Lagerstroemia densa C. H. Gu & D. D. Ma, 2015

Gu, Cui Hua, Ma, Dan Dan, Tembrock, Xu Dan Zhu Luke R. & Wang, Xian, 2015, Lagerstroemia densa (Lythraceae), a new species from Daqing Mountain, Guangxi Zhuang Autonomic Region, China, Phytotaxa 204 (3), pp. 230-234 : 230-233

Lagerstroemia densa C. H. Gu & D. D. Ma , sp. nov.

Type:— CHINA. Guangxi: Daqing Mountain, in dense forest, 22°19 ′ 27 ″ N, 106°59 ′ 30 ″ E, 635 m elev., 14 July 2013, C. H. Gu & D.D. Ma (holotype ZJFC 1307141!, isotypes ZMNH!, HBGH!). Figures 1 , 2 .

Species nova Lagerstroemiae subcostatae Koehne similis , sed calyce non costato, pubescente, capsula omnino globosa differt; etiam similis L. excelsae , sed folio anguste elliptico vel lanceolato, petalo basi obliquo, ovato differt.

Tree ca 2–3 m tall. Bark peeling, reddish-brown, smooth; branchlets pubescent, terete. Leaves mostly opposite; petiole 2–3 mm; leaf blade membranous, narrowly elliptic lanceolate, 2–9 × 1–5 cm, base broadly cuneate, apex acuminate, adaxially densely pubescent, abaxially pilose, along midrib densely stellate pubescent, lateral veins 4–11 pairs. Panicles 8–10 cm, densely gray pubescent, densely flowered. Flowers small, densely grouped, white or pale pink, diameter 6–8 mm. Floral tube length 3 mm, densely white pilose, without ribs, suture lines red, lobes 4–7, triangular, erect; sepals pubescent, epicalyx absent; petals 6, 2–3 mm long including claw, 1 mm wide, edge of petals crinkled, the petal shape base oblique and ovate. Stamens 14–30, dimorphic, 6 stamens 4 mm long, stamens 8 to 24, 2 mm long, filaments slender. Ovary glabrous, 5–locular. Capsule globose, 2–3 mm in diameter, loculicidally dehiscent, 4–6-valved. Seeds 2 mm long including wing, unilaterally winged from raphe, dark brown.

Distribution, habitat and phenology:—So far only one population is known from Daqing Mountain, Chongzuo City, Guangxi Zhuang Autonomic Region, China, where it grows in a secondary monsoon evergreen broad leaf forest, at 700–900 m elevation. The overstory of the forest was dominated by Beilschmiedia percoriacea C.K.Allen (1942: 450) , Macaranga denticulata (Blume) Müller Argoviensis (Blume 1826: 625; Müller 1866: 1000), Quercus griffithii Hooker filius & Thomson ex Miquel (1864: 104) and Cyclobalanopsis glauca Oersted (1866: 78) , with scattered wild populations of Lagerstroemia indica Linnaeus (1759: 1076) . The understory shrub and herb species mainly included Euodia lepta (Sprengel) Merrill (Sprengel 1825: 496; Merrill 1935: 215), Ilex rotunda Thunberg (1784: 168) , Schefflera octophylla Harms (1894: 38) , Alpinia japonica Miquel (1867: 140) , Miscanthus floridulus (Labillardière) Warburg ex K.Schumann & Lauterbach (Labillardière 1824: 18; Schumann & Lauterbach 1901: 166) and Adiantum capillus-veneris Linnaeus (1753: 1096) . In spite of striving to find other populations of this species in the area, it was not found at lower (500–700 m) or higher (900–1100 m) elevations. Flowers were collected from June to August, and fruits from July to October.

Affinities:— Lagerstroemia densa is similar to L. subcostata Koehne (1883: 20) , from which it is distinguished through the characters given in the diagnosis and Table 1. It is also similar to L. excelsa (Dode) Chun ex S.K.Lee & L.F.Lau (Dode 1909: 232; Lee & Lau 1983: 104) in the shape of the floral tube lobes and inflorescences, and is also compared with it in Table 1. Due to the presence of dendritic trichomes, L. densa may be confused with L. balansae Koehne (1897: 35) and L. tomentosa C.Presl (1844: 572) , but it differs from these species by its white pubescence (versus golden to red-brown in the other two species).

Etymology:—the name of this species was chosen due the dense pubescence occurring throughout the plant.

Figures

FIGURE 1.A–J. Lagerstroemia densa (from the holotype). A. Flowering branch and inflorescence. B. Branchlet. C. Single inflorescence. D. Fruiting branch. E.A single flower. F.A single flower. G. Flower with petals removed. H. Cross section of ovary. I. Longitudinal section of ovary with style. J. Fruit (Illustrations X. D. Zhu).

FIGURE 2. A. Bark of L. densa. B–C. Inflorescences of L. densa. D. Flowers of L. densa. (Photos C.H. Gu).