous, ca. 0.5 mm long. Capsule green, 10–12 × 5–7 mm, broadly fusiform, 5-angled, pilosulose, apex acute, rostellate, fleshy; Seeds 1–4, 5–7 × 3–5 mm, obovoid, slightly compressed.

Distribution: Impatiens jacobdevlasii is known from Dothalugala Mountain and Thangappuwa area in Knuckles massif of Sri Lanka.

Habitat and ecology: Impatiens jacobdevlasii is known only from two locations in South-eastern region of Knuckles massif. Small populations of this species are distributed in the reported area. The overall number of mature individuals is estimated as ˂ 80 in the both populations from field observation. Both locations are belongs to lower montane evergreen forests at elevation of 1300–1500 m a.s.l. ( Gunatilleke and Ashton 1987). One population was recorded from Dothalugala Mountain (1375 m a.s.l.) with ˂30 individuals and other from Thangappuwa (1512 m a.s.l.), population comprise with 2–3 subpopulations; 10–15 individuals per each. The new species is usually found on the ground among mosses and rock boulders along streams. This species mostly refer well-shaded forest cover and associated species are Rhynchoglossum notonianum (Wall) B.L. Burtt (1962: 170) , Strobilanthes sexennis Nees (1837: 312) , Ophiorrhiza pectinata Arnott (1836: 338) , Phaius wallichii Lindle (1831: 46) and Begonia malabarica Lamarck (1785: 393) .

In the wild, this new species facing threat of extinction due to the low number of plants representing the entire population, population decline and its limited distribution. Dothalugala population shows significant decrease through the 2016–2022 period, approximately 80% of the population.

The habitats of the new species associated with existing nature trails in Knuckles mountains ( Bambaradeniya & Ekanayake 2003). Dothalugala population located near a stream in existing Deanston–Dothalugala nature trail and Thangappuwa population located in wet, rocky surfaces along the existing Thangappuwa–Alugallena nature trail. Any situation in road clearing, weeding, constructions or maintaining, authorities should focus the attentions for management and further conservation attempts on this new species.

Thus, I. jacobdevlasii has a great potential for horticultural applications due to its wide color range of flowers ( Fig. 3 ) and few plants were cultivated at Royal Botanical Garden, Peradeniya, Sri Lanka.

Phenology: Flowering and fruiting all around the year.

Etymology: The specific epithet is named in honour of Dr. Jacob de Vlas, a Dutch biologist and the author of the tri-volume series of the ‘Illustrated field guide to the flowers of Sri Lanka’ in 2008–2019 documenting over 3000 native and introduced species of the Island. The common name for the species is Vlas’s balsam.

Proposed IUCN conservation assessment: Based on current knowledge, the Extent of Occurrence (EOO) and Area of Occupancy (AOO) was estimated using GeoCAT ( Moat 2007) as ~ 2 km 2 and 12 km 2 respectively. From the available data, we classify I. jacobdevlasii as ‘Critically Endangered’ (CR: B1+B2b (ii,iii,v); C2a (i,ii); D) in accordance with IUCN guidelines ( IUCN 2019).

Additional specimens examined: SRI LANKA. Impatiens truncata :—MATALE DISTRICT : Midlands Estate to Laggala , 700 m a.s.l., Nov. 1978, Grey-Wilson & Silva 3002 ( PDA!); Matale to Illukkumbura road, July 1974, Sumithraarachchi 418 ( PDA!). KANDY DISTRICT : Corbet’s Gap , Rangala to Looloowatte (Loolwatte), 1300 m a.s.l., September 1969, Grupe 237 ( PDA!); Kalupahana Forest, Knuckles Mts., 1250 m a.s.l., July 1973, Jayasuriya & Balasubramaniam 1220 ( PDA!); Hantana, s. coll. C. P . 2426, pro parte (PDA!);. NUWARA ELIYA DISTRICT: between Ramboda and Nuwara Eliya, 1500 m a.s.l., Nov. 1978, Grey-Wilson & Wickramasinghe 3035 ( PDA!); Pattipola to Farr Inn , Horton Plains, Nov. 1973, Sohmer, Jayasuriya & Eliezer 8523 ( PDA!). Impatiens jacobdevlasii :— KANDY DISTRICT: Thangappuwa–Alugallena nature trail, Knuckles Mt., 1540 m a.s.l., December 2019, Champika Bandara & Shashee Dilrukshi 2019-13 ( PDA!)

Figures

FIGURE 1. Impatiens jacobdevlasii; A. Mature individuals in the natural habitat, B. front view of the flower, C. Lateral view of the flower, D. Rear view of the flower, E. Capsule. Photographs by Sanath Bandara Herath (A), Bhathiya Gopallawa (B–E).

FIGURE 2. Impatiens jacobdevlasii; A. Plant habit (holotype: Sanath Bandara & Champika Bandara 2018-05), B. Developing flower bud, C. Front view of a flower, D. Lateral view of the flower, E. Dorsal petal, F. Lateral view of dorsal petal, G. Lower sepal, H. Lateral sepals, I. Lateral united petal, J. Androecium, K. Mature capsule. Illustrations by Champika Bandara.

FIGURE 3. Color variations of Impatiens jacobdevlasii flowers; A. White color, B. Light purple color, C. Light pink color, D. Deep pink color. Photographs by Bhathiya Gopallawa.

FIGURE 4. Comparison of Impatiens truncata (A–H) with I. jacobdevlasii (I–P). (A, I). Front view of flower, (B, J). Dorsal petal, (C, K). Lateral sepals, (D, L). Lateral united petals, (E, M). Pedicel with androecium, (F, N). Front view of lower sepal, (G, O). Lateral view of the lower sepal, (H, P). Capsules. Photographs by Bhathiya Gopallawa.