Impatiens yinyinkyii M.M. Latt, B.B. Park & Nob. Tanaka, 2023

Latt, Myo Min, Tanaka, Nobuyuki & Park, Byung Bae, 2023, Two New species of Impatiens (Balsaminaceae) from Myanmar, Phytotaxa 583 (2), pp. 141-152 : 142-146

Impatiens yinyinkyii M.M. Latt, B.B. Park & Nob. Tanaka , sp. nov. ( Figs. 2 & 3 )

Type: — MYANMAR. Sagaing Region: Htamanthi Wildlife Sanctuary , along high humid rocky stream, ca. 138–159 m elevation, N 25°16’25” and E 95° 20’ 08 on 29 November 2020, Myo Min Latt MY5938 (holotype-RAF, isotype-TNS) .

Diagnosis: Impatiens yinyinkyii is morphologically similar to I. masonii Hook. f. but can be distinguished by having asymmetric flowers with three dark purple blotches in center of flower, specifically at base of dorsal and upper petals of lateral united petals, round apex dorsal petals, monochasial simple cymose inflorescence, lanceolate bract, pink anther, longer incurved spur and ovate and compressed seed ( Table 1 ).

Perennial herb, terrestrial or lithophyte. Stems up to 60 cm heigh, erect, cylindrical, tapering up, glabrous, dull purple, nodes swollen, up to 7 mm in diameter, internodes glabrous, up to 3 am long, up to 5 cm in diameter, root fibrous at up to 5 th node, having small white tubers, sometimes node touch ground produce small root, very branching, succulent. Leaves 0.8–1 × 10.5–11 cm, opposite decussate arranged, glabrous, linear, tip acuminate, base attenuate, margin serrate, antrorse bristles at the top of teeth, venation clear, up to 6 veins, 45 degrees with mid-vein, tapering to margin, abaxial surface dark green, abaxial surface pale green, petiole 7 mm long, glabrous. Inflorescence axillary, monochasial simple racemes, 5 cm long, 2 flowered, peduncle glabrous, purple, 2 cm long. Flowers zygomorphic, pinkish purple with dark purple blotches at the center, glabrous; pedicels slender, up to 1.5 cm long, ca. 1 mm in diam., dull purple. Bracts ca. 1 × 2 mm, narrowly lanceolate, apex acuminate, base cuneate, green, glabrous. Lateral sepals 2, lanceolate, transparent, green, dull purple blotch at base on abaxial surface, 1 × 4 mm, acuminate tip, broad base. Lower sepal navicular, pale purple, broadly elliptic mouth, white with dark purple blotch at base, acuminate apex, 5 × 7 mm, yellow base, spur curved, glabrous, tapering, up to 4.5 cm long

Dorsal petal orbicular, 9 × 9 mm, curved like boat, 4 mm deep, pinkish purple with dark blotch at base, 2 crests on abaxial surface, margin entire, apex and base rounded. United lateral petals connate, asymmetric, lobes free; upper petals 7 × 8 mm, orbicular, apex rounded to truncate, pinkish purple with round dark purple block at base; lower petals ovate, asymmetric pinkish purple, 8 × 10 mm, apex acute, oblique, base rounded, auricle yellow with claw or projection, 1 mm long, vein on abaxial surface, overlap and connect to upper petal with whitish petioloide auricle. Androecium Stamens pink, 3 mm long, 1 mm width, narrow base, green, 5 lobed, persistent above ovary after over flowering. Gynoecium Ovary green, 3 mm long, 1 mm in diameter, glabrous. Fruits fusiform dehiscent capsules, asymmetric, slightly curved, tapering both ends, 1.2 cm long, up to 5 mm in diameter, glabrous, 5 lobes, dark green upper 3 lobes, pale green lower 2 lobes. Seeds ovoid like sesame seed, compressed, apex pointed, round base, brown, covered by white nets, ca. 1.5 mm long, up to 6 per capsule

Habitat and ecology: Impatiens yinyinkyii grows on the ever-moist rock and rocky wall of the perennial stream under the sunlight. It is light demander but very sensitive to high temperature and drought. This species is very common and many populations can be found on the rock along streams throughout the Htamanthi Wildlife Sanctuary.

Phenology: Flowering in November to January before summer season.

Distribution: Myanmar. Thus far known only from the type locality.

Vernacular name: “Yin Yin Kyi Dan-pan” (proposed here). “Dan-pan” is a local name of Imapatiens in Myanmar.

Etymology: The specific epithet is an honor to Yin Yin Kyi (1947–2021), a Myanmar taxonomist at Forest Research Institute, for her contribution to the Myanamar local flora. She published “A checklist of the trees, shrubs, herbs and climbers of Myanmar ” by revising the original works by J. H. Lace “List of trees, shrubs, herbs and principal climbers, etc. recorded from Burma ” in cooperating with the Smithsonian Institution.

Note: Impatiens yinyinkyii is assignable to subgenus Impatiens , sect. Uniflorae Hook.f. & Thomson based on its fascicled inflorescence, and short fusiform capsules.

IUCN Red Data Category: This species seems to prefer wet and cold rock along the bank of the stream. It cannot survive on alluvial sediment and dry rock. We observed that some died off because of cover by sediment and camping along the stream. In addition to such impacts, cutting the trees along the stream should be prohibited to reduce the soil erosion and to regulate riparian ecosystem. Therefore, based on the latest IUCN criteria, Impatiens yinyinkyii is proposed to be Near Threatened (NT) ( IUCN, 2022).

Key different characteristics between Impatiens yinyinkyii and I. masonii are mentioned in Table.1 .

Figures

FIGURE 2. Impatiens yinyinkyii; A. growing on ever-moist rock wall of stream, B. roots with small tubers, C. front view, D. dorsal view, E. side view of flower and F. inflorescences and leaves arrangement.

FIGURE 3. Detail floral parts of Impatiens yinyinkyii; a–b. adaxial and abaxial surfaces of united lateral petals, c–d. adaxial and abaxial surfaces of upper lateral petals e–f. adaxial and abaxial surfaces of lower lateral petals, g–h. adaxial and abaxial surfaces of dorsal petals, i–j. lower sepal, k. pair of lateral sepal, l. gynoecium with lateral sepal, m. gynoecium at the center of floral parts, n. ovary covered by anther under microscope, o. peduncle, floral bracts and stalk, p. ovary after over flowering, q–s. unmatured, matured and broken fruit and t. seed.