Sunday, February 5, 2023

[Botany • 2023] Impatiens yinyinkyii & I. horizontalis (Balsaminaceae) • Two New Species from Sagaing, northwestern Myanmar

 Impatiens horizontalis  M.M.Latt, B.B.Park & Nob.Tanaka, 

in Latt, Tanaka & Park, 2023. 
Impatiens yinyinkyii M.M.Latt, B.B.Park & Nob.Tanaka and I. horizontalis M.M.Latt, B.B.Park & Nob.Tanaka (Balsaminaceae) are described and illustrated. Those new species were discovered in Htamanthi Wildlife Sanctuary, northwestern Myanmar. Description, photographic data as well as the comparative characters with their similar species are provided. Impatiens yinyinkyii is similar to I. masonii Hook.f., but differs in having three dark purple blotches in center of flower, specifically at base of dorsal and upper petals of united petals. Impatiens horizontalis resembles I. stenantha Hook.f., I. prostrata Hook. f., I. repens Moon, I. procumbens Franch and I. reptans Hook. f. in having larger, glabrous and elliptic to lanceolate leaves, serrate margin with antrorse bristles, deeply bucciniform lower sepal, twisted spur with abruptly capitate tip, linear ovary, spheroid seed and finally uncommon conspicuous stout stem which is horizontally creeping.

Keywords: Burma, Impatiens yinyinkyii, Impatiens horizontalis, new taxon, Sagaing

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.

Impatiens yinyinkyii
M.M. Latt, B.B. Park & Nob. Tanaka, sp. nov. 

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). 

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.

 Impatiens horizontalis;
 A. horizontally growing on gravel stony island in a stream, B. Leave margin, C. creeping on gravel stony habit, D. inflorescences E. gold mining and F. leave arrangement, stem and peduncle of inflorescences.

Impatiens horizontalis M.M. Latt, B.B. Park & Nob. Tanaka, sp. nov.

Diagnosis: Impatiens horizontalis is morphologically similar to Impatiens stenantha Hook.f. but can be distinguished by being horizontally creeping stem on the surface of gravel soil along the stream, elliptic to linear leaf, coriaceous, serrate margin with bristles, axillary inflorescence and pure golden yellow flower without marks; in spite of similar creeping habit, it is distinguished from I. prostrata Hook. f. by having narrowly elliptic to linear leaf, serrate, antrorse bristle between teeth, glandular stipulate, twisted spur with abruptly capitate tip, linear and glabrous ovary and spheroid, ex-arillate, glabrous seed; from I. repens Moon by having not succulent and stout stem and racemose inflorescence; from I. procumbens Franch and I. reptans Hook. f. having not erect stem and branches, narrowly elliptic to linear, glabrous leaf, glandular stipulate, oblong sepals, deeply bucciniform lower sepal, twisted spur with abruptly capitate tip, lanceolate, twisted, obtuse lower later petal, triangular upper lateral petal, linear ovary, oblanceolate—linear fruit.

Habitat and ecology: Impatiens horizontalis horizontally grow and a creeper on gravel stony island frequently flooded along the perennial stream in evergreen forest and is light demander. It hardly survives on other types of soil. 

Distribution: Myanmar. Thus far, limited populations were found on less than 5 gravel islands only along the Nam Phet La stream in Htamanthi Wildlife Sanctuary. 
Vernacular name: “Nam-phet-la Dan-pan”, meaning Dan-pan of Nam-pha-lar stream. 

Note: Impatiens horizontalis is assignable to subgenus Impatiens sect. Racemosae Hook.f. based on its racemose inflorescence, linear capsule and 4 lateral sepals with 2 reduced inner ones. We proposed the local name of the species as “Nam-phet-la Dan-pan” because it was firstly found only along Nam Phet La stream in Htamanthi Wildlife Sanctuary.

Myo Min Latt, Nobuyuki Tanaka and Byung Bae Park. 2023. Two New Species of Impatiens (Balsaminaceae) from Myanmar.  Phytotaxa583(2); 141–152. DOI: 10.11646/phytotaxa.583.2.2