Impatiens lhunzeensis J.Tian, G.W.Hu & Q.F.Wang

Tian, Jing, Yuan, Tao-Hua, Peng, Shuai, Yang, Zhu-Zhu, Hu, Guang-Wan & Wang, Qing- Feng, 2024, A new species of Impatiens (Balsaminaceae) from Southern Xizang, China with supplementary knowledge on I. leptocarpa Hook. f., Phytotaxa 661 (1), pp. 47-62 : 52

1. Impatiens lhunzeensis J.Tian, G.W.Hu & Q.F.Wang , sp. nov. ( Figs. 1 & 2 , Fig. 3 : A1–I1)

Type: — CHINA. Xizang: Shannan Prefecture, Lhunze County, Zhari Township , evergreen broad-leaved forests along understory streams, 2671 m, 28°35′58″N, 93°24′14″E, 14 July 2022, J. Tian & C. Zhang TIBET-TJ3 (holotype: HIB, HIB0209753 ; isotypes: HIB, HIB0209754 , HIB0209755 , HIB0209756 ) .

Diagnosis: — Impatiens lhunzeensis is different from I. radiata Hook.f. , I. harae H.Ohba & S.Akiyama , I. drepanophora Hook.f. (1905: 22) , I. principis Hook.f. (1908: 246) , and I. eubotrya Miq. (1860: 397) by a combination of following characters: indumentum present on the stem, leaf blade densely hairy, racemose inflorescence, peduncle hairy in lower parts, reniform dorsal petal, navicular lower sepal, broadly ovate to sub-orbicular upper petals, and triangular oblong lower petals.

Description: —Annual, non-succulent herbs, 24–50 cm high; stems erect, robust, branched, densely hairy. Leaves alternate; petiole 0.5–2.5 cm long, densely hairy, with 2 clavate basal glands; leaf blade ovate, 1–8 × 0.8–3.5 cm, densely hairy above and on veins beneath, lateral veins 5–9 pairs, margin crenate, apex acuminate. Inflorescence in upper leaf axils, racemose, 6–26-flowered; peduncle 5–10 (to 15) cm long, lower parts hairy, upper parts glabrous; pedicel 1.4–1.9 cm long; bracts ovate, 0.2–0.3 cm long, persistent, apex glandular slender. Flowers pale-pinkish to white, 1.8–2.1 cm long, small; lateral sepals 2, ovate-lanceolate, 0.2–0.3 cm long, apex long mucronulate; lower sepal navicular, apex rostellate, ca. 0.5× 1.2 cm, gradually tapering into straight 0.6–0.8 cm long spur; dorsal petal reniform, apex rounded, ca. 0.3 × 0.5 cm; lateral united petals white to pink, 1.6–1.8 cm, 2-lobed; upper petal broadly ovate to sub-orbicular, 0.2–0.3 × 0.2–0.3 cm, lower petal triangular oblong, 1.0–1.2 × 0.5 cm, apex obtuse. Anthers obtuse. Ovary 5-carpellate. Capsule linear, 1.8–2.2 cm. Seeds unknown.

Etymology: —The specific epithet “ lhunzeensis ” refers to the type locality, Lhunze County. The Chinese name is given as “̎子凤仙花” (lóng-zǐ-fèng-xiān-huā).

Phenology: —Flowering late July to August, fruiting late August to September.

Habitats: —Moist roadside ditches on the forest margins in the mountains at an elevation range from 2500 to 2800 m.

Distribution: — Impatiens lhunzeensis is only found in Lhunze, Xizang, China.

Phylogenetic position:— Phylogenetic analysis shows that the new species is nested within I. sect. Racemosae , along with three closely related species: I. principis , I. eubotrya , and I. drepanophora . The clade consisting of the new species and its close relatives is strongly supported by both maximum likelihood and Bayesian inference phylogenetic trees ( Fig. 4 ).

Figures

FIGURE 1. Impatiens lhunzeensis. A. habit; B. glands at the petiole base; C. lateral view of flower; D. front view of flower; E. dissection of a flower (a. dorsal petal; b. lateral sepals; c. lateral united petals; d. lower sepal; e. stamens and pedicel); F. capsule. Drawn by Jing Tian, based on the holotype.

FIGURE 2. Impatiens lhunzeensis. A. habitat; B. flowering branch; C. branches, bottom view; D. root and basal part of stem, showing node; E. inflorescence; F. adaxial and abaxial view of leaf; G. front, bottom and lateral view of flower; H. dissection of a flower (a. dorsal petal; b. lateral sepals; c. lateral united petals; d. lower sepal; e. stamens and pedicel); I. capsule. Photographed by Jing Tian.

FIGURE 3. Impatiens lhunzeensis (A1–I1), I. radiata (A2–I2), and I. harae (A3–I3).A. habit; B. glands; C. inflorescences; D. front view of flowers; E. lateral view of flowers; F. dorsal petals; G. lateral sepals; H. lateral united petals; I. lower sepals. Impatiens lhunzeensis and I. radiata: photographed by Jing Tian, I. harae: photographed by Jia-Xin Yang.

FIGURE 4. The phylogenetic tree based on a combined dataset of nrITS and plastid atpB-rbcL DNA sequences.The bootstrap percentages (BP) for maximum likelihood (ML) and posterior probabilities (PP) of Bayesian inference (BI) are shown in the branch (BP/PP, the dash [-] indicates BP<80 or PP<0.80 at a node, and the asterisk [*] indicates BP=100 or PP=1.00). Only the ML tree is shown, because its topology is nearly identical to the BI tree. Impatiens lhunzeensis and I. leptocarpa are highlighted in red.