Impatiens guiqingensis S. X. Yu, 2016

Guo, Hui, Zhang, Cai-Fei, Zhang, Lin-Jing & Yu, Sheng-Xiang, 2016, Impatiens guiqingensis (Balsaminaceae), a new species from Gansu, China, Phytotaxa 247 (3), pp. 229-233 : 229-232

Impatiens guiqingensis S. X. Yu , sp. nov. ( Figs.1 , 2 )

The new species is similar to I. dicentra superficially in having 1–2 flowered racemose inflorescences, lateral sepals with dentate margin, top of lower and upper petals of lateral united petals with bristle appendages, but differs from the latter by yellow flower, lower sepal without spur and dorsal petal with unapparent crest.

Type: CHINA, Gansu Province, Zhangxian County, Guiqingshan, Shady places in forest, alt. 2440 m above sea level, 34°37’46” N, 104°28’08” E, 11. September 2008, Cai-Fei Zhang 1274 (holotype PE, isotype IBK).

Annual herb, 30–50 cm tall. Stems succulent, glabrous, erect, often branched above. Leaves alternate, aggregated towards the top of the stems; petiolate. Petiole 1–2 cm long. Blades 5–8 (–11) cm long, 3–5 cm wide, lanceolate; lateral veins 7–9 pairs; margin crenate-serrate, with simple narrow teeth; apex acute, base crenate. Racemes in upper axils, 1 (–2) flowered with peduncle ca. 1 mm long. Bracts ca. 2 mm long, ovate-lanceolate, inconspicuous. Pedicels 1 cm long, slender, glabrous. Flowers yellow. Lateral sepals 2, the outer pair 1–1.2 cm long, 0.5–1 cm wide, ovateorbiculate, conchate, 9-veined, dorsal ridge apparent winged, apex mucronate. Lower sepal ca. 1.5–2 cm long, ca. 1 cm deep, infundibuliform, absent spur. Upper petal ca. 0.2–1 cm long, ca. 0.8 cm wide, elliptic or ovate-elliptic, apex mucronate, dorsally with a narrow crest. Lateral united petals 2–2.5 cm long, upper petal of each pair 1–1.5 cm long and ca. 0.5 wide, shortly stalked, lanceolate, with midvein ending in a conspicuous bristle appendage; lower petal of each pair ca. 1.5 cm long, ca. 1 cm wide, obovate-oblong, with midvein ending in a bristle appendage. Stamens 5; filaments 5–6 mm long, flat; anthers obtuse. Ovary glabrous. Capsule glabrous, ca. 2 cm long.

Phenology:—The new species is flowering in August and fruiting in September.

Distribution and habitat:— Impatiens guiqingensis grows sparsely in small populations, and is only found in the Guiqingshan mountain, Zhangxian County, Gansu province, at ca. 2440 m., while I. dicentra is confined to Central China, such as western Hubei, eastern Chongqing ( Fig. 3).

Etymology:—The specific epithet ‘guiqingensis’ refers to the locality of the type specimen, Guiqingshan mountain, Zhangxian County, Gansu, China.

Conservation status:— Impatiens guiqingensis is known for about 150 individuals covering less than 5 km 2. This species is confined in a national park, so it is not received any special conservation and the outside of its distribution are also disturbed by some tourist. It should be treated as Critically Endangered (CR) based on the International Union for Conservation of Nature Red List Categories and Criteria B2a.

Discussion

After detailed studies, we found that Impatiens guiqingensis is close to I. dicentra superficially. However, the former can be easily distinguished by: blades lanceolate or elliptic-lanceolate, 1 (–2) flowered racemose inflorescence (vs. 2-flowered racemose inflorescence), dorsal ridge of lateral sepal winged (vs. dorsal ridge of lateral sepal unapparent), lower sepal without spur (vs. lower sepal with bifid spur) and dorsal petal with unapparent crest (vs. dorsal petal with apparent winged crest). The distributions of the two species are also isolated from each other. For the new species, Impatiens guiqingensis , is confined to southeastern of Guasu province, whereas the related species is recorded in western Hubei, eastern Chongqing and northern Hunan province. The occurrences of these two species are not overlaped with each other ( Fig. 3)

In order to illustrate the morphology circumscription of the new species, further four species with similar morphological characters, I. guiqingensis , I. dicentra , I. davidii Franch. (1886: 65) and I. noli-tangera Linnaeus (1753: 983) are compared with each other, on the basis of their reproductive and vegetative characters in Table 1.

tangera.

Figures

FIGURE 1. Impatiens guiqingensis; A. habit; B. flower (lateral view); C. flower (front view); D. lower sepal; E. lateral united petals; E1. upper petal; E2. lower petal; F. dorsal petal; G. outer lateral sepal; H. androecium. (Drawn by P. Liu from C. F. Zhang 1274).

FIGURE 2. Impatiens guiqingensis. A–B. flower branches. C. flower in front view. D. flower in lateral view (photographed by C. F. Zhang).