Impatiens casseabriae Y.H.Tan, S.S. Zhou & B.Yang, 2017

Yang, Bin, Zhou, Shi-Shun, Maung, Kyaw Win & Tan, Yun-Hong, 2017, Two new species of Impatiens (Balsaminaceae) from Putao, Kachin State, northern Myanmar, Phytotaxa 321 (1), pp. 103-113 : 104-107

1. Impatiens casseabriae Y.H.Tan, S.S. Zhou & B.Yang , sp. nov. ( Figs. 1 , 2 : A–F)

Diagnosis:—The new species is similar to Impatiems margaritifera Hooker (1908: 249) in flowers characters and I. taronensis Handel-Mazzetti (1933: 652) in leaf shape, but it can be easily distinguished from the former by its narrowly elliptic to narrowly oblanceolate leaves, petioles up to 3 mm long and 25–40 mm long lower lateral united petals, and from the later by its white flowers without spur.

Type: — MYANMAR. Kachin State: Putao, Hkakabo-razi National Park , 97º51 ʹ 9 ʺ E, 27º43 ʹ 28 ʺ N, alt. 1200 m, 28 Nov. 2014, Myanmar Exped. 248 (holotype: HITBC!; isotypes: KUN!, RAF!) .

Herb perennial, 15–30 cm tall, glabrous. Stem erect to decumbent in the lower part, green or kermesinus-tinged in upper part, simple or branched; inferior nodes swollen, inconspicuous when dry. Leaves spirally arranged, aggregated at stem apex, sub-sessile or shortly petiolate; petiole up to 5 mm long; blade 2.5–7 × 0.4–1.2 cm, narrowly elliptic to narrowly oblanceolate, apex acute to acuminate, base cuneate, adaxially green with kermesinus margin, abaxially pale green, sometimes kermesinus nearly base, margin deeply crenate, with spinose teeth, lateral veins 8–12 pairs. Racemes solitary in the upper axils, erect, 1.5–5.0 cm long, 1–3-flowered. Pedicels thin, 8–17 mm long. Bracts elliptic or ovate-lanceolate, ca. 5 × 1.5 mm, apex acuminate and mucronate, base obtuse, margin entire, persistent. Flowers white. Lateral sepals 4, the outer 2 larger, obliquely ovate, ca. 3 × 1.5 mm, free, apex acuminate to mucronate, base obtuse, the inner 2 small, ovate, ca.1.5 × 1 mm, apex acute, base obtuse; lower sepal 7–9 × 3–4 mm, navicular or obovate-elliptic, apex acuminate and mucronate, spurless. Dorsal petal 5.5–7.5 × 5.0–6.0 mm, obovate to orbicular, apex emarginate, base cuneate, midrib obvious, with a slight dorsal crest; lateral united petals 2.7–4.2 cm long; the upper petal obliquely ovate-triangular, 8–9 × 2.5–3.5 mm, apex acute, base cuneate; the lower petals 2.5–4.0 × 0.8–1.0 cm, narrowly dolabriform or oblong-dolabriform, apex acute, with a long narrow appendage, base with yellow patch. Stamens 5; filaments linear, ca. 2.5 mm long; anthers white, obtuse. Ovary ca. 2–2.5 mm long, ca. 1 mm in diam., glabrous,green. Capsule 1.5 cm long, ca. 1.5 mm in diam., linear, glabrous, green.

Phenology: —Flowering and fruiting from October to the following May.

Distribution and habitat: — Impatiens casseabriae is known from Putao, Kachin State, Myanmar. It grows on wet rock or cliff along the waterfall in tropical montane forests, 1000–1200 m.

Etymology:— The specific epithet is derived from the abbreviation of Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences (CAS-SEABRI); noun in apposiation. The name is dedicated to its three-part mission, viz., (a) Serve China’s “the Silk Road Economic Belt and the 21 st Century Maritime Silk Road” initiative; (b) Integrate efforts by CAS and international institutes to organize professional research groups and train researchers in Southeast Asian countries; and (c) Provide support to all domestic and international partners.

Affinities:— This species is similar to Impatiens margaritifera , particularly in the absence of spur and small white flowers, but differs in its narrowly elliptic to narrowly oblanceolate leaves, petioles up to 3 mm long, 25–40 mm long lower lateral united petals, distal longer swallow-tailed ( Table 1, Figs. 1 , 2 : A–F). The new species is also similar to I. taronensis in leaf characters, but differs in the white (not purple) flowers without spur (not with erect or slightly curved spur).

Figures

FIGURE 1. Impatiens casseabriae. A, B. Habit; C. Dorsal petal; D. Outer lateral sepal, abaxial surface and adaxial surface; E. Inner lateral sepal; F. United lateral petals; G. Lower sepal, adaxially view; H. Pedicel with androecium and gynoecium; I. pedicel with immature capsule. Drawn by Zheng-mengYang from Myanmar Exped. 248 (HITBC).

FIGURE 2. Impatiens casseabriae. A-D. Habit; E. Different parts of the flower and capsule; F. Flower (front view). Impatiens putaoensis. G, H. Habit; I. Different parts of the flower, pedicel with immature capsule and pedicel with flower (lateral view).