Viola nujiangensis Y.S. Chen & X.H. Jin, 2015

Chen, You-Sheng & Jin, Xiao-Hua, 2015, Viola nujiangensis (Violaceae), a new species of from northwestern Yunnan, China, Phytotaxa 230 (2), pp. 193-197 : 193-196

Viola nujiangensis Y.S. Chen & X.H. Jin , sp. nov. ( Figs. 1–2 )

Type:— CHINA. Yunnan: Gongshan, Cikai, on sandy or rocky slopes of fluctuating zone of Nujiang river , ca. 1450 m, 4 April 2014, X. H. Jin 14120 (holotype PE!; isotype PE!) .

Diagnosis: V. perpusilla Boissieu similis, sed rhizomatibus et radicibus crassore, calcaribus circa 4 mm longis, stipulis et petiolis purpureis, laminis utrinque glaberis differt.

Herbs perennial, acaulescent, 2–5 cm tall. Rhizome stout, erect, branched or unbranched, 1–3 cm long, 1.5–2.5 mm in diameter, often surrounded by remains of leaf petioles of previous year in upper part; root usually stout, grayishwhite, 10–18 cm long, straight descending. Leaves several, all basal; stipules purplish, glabrous, linear-lanceolate, 7–9 mm long, ca. 2/3 adnate to petioles, the free part 3–4 mm long, apex acuminate, margin entire or remotely denticulate; petioles purplish, 1–2.5 cm long, 0.1–0.2 mm wide, narrowly winged in upper part, glabrous; leaf blade ovate to elliptic-ovate, 1–2.5 cm long, 0.4–1 cm wide, both surfaces glabrous, base attenuate, apex obtuse, margin crenuate. Flowers purple-violet, 1–1.5 cm in diameter; pedicels exceeding leaves, slender, 0.1–0.2 mm in diameter, 2- bracteolate above middle; bracteoles subulate-linear, ca. 2 mm long. Sepals triangular, ca. 3 mm long, ca. 1 mm wide, base rounded or truncate, apex acute, margin entire; basal auricles very shorts, 0.1–0.2 mm long. Upper petals obovate, 7–8 mm long, ca. 2.2 mm wide, apex rounded; lateral petals oblong 8–9 mm long, ca. 2.3 mm wide, apex rounded, glabrous; anterior petal ca. 1.2 cm long including spur, ca. 2 mm wide, apex rounded; spur ca. 4 mm long, 1.3–1.6 mm in diameter. Stamens 5, anthers ca. 2 mm long. Ovary ovoid-globose, glabrous; style clavate, base conspicuously geniculate; stigma flat at top, conspicuously margined on lateral sides, shortly breaked in front. Capsule ovoid, 5–6 mm long, glabrous.

Distribution and habitat: — Viola nujiangensis is so far only found in Gongshan, northwestern Yunnan, China, growing on sandy or rocky slopes of fluctuating zone of rivers at altitudes of ca. 1450 m.

Phenology:—Flowering from March to April; fruiting from April to May.

Etymology: —The specific epithet is derived from the type locality name, Nujiang River (=Salween River).

Discussion:— Viola nujiangensis belongs to Viola subgen. Viola sect. Adnatae ( Becker 1925: 368) Wang (1991:

41) because its stipules adnate to petioles and acaulescent habit. It is most similar to V. perpusilla Boissieu (1908: 468) in its acaulescent habit, leaf shape and size, small sepals with very short auricles, but differs by its rhizome and root stout, spur ca. 4 mm long, stipules and petiole purplish, leaf blade glabrous on both surfaces, whereas V. perpusilla is distinct by rhizome and root slender, spur ca. 2 mm long, stipules whitish and membranous, leaf blade adaxially pubescent. Viola nujiangensis is currently known only from Gongshan County, northwestern Yunnan, whereas V. perpusilla occurs in Cangshan Mountain, central Yunnan, growing on grassy slopes at altitudes of 2800–3000 m, flowering from June to October.

To facilitate identification of the 11 species Viola subgen. Viola sect. Adnatae in Yunnan, China, we herewith provide a key to them on the basis of a survey of both literature and herbarium specimens.

Figures

FIGURE 1. Viola nujiangensis, A. Habit; B. Flower (front view); C. Petals; D. Fruit; E. Flower (lateral view); F. Stipules. Drawn based on holytype X.H. Jin 14120 (PE!).

FIGURE 2. Viola nujiangensis. A. Habit; B. Living plants of the type specimens; C. Habitat along Nujiang River.