Viola evoluta C. Z. Huang, X. Zhong and Xiao C. Li sp. nov.

Viola evoluta C. Z. Huang, X. Zhong and Xiao C. Li sp. nov.

> Viola subsect. Viola

Diagnosis 

A species most similar to V. hondoensis W. Becker and H. Boissieu (see table 1), but distinguished by its cordate (versus broadly ovate to reniform) and nearly glabrous leaf blade (versus conspicuously spreading white-pubescent), with glandular crenate-serrated (versus crenate) and cuspidate apex (versus apex rounded)(see Fig. 3), white flowers, and lanceolate sepals with acute apex (versus narrowly oblong or ovate with obtuse apices)

Type 

China, Hunan Province (湖南省), Zhuzhou City ( 株洲市), Yanling County (炎陵县), Zhongcun Yao Ethnic Township (中村瑶族乡), Xinshan Village (鑫山村), Zhushanxia Production Team (竹山下组), Pingbanqiao (平 板桥). 26°6ʹ55.80ʺ’N, 113°50ʹ10.68ʺE, 939 m a.s.l., Huang Cun-zhong, 5 Mar. 2024, in flower, HCZ20240305-1 (Holotype: CSH0202743 CSH; Isotypes: CSFI, KUN, IBSC, HZU); same locality, Huang Cun-zhong, 2 May 2024, in fruit, HCZ20240502-1 (Paratypes: CSH, CSFI, KUN, IBSC, HZU). 

Etymology

The specific epithet ‘evoluta’ was derived from Latin meaning unrolling, unfolding, or opening, and is chosen to describe the conspicuously developed stolons. A chinese name was given as ‘罗霄堇菜 (luó xiāo jǐn cài)’, which refers to the Luoxiaoshan range where the type locality is situated.

Description (Fig. 1-4 and photos from CHF)

Herb perennial, usually not more than 8 cm heigh; rhizome slender, erect or oblique, sometimes covered by persistent stipules; nodes densely spaced, producing one or more taproot and several fibrils; internodes elongated in fruit. Aerial stem absent. Stolons well-developed, conspicuously creeping, up to ca 50 cm long, glabrous, producing roots from nodes. Stipules free, lanceolate, 1.0–1.5 cm long, with sparsely fimbriate margin, radical ones narrower. Petioles of unequal length, up to 15 cm in fruit. Leaf blades cordate, broadly cordate with deep sinus at base, cuspidate at apex, 2.5–6.5 × 3–7 cm, sparsely pubescent or glabrous, green adaxially, green-whitish abaxially, with glandular-crenate to serrate margin; stem leaves smaller; leaves in summer larger than those in spring. Pedicels equaling or slightly exceeding leaves, slender, 2.0–6.5 cm, longer in fruit. Bracts 2, above the middle of pedicels, nearly opposite, linearlanceolate, 3–5mm, entire or slightly fimbriate along margin. Sepals 5, lanceolate, glabrous, 3-veined, acute at apex, with narrowly membranous margin, outer 3 ones wider; basal appendage 1–2 mm, rounded or irregularly dentate at apex. Flower white, 1.0–1.5 cm in diameter; petals 5, upper two narrowly ovate, lateral ones broadly ovate, directed forwards, slightly bearded or glabrous at the base, anterior one larger, rounded at base, lilac-striate, 1.2–1.5 cm long (including spur); spur cylindrical, 3–6 mm, usually red-tinged, abruptly upward-curved at apex. Ovary slightly hairy; style base slightly geniculate, gradually thickened upward, at apex narrowed to ca 1.5 mm hooked beak. Stamens 5, ca 2.5 mm, the lowermost two each with a nectariferous appendage projecting into the spur, oblong, rounded at apex. Capsules globose, pubescent, ca 5 mm in diameter, inexplosive, lying on the ground. Seeds globose or ellipsoidal, covered with irregular bumps when mature, yellow 

Phenology

Chasmogamous flowers were observed from March to April; cleistogamous flowers were observed in April. Fruits were observed from May to July in 2024.

Distribution and ecology

Viola evoluta was found in mixed forests at an elevation ranging from 761 m to 1300 m a.s.l., typically in ravines or by a stream. Three populations with specimen records are known

in Luoxiaoshan range (Fig. 4 and 5), situated between Hunan and Jiangxi Province

Conservation status 

Based on field work and specimen examination, at least three stable populations of V. evoluta have been identified in Luoxiaoshan range, and individuals in these populations were observed to produce seeds naturally. Considering the north-south orientation of the mountain range, it is anticipated that additional populations may be discovered on both the northern and southern sides (Fig. 5). A population of this new species was also found in Tianmenshan, Zhangjiajie City, Hunan according to the authors' personal communication and the record of Plant Photo Bank of China (https:// ppbc.iplant.cn/tu/1759286). Currently, there is no immediate threats to these populations, so this new species is currently classified as ‘Least Concern’ (LC). 

References

Zhong, Xin et al. “Viola evoluta sp. nov. (Violaceae) from central southern China.” Nordic Journal of Botany (2024): 12 December 2024. pag. 1-10; https://dx.doi.org/10.1111/njb.04610 

Wang, D. Q., Qing, Z., Xie, J., Cheng, M. E. and Zhang, L. 2019. Four new species of flowering plants from Anhui. – J. West Anhui Univ. 35: 67–68. (in Chinese).