Impatiens ngariensis S. Peng, G. W. Hu & Q. F. Wang 2026, sp. nov.

Impatiens ngariensis S. Peng, G. W. Hu & Q. F. Wang sp. nov. Fig. 1, Fig. 2: A 1 – H 1 Type. China • Xizang: Ngari Prefecture, Zanda County, Diyag Township, Sibgyi Village, understorey streamside wetlands, 3086 m alt., 31°48'36"N, 78°44'48"E, 15 Aug 2023, S. Peng, T. H. Yuan, M. Liao & C. Q. Shen PS- 00499 (holotype: HIB [HIB 0258833]; isotypes: HIB [HIB 0258834 and HIB 0258835]). Diagnosis. Impatiens ngariensis is morphologically allied to I. thomsonii and I. sulcata, but differs from the former by its larger flowers, suborbicular (vs. orbicular) dorsal petal and a markedly shorter spur (4–6 mm vs. 1 cm); from the latter, it is distinguished by the oblong (vs. broadly dolabriform to broadly elliptic or ovate) upper petal, dolabriform (vs. subdolabriform to oblong-ovate) lower petal and a broadly funnel-form (vs. saccate) lower sepal. Description. Annual herbs, 30.5–66.0 cm tall. Stem purplish-red or green, erect, succulent, simple or sparsely branched, glabrous. Leaves alternate; petiole 0.5–2.0 cm, with a pair of deep purplish-red globose or stipitate glands at base; leaf blade elliptic-ovate or oblong-lanceolate, 6.4–12.3 cm × 3.1–3.8 cm, apex acuminate or long acuminate, base cuneate or subrounded, with a pair of stipitate glands, margin crenate-serrate, setose between teeth, lateral veins 6–7 pairs. Inflorescences in upper leaf axils, subcorymbose-racemose, 2–5 - flowered; peduncle 2.4–5.5 cm long, pedicel 1.8–2.1 cm long, swollen at apex, bracteate at base; bracts ovate, 0.6–0.7 cm, apex cuspidate, purplish-red or yellowish-green. Flowers white to pale pink, 3.6–4.8 cm long; lateral sepals 2, inequilateral, broadly ovate, 0.6–0.7 cm long, apex apiculate; Lower sepal broadly funnel-form, 1.2–1.6 cm deep, gradually tapering into an incurved, short spur, 0.4–0.6 cm, mouth oblique, 2.8–3.5 cm wide, tip acuminate; dorsal petal suborbicular, ca. 1.9–2.8 cm × 1.8 cm, base cordate, apex emarginate, mucronulate, abaxial mid-vein with a narrow keel; lateral united petals sessile, ca. 2.3–3.0 cm, upper petals oblong, ca. 1.9 cm × 0.9 cm, apex obtuse, lower petals dolabriform, ca. 1.2 cm × 0.8 cm, apex acute, auricle inflexed. Anthers obtuse. Ovary 5 - carpellate. Capsules linear, 1.3–2.0 cm, apex rostrum pointed. Seeds ellipsoid, tuberculate. Etymology. The specific epithet “ ngari ” refers to the type locality, Ngari Prefecture. The Chinese name is given as “ 阿里凤仙花 ” (ā-lĬ-fèng-xiān-huā). Phenology. Flowering late July to August, fruiting August to September. Habitats. Understorey streamside wetlands at about 3090 m elevation. Distribution. Impatiens ngariensis is only found in Zanda, Xizang, China (Fig. 3). Conservation status. The new species is currently known from a single population within China, close to the national border. Due to the lack of comprehensive surveys outside China and insufficient information on its global distribution and population size, it is assessed as Data Deficient (DD), based on International Union for Conservation of Nature (IUCN) Red List Categories and Criteria (IUCN 2025). Phylogenetic position. Phylogenetic analysis indicates that the new species is nested within I. sect. Racemosae and is most closely related to I. thomsonii, forming a sister group with it. In addition, they constitute a strongly supported monophyletic clade with six related species: I. glandulifera, I. edgeworthii, I. fragicolor, I. sulcata, I. bomiensis and I. chungtienensis. 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). Additional specimens examined (paratype). China. • Xizang: Ngari Prefecture, Zanda County, Diyag Township, Sibgyi Village, understorey streamside wetlands, 3086 m alt., 31°48'36"N, 78°44'48"E, 15 Aug 2023, S. Peng, T. H. Yuan, M. Liao & C. Q. Shen AL- 0459 (HIB); 15 Jul 2024, J. Tian, T. Hu, J. Z. Su & R. P. Li AL- 2383 (HIB).