Viola huizhouensis Y. S. Huang & Q. Fan, 2021

Huang, Yan-Shuang, Kang, Ning, Zhong, Xiang-Jing, Liao, Wen-Bo & Fan, Qiang, 2021, A new species of Viola (Violaceae) from Guangdong Province, China, PhytoKeys 176, pp. 67-76 : 67

Viola huizhouensis Y. S. Huang & Q. Fan sp. nov.

Type.

China. Guangdong: Huizhou City, Xiangtoushan National Nature Reserve, Darenyan , 23°15.99'N, 114°22.27'E, 535 m a.s.l., 29 March 2018, Y. S. Huang and Q. Fan 1803 (holotype: SYS; isotypes: IBSC, SYS). (Figs 2 , 3 )

Diagnosis.

Viola huizhouensis is most similar to V. guangzhouensis , but differs by its much stouter rhizome, lack of aerial stem, different leaf shape and dense pubescence of the basal pedicel and the whole plant.

Description.

Herbs, perennial, basal leaves rosulate, 10-15 cm tall. Rhizome erect or obliquely erect, rather stout, 4-7 mm diam.; stolons with an apical rosette of leaves, usually producing adventitious roots. Leaves alternate; stipules leaf-like, base adnate to the petiole, densely pubescent, lanceolate, 6-8 × 1-1.5 mm, apex acuminate, margins sparsely fimbriate or fimbriate-laciniate; petioles densely pubescent, 3-5 cm long, narrowly decurrent-alate; blades narrowly ovate to ovate, apex obtuse, 1.5-3 × 1-2 cm, thinly leathery or chartaceous, densely pubescent, abaxially dark purple, 5 to 7 veins on each side of mid-rib, margin coarsely serrate, base cuneate. Flowers 15-18 mm diam.; pedicels slender, 6-10 cm long, pubescent, usually exceeding leaves, with two opposite bracteoles above middle; bracteoles lanceolate, pubescent, 4-8 mm long, margin entire, apex obtuse. Sepals green, pubescent, linear-lanceolate, 2.7-3.7 × 0.5-1 mm, margin entire, apex obtuse, base truncate or rounded. Petals whitish to light purple, with apparent violet lines, anterior one with a yellow to green patch at base; upper petals, oblong to linear-lanceolate, 2.5-3 × 0.5-0.8 mm, glabrous, margin entire, apex obtuse or erose; lateral petals with glandular hairs at the base adaxially, oblong, 4.5-5 × ca. 1.5 mm, margin entire, apex obtuse or erose; anterior petal with a short saccate spur at base, broadly spathulate or flabellate, margin entire to slightly undulate, apex obtuse. Stamens 5, unequal, puberulent, the anther thecae ca. 1 mm long, terminal appendages ca. 0.7 mm long, the posterior appendages (nectar spurs) of two anterior stamens 0.7-1 mm long. Ovary ovoid to ellipsoid, ca. 0.7 mm diam., puberulent; style ca. 1.0 mm long, conspicuous geniculate at base; stigma thickly margined on lateral sides, slightly raised at central part, shortly beaked at the apex. Capsule with brownish lines at maturity, ovoid, 6-8 mm long. Seeds brown, ovoid, 1-1.5 mm long.

Phenology.

Flowering from March to June, fruiting from April to July.

Distribution, ecology and conservation status.

Populations of Viola huizhouensis were only discovered in Darenyan, Xiangtoushan National Nature Reserve, Guangdong Province. The species was observed to grow on damp cliffs and rocks in broad-leaved forests at altitudes between 400 and 800 m. Its known localities are well protected and more field investigations are needed to determine its distribution.

Note.

Based on its slightly 2-lobed stigma and stolons topped by rosettes of leaves, Viola huizhouensis should be a member of section Viola Diffusae (W. Beck.) C.J. Wang, which was formerly treated as subsection Viola Diffusae under section Viola Viola by Becker (1925). The closest relative of V. huizhouensis on morphological grounds could be V. guangzhouensis . They shared several characteristics, for example, the well-developed rhizome and the bearded lateral petals. The new species can be distinguished from V. guangzhouensis , however, by its much stouter rhizome; lack of aerial stem; different leaf shape (apex obtuse, never acute vs. apex acute); and dense pubescence of the basal pedicel and the whole plant (vs. the basal pedicel sparsely puberulous or subglabrous and the stem glabrous) (Tables 1 , 2 ; Fig. 2 ).

The ITS tree shows that V. huizhouensis is sister to V. guangzhouensis (BS = 100%), then they form a well-supported clade with V. yunnanensis , V. diffusa , V. nanlingensis and V. lucens (BS = 99%) (Fig. 1 ). Viola guangzhouensis and the other four species in this clade all belong to section Viola Diffusae ( Dong et al. 2009). Thus, the phylogenetic analysis supports V. huizhouensis as being close to V. guangzhouensis and belongs to section Viola Diffusae .

In conclusion, the morphological differences and the molecular phylogenetic results provide sufficient evidence for treating V. huizhouensis as a distinct new species and it is a member of section Viola Diffusae (W. Beck.) C.J. Wang ( Wang 1991).

Figures

Figure 1. Maximum Likelihood tree of the new species and related species, Numbers beside branch nodes are bootstraps. Outgroups: Rinorea bengalensis. Viola huizhouensis clade is marked in green and V. guangzhouensis clade is marked in red.

Figure 2. Viola huizhouensis A habitat B habit C young capsule with sepals and bracteoles D stem with stipules E abaxial surface of leaf blade F bracteoles G flowers H petals I longitudinal section of stigma and ovary J comparison of leaf blades. Left, V. guangzhouensis. Right, V. huizhouensis. K. Specimen of V. huizhouensis (Y. S. Huang and Q. Fan 1803). L. Specimen of V. guangzhouensis (Y. S. Huang 1804).

Figure 3. Viola huizhouensis A habit and flowering branch B leaf and stipules C flower, front view and lateral view D young capsule with sepals and bracteoles and dehiscent capsule with seeds E stamens in adaxial view (below) and abaxial view (above) F stigma and pistil G bracteoles H petals.