Lagerstroemia stenophylla B.H.Wu, X.Hu & S.P.Dai, 2023

Wu, Bao-Huan, Hu, Xing, Tu, Wen-Hui, Wang, Wei & Dai, Se-Ping, 2023, Lagerstroemia stenophylla (Lythraceae), a new species from China, PhytoKeys 234, pp. 127-133 : 127

Lagerstroemia stenophylla B.H.Wu, X.Hu & S.P.Dai sp. nov.

Fig. 1

Type.

China. Shannxi: Shangluo, Jinsixia Town , Xinglong Country, in ravine, on rocky slopes. 33°26'36.14"N, 110°32'51.13"E, 387 m a.s.l., 6 June 2023 (fl.), B.H. Wu & W.H. Tu Lg 202334 (Holotype: IBSC!; isotypes: Herbarium of Guangzhou Institute of Forestry and Landscape Architecture!) .

Diagnosis.

Lagerstroemia stenophylla is morphologically similar to L. subcostata Koehne, but distinguished by its branchlets 4-angular, sometimes subalate, leaves elliptic-lanceolate, narrowly elliptic, leaf apex acute, leaf base cuneate, flowers 2.5-3 cm in diameter.

Description.

Shrubs or small trees ca. 0.5-3 m tall. Bark reddish brown, longitudinally fissured and slightly peeling to reveal the inner bark when mature; branchlets scabridulous to glabrous, 4-angular, sometimes subalate. Leaves mostly alternate, or subopposite; petiole 1-3 (4) mm long, densely scabridulous to glabrous; leaf blade herbaceous, margin entire, lanceolate to elliptic-lanceolate, rarely ovate or obovate-oblanceolate, 2-6 (7) × 0.7-2 (2.3) cm, base cuneate, apex acute, sometimes obtuse, rarely apiculate, abaxially pale green, scabridulous (especially along midrib and later veins) to glabrous, adaxially green, sparsely scabridulous to glabrous, lateral veins 4-7 pairs. Inflorescences paniculate, terminal or axillary; panicles (2) 4-7 cm long, densely scabridulous. Flowers sessile or subsessile; flower buds turbinate to subglobose (excluding pseudopedicels). Calyx tubes (excluding pseudopedicels) cup-shaped, 3.3-4.2 mm long, outside densely scabridulous to glabrous, with 10-12 distinctly ribs or dark veins (sometimes not obvious), inside glabrous, with glabrous annulus (sometimes absent) in the throat, lobes 6, sometimes 5, triangular, 1-2.3 mm × 1-2.3 mm, erect, epicalyx absent, pseudopedicel 2-9 mm long; petals 6, crumpled, oblong, suborbicular or ovate, base cuneate to broadly cuneate, rounded, or sometimes subcordate, apex obtuse or rounded, 10-18 mm with claws 3-8 mm long; stamens 20-28, dimorphic, with 6 stamens longer (ca. 15 mm long), thicker and red-brown in color, the remaining stamens are shorter (ca.7 mm long), thinner and white in color, filaments glabrous; ovary glabrous, styles 10-14 mm long, glabrous, stigmas small. Capsules globose to oblong, 6-8 mm long, 4.5-6 mm in diameter, loculicidally dehiscent, 4-7-valved. Seeds ca. 6mm long including wing.

Phenology.

Flowering from May to June, and fruiting after July and fruits persist through winter.

Distribution and habitat.

Lagerstroemia stenophylla is hitherto known from Baihe County, Danfeng County, Shanyang County, Shangnan County, Xunyang County, Zhashui County, Zhen’an County of south-eastern Shaanxi Province and Baokang County, Fang County and Shiyan City of north-western Hubei Province (Fig. 2 ). It grows on rocky slopes in ravine, at 290-770 m elevation.

Etymology.

The epithet of the new species refers to its narrow leaf blade.

Vernacular name.

The Chinese name of the new species is here given as 狭叶紫薇 ( xiá yè zǐ wēi).

Note.

Lagerstroemia stenophylla is formerly misidentified as L. subcostata ( Li and Li 2013). Morphologically, L. stenophylla and L. subcostata share many similar characters, including calyx tubes cup-shaped, with ca. 12 ribs or darkened veins, epicalyx absent, and sepals adaxially glabrous, stamens less than 30, leading to misidentify L. stenophylla as L. subcostata , using the Keys of "Flora Reipublicae Popularis Sinicae" ( Lee and Lau 1983) and "Flora of China" ( Qin and Graham 2007). However, L. stenophylla is a shrub or small tree with conspicuously smaller, narrower leaves and larger flowers, differing distinctly from L. subcostata . Detailed morphological comparisons among L. stenophylla and its relatives are presented in Table 1 .

Additional specimen examined.

China. Shaanxi Province: Baihe County, Maoping, 29 September 1969, Vegetation Team 541 (WUK); ibid., 8 June 2023, B.H. Wu and W.H. Tu Lg202378, Lg202379, Lg202380, Lg202381; Danfeng County, Tumen Town, 6 June 2023, B.H. Wu and W.H. Tu Lg202329, Lg202331; Danfeng County, Zhulinguan Town, Baijiawan, 6 June 2023, B.H. Wu and W.H. Tu Lg202332; Shanyang County, Zhaochuan, 1 July 1960, Huashan Team 0206 (IBSC); Shanyang County, Manchuanguan, 17 September 1952, Z.B. Wang 16543 (KUN, PE, WUK); ibid., 1 May 1964, J.X. Yang 2456 (WUK); ibid., 19 May 2011, S.F. Li et al. 15016 (XBGH); ibid., 5 June 2023, B.H. Wu and W.H. Tu Lg202312, Lg202313, Lg202314, Lg202315, Lg202316, Lg202317, Lg202318, Lg202319; Shangnan County, Jinsixia, 6 June 2023, B.H. Wu and W.H. Tu Lg202335, Lg202336, Lg202337, Lg202338; Xunyang County, on the road from Zhaojiawan to Liangheguan, 7 October 1952, B.Z. Guo 2225 (WUK); Xunyang County, precise locality unknown, 1959, Xida 019 (WUK); Xunyang County, on the road from Zhangping to Xunyang, 19 August 1959, P.Y. Li 8962 (WUK); Xunyang County, Guojiacao, 7 May 2012, S.F. Li et al. 16523 (XBGH); Xunyang County, Liangheguan, 9 June 2023, B.H. Wu and W.H. Tu Lg202384, Lg202385, Lg202386, Lg202387, Lg202388; Zhashui County, Shiweng, 8 June 2008, S.F. Li et al. 10463; Zhen’an County, Lengshuihe, 9 June 2023, B.H. Wu and W.H. Tu Lg202389, Lg202390, Lg202392, Lg202393. Hubei Province: Baokang County, Siping, 21 April 1986, 84Linxue 86-1058 (CCAU); ibid., 8 June 2023, B.H. Wu and W.H. Tu Lg202365, Lg202366, Lg202367, Lg202369, Lg202372; Fang County, Wanyuhe, 8 June 2023, B.H. Wu and W.H. Tu Lg202373, Lg202374, Lg202375; Shiyan City, Wudangshan, 7 June 2023, B.H. Wu and W.H. Tu Lg202343, Lg202344, Lg202345, Lg202346, Lg202347, Lg202348.

Figures

Figure 1. Plate of Lagerstroemia stenophylla A habitat B flowering individuals C stems D flowering branch E fruiting branch F leaves G flower buds H flowers I petals J capsules and seeds.

Figure 2. Distribution of Lagerstroemia stenophylla.