Viola austroyunnanensis Y.S. Chen, 2023

Liao, Shu-Yuan, Liao, Jun-Jie, He, De-Ming, Wu, Jian-Yong & Chen, You-Sheng, 2023, Viola austroyunanensis (Violaceae), a new species from Yunnan province of China, Phytotaxa 613 (2), pp. 153-161 : 154-158

Viola austroyunnanensis Y.S. Chen , sp. nov. ( Figure 1–3 ).

Type: CHINA, Yunnan, Wenshan county, Zhuilijie town , Yahuzhai , 103°22′16.57”E, 23°17′16.37”N, 1580 m, 24 Apr. 2020, You-Sheng Chen et al. WS1214 (holotype IBSC; isotypes IBSC, PE) .

Herbs perennial. Rhizome robust, to 7 cm long. Stolons elongated, glabrous, usually with scattered leaves and rosette new plants. Leaves nearly basal or alternate on aerial stolons; stipules mostly free, green, lanceolate, ca. 1 cm long, ca. 2 mm wide, margin long fimbriate-dentate, apex acuminate, base adnate to petioles; petioles 1.5–6.5 cm long, glabrous, wingless; leaf blade ovate-cordate, 2–5.5 cm long, 2–3.7 cm wide, adaxially glandular pubescent, abaxially glabrous, base cordate, margin obtusely dentate, apex acute. Flowers blue-purple to white; pedicels usually exceeding leaves in flowering period, glabrous, 2-bracteolate above middle; bracteoles opposite, linear. Sepals oblong, glabrous, ca. 5 mm long and ca. 1 mm wide, apex acute, basal auricles short, 0.5–1 mm long, 3-veined, margin glabrous outside, apex truncate. Petals oblong-obovate, 10–11 mm long, apex obtuse, lateral ones glabrous, anterior one ca. 9–11 mm long (spur included), apex acute; spur saccate, short, 2–3 mm long, stout, 2.2 mm in diam.; spur of 2 anterior stamens angular, slightly longer than anthers, apex acute. Ovary conic, glabrous; styles clavate, base slightly geniculate, thickened upward, slightly flat at apex, conspicuously margined on lateral sides, shortly beaked in front, with a stigma hole open upward at tip of beak. Capsule ellipsoid, ca. 7 mm long, glabrous.

Distribution and habitat: Viola austroyunnanensis is found from Wenshan county and Yuanyang county, southeastern Yunnan province, China. It was observed to grow in sparse evergreen forests or karst rocky thickets at elevations from 1500 to 2000 m.

Phenology: Flowering from March to April, fruiting from April to October.

Etymology: The epithet “ austroyunnanensis ” refers to the distribution range of the new species, southern Yunnan province.

Additional specimens examined (paratypes): China, Yunnan, Wenshan county, Zhuilijie town, Yahuzhai , 1577 m, 18 Oct. 2019, You-Sheng Chen et al. WS0422 ( IBSC); Yuanyang county , Huangmaoling town , Dashan , 1930 m, 20 Oct. 2019, You-Sheng Chen et al. YY0426 ( IBSC); Yuanyang county , Daping town , Huizhulin , 2000 m, 2 Apr. 2020, You-Sheng Chen et al. YY1233 ( IBSC); Yuanyang county , Huangcaoling town , Dapai , 1500 m, 4 Apr. 2020, You-Sheng Chen et al. YY1310 ( IBSC) .

Discussion: Viola austroyunnanensis belongs to V. sect. Diffusae ( Becker 1923: 113) Wang (1991: 100) based on the plant with aerial stolons, stipules mostly free, base adnate to petioles, and margins long fimbriate-dentate, styles clavate, and base slightly geniculate, conspicuously margined on lateral sides. Phylogenetically, V. austroyunnanensis is resolved as a member of V. sect. Adnatae . Therefore, the systematic position of V. austroyunnanensis needs further research.

Viola austroyunnanensis is most similar to V. fargesii Boissieu (1902: 333) in its habit (perennial herbs has slender, elongated stolons with scattered leaves), leaf cordate, aerial stolons and lower petals with short spur, but differs from the latter by its stolons, petioles, stipules, abaxial leaf surface and sepals all glabrous (vs. white puberulous), later petals glabrous (vs. beard), flower color usually blue-purple (vs. white); corolla throat nearly white (vs. yellow). The ML tree shows the V. fargesii as a single sister clade with V.sect. Bilobatae (Becker 1917: 226) Juzepczuk (1949: 439), V. sect. Diffusae and V. sect. Adnatae .

Figures

FIGURE 1. ML tree of the new putative new species and related species inferred by IQ-Tree based on ITS dataset. Bootstrap values of the Maximum Likelihood are shown along the branches. Outgroup taxa: Rinorea bengalensis and Hybanthus enneaspermus.

FIGURE 2. Line illustration of Viola austroyunnanensis sp. nov. A. habit; B. young fruit with petals in lateral view; C. young fruit with petals in front view; D. flower in front view; E. lower petal; F. upper petal; G. lateral petal; H. stipules. Scale bars: A= 2 cm; D=1 cm; B, C, E, F, G, H =1 cm.

FIGURE 3. Viola austroyunnanensis sp. nov. in the wild. A. habit; B. living plant. (photos taken by Jun-Jie Liao from You-Sheng Chen et al. WS1214)