Quercus pseudosetulosa Q.S. Li & T.Y. Tu, 2018

Li, Qiansheng, Li, Shengchun, Lin, Duoqing, Shao, Wen & Tu, Tieyao, 2018, Quercus pseudosetulosa, a new species of Quercus sect. Ilex (Fagaceae) from Dawanshan Island, Guangdong, China, Phytotaxa 373 (4), pp. 272-282 : 273-276

Quercus pseudosetulosa Q.S. Li & T.Y. Tu , sp. nov. ( Fig.1 )

Similar to Q. setulosa and Q. bawanglingensis C.C. Huang, Z.X. Li & F.W. Xing in Huang & Chang (1990: 10) by the leaf with sharp spinose teeth and shining glabrous with prominent tertiary vein, but it is different to the latter by the long petiole, abaxially reflexed leaf blade and prominent grayish-yellow lenticels on branches of current year.

TYPE:— CHINA. Guangdong Province: Zhuhai, Dawanshan Island , 113°43’0.6”E, 21°56’58.2”N, 27 m, amongst shrubs on the open rocky slope, T. Y. Tu & S. C. Li 185 (holotype CSH! [Herbarium barcode: CSH0140813 , Fig. 2 ]; isotypes CSH!, IBSC!) .

Additional specimens examined:— CHINA. Guangdong: Zhuhai, Dawanshan Island , 113°43’0.96”E, 21°56’58.15”N, 25.9 m, 11 August 2016, M. Deng et al. 13980, 13982, 13983, 13984, 13987, 13989, 13990, 13997 ( CSH, IBSC) ; the same locality, 113°43’48.22”E, 21°56’47.02”N, 231.6 m, 12 August 2016, M. Deng et al. 14049, 14050, 14052, 14053, 14058, 14060 ( CSH, IBSC) .

Description:—Evergreen small trees or shrubs, 0.5–3.0 m tall. Branchlets of the current year covered with grayish-yellow short-stellate trichomes (with about 10 rays) and grayish-yellow fine lenticels. The branchlets of the second-year grayish, shortly tomentose, densely lenticellate, lenticels minute, grayish-white, prominent. Buds ovoid or ovoid-elliptic, 2.0–4.0 × 1.5–2.5 mm, reddish-brown, the scales covered with yellowish silky hair. Petiole 1.0– 2.5 cm, yellow when fresh, becoming reddish-brown when dried, covered with a dense, grayish-yellow, short-stellate trichome layer. Leaf blade ovate to lanceolate, 5.0–10.0 × 2.0–5.0 cm, thinly to thickly leathery, adaxially brightly green, abaxially grayish-green, glabrous, base broadly cuneate to rounded and slightly decurrent, apex acuminate to elongate-acuminate, margin slightly recurved, sparsely serrate from the upper half with 1–5 pair of teeth, occasionally entire; teeth apex mucronate; the mid-vein monopodial, or apical 1/3 some sympodial (flexuous), adaxially flat and abaxially raised; secondary veins 5–8 on each side of midvein, abaxially prominent, occasionally dichotomous branched. Pistillate inflorescence 0.7–3.0 cm long bearing 1–3 pistillate flowers and covered with grayish-yellow, short-stellate trichomes, but only one pistillate flower developing into mature acorn later. The pistillate flowers about 2.0 mm long, with 3 styles, the basal covered with imbricate scales; style occasionally bifid. Cupule bowl-shaped or shallowly bowl-shaped, 9.0– 13.5 mm in diam., 4.0–5.0 mm high, enclosing 1/3–1/2 of nut, outside covered with reddish-brown, obtusely triangular scales with yellowish-white hair, wall 0.3–0.4 mm thick. Nut oblong-ovoid, ca. 12.5 mm (in diam.) × 19.0 mm (long), glabrous; scar ca. 5.0 mm in diam., raised; styles 3, persistent, ca. 1.3 mm long.

Distribution and habitat:— Quercus pseudosetulosa is known only from two sites on Dawanshan Island. Its habitat area is about 450,000 m 2. The island has typical subtropical/tropical oceanic monsoon climate with warm temperature and high humidity in summer. The habitat of Q. peseudosetulosa is open rocky slope by the stream at the upper hill of the island, which is characterized by a climate that is windy and humid, but with occasional droughts in winter ( Fig. 3 ).

Vernacular name:–– China: ƑƜḧ (wan shan li).

Phenology:—The acorns of Quercus pseudosetulosa take two years to mature. The pistillate flower blooms in July and the acorns mature at later of August and September of the coming year.

Similar species:— Quercus pseudosetulosa is morphologically similar to the species of the Q. setulosa morpho-complex, resembling Q. setulosa and Q. bawanglingensis , especially in the similar leaf shape. Q. pseudosetulosa can be distinguished from Q. setulosa and Q. bawanglingensis by its usually grayish-yellow, shortly tomentose branchlets, the long petioles (1.0– 2.5 cm) usually with dense, grayish-yellow, shortly tomentose hairs, and the thickly leathery leaf blades with both flat, glabrous, glossy surfaces and recurved margins. Q. setulosa and Q. bawanglingensis have glabrous branchlets usually covered with white wax. The petioles of the two species are shorter (0.5–1.5 cm), covered with sparse, gray short tomentose hairs. The leaf blades of Q. setulosa and Q. bawanglingensis are thickly chartaceous with raised intercostal areas on the adaxial surface and grayish-yellow, fused-stellate hairs along the mid-vein and at the secondary vein axillary on the leaf abaxial surface. The three species of the morpho-complex, Q. phillyreoides Gray (1958: 406) , Q. tarokoensis Hayata (1918: 38) and Q. utilis Hu & Cheng (1951: 146) , can be easily distinguished from Q. pseudosetulosa , as they have prominently short petioles (0.2–0.5 cm). Additionally, their leaf-blade size (2–6(–8) × 1.5–3.0 cm) is much smaller than that of Q. pseudosetulosa (5.0–10.0[–11.0]) cm × 2.0–5.0 cm).

The key diagnostic features of Q. pseudosetulosa compared to the species of the Q. setulosa morpho-complex are summarized in the key to the species below:

Figures

FIGURE 1. Line drawing of Quercus pseudosetulosa. A. Fruit branch; B. Abaxial leaf surface; C. Pistillate flowers; D. Mature fruit. (Drawn by Dr. Wen SHAO from the holotype T.Y. Tu & S.C. Li LSC185).

FIGURE 2. Image of holotype of Quercus pseudosetulosa, Tu, T.Y. & Li S.C. -LSC185 (CSH).

FIGURE 3. Natural habitats and living plant of Quercus pseudosetulosa in Dawanshan Island in South China Sea. a. Landscape of the natural habitat. The yellow arrows indicate the different individuals of Q. pseudosetulosa. b. Living plant. c. Fruiting branch showing the mature acorn, scale bar = 1 cm. The red arrow shows the pistillate flowers of current year.