Vernicia calcicola Y. Feng Huang & D. X. Nong, 2023

Nong, Dong-Xin, Hu, Ren-Chuan, Huang, Yun-Feng & Yu, Li-Ying, 2023, Vernicia calcicola (Euphorbiaceae), a new species from limestone areas of Guangxi, China, Phytotaxa 587 (2), pp. 205-210 : 205-208

Vernicia calcicola Y. Feng Huang & D. X. Nong , sp. nov. ( Figs 1 & 2 )

Diagnosis:―Morphologically similar to V. fordii (Hemsl.) Airy Shaw , different by its stalked, connate, columnar glands adaxially at junction with blade, inflorescences usually unisexual, pistillate inflorescences with a single flower, calyx apex apiculate, slightly (2–)3 or 4-fid, ovary glabrous and fruit stalk stout.

Type:― CHINA. Guangxi Zhuang Autonomous Region , Napo County, Pingmeng Town , Liusha Village , 22°58′26.93″N, 106°00′09.42″E, growing in primary or secondary broad-leaved evergreen forests, 702 m a.s.l., 16 Apirl 2018, fl. D. X. Nong 451026180416006LY (Holotype GXMG!; isotype GXMG!, IBK!); the same locality, 16 Apirl 2018, fl. D. X. Nong 451026180416005LY (Paratype GXMG!); the same locality, 31 May 2017, fr. Y. Feng Huang & R. C. Hu HYF170531020 (Paratype GXMI!, IBK!)

Shrubs or trees, usually dioecious, sometimes monoecious, deciduous, up to 7 m tall; bark gray; branches glabrous, with clear latex and sparsely raised lenticels. Stipules triangular-ovate, 3–5 × 2–3 mm, caducous. Petiole terete, 6–17 × 1.5–2 mm, glabrous, with 2 connate, stalked glands adaxially at junction with blade; glands columnar, 1.5–2 × 1–1.5 mm, caducous. Leaf blade broadly ovate, leathery, glossy, 9–18 × 8–16 cm, sparsely puberulous on both side when young; base cordate to peltate; margin entire or occasionally shallowly 3-fid and with connate, stalked glands in each sinus; apex and lobes acuminate or obtusely acuminate; palmate veins 5, with 4–7 major lateral veins per side of the midrib, prominent on both sides. Inflorescences produced with new leaves, usually unisexual. Staminate inflorescences many-flowered, corymbiform thyrses. Pistillate inflorescences single flower. Buds long ellipsoid, 25–30 × 7–10 mm; flowers white, greenish then reddish in the centre, fragrant; calyx green, oval, 8–10 × 9–12 mm, apex apiculate, slightly (2)3 or 4-fid, pubescent outside and apex inside; petals obovate-spathulate, 3–4.5 × 2.5–3 cm, base clawed, apex rounded. Staminate flowers: pedicel 0.5–0.7 cm long, disc glands subulate, 3–4.5 × 0.5–1 mm, acute; stamens 10–12, in 2 whorls, the outer ones free from each other but basally adnate to the petals, 1–1.5 cm long, the central staminal column ca. 2.2 cm long, fused for over at least two thirds of their length; filaments glabrous, anthers 3–4 × 1–1.2 mm, light yellow. Pistillate flowers: pedicel stout, glabrous, 0.5–0.8 cm long, disc glands 2–3 × 0.8–1 mm, ovary oblong-ovoid, narrowing into the styles, 3–5-locular, 5–7 × 5–6 mm, styles 3, bifid, 6–8 mm long, glabrous. Fruit stalk stout, 1.5–2 cm long, 0.8–1 cm thick, drupes ovoid, 3–5 cm in diam., glabrous, with sparsely reticulate wrinkles and 3 distinct longitudinal grooves, 3-seeded, basally stiped, apically sharply pointed, 0.7–1.5 cm long. Seeds compressed globose, 2–2.4 × 1.8–2 cm; seed coat thicker, smooth.

Additional specimens examined:― CHINA, Guangxi Zhuang Autonomous Region, Napo County: 17 Apirl 2008, Y. Feng Huang 18133 (GXMG!); 17 Apirl 2008, Y. Feng. Huang et al. 18144 (GXMG!); 13 October 2014, D. X. Nong et al. 451026141013014LY (GXMG!); 18 June 2010, W. B. Xu & R. H. Jiang 10759 (IBK!); 18 June 2010, W. B. Xu & R. H. Jiang 10762 (IBK!), R.C. Hu, X. C. Lan & P. Yang HRC160307002 (GXMI!); Jingxi City: 25 June 2010, L. Y. Yu & J. X. Liang YLYJX0166 (GXMG!); 29 March 2010, J. Huang et al. 21813 (GXMG!); 22 October 2011, D. X. Nong et al. YLYJX0370 (GXMG!); 14 March 2013, H. Z. Lv et al. 451025130314038LY (GXMG!).

Etymology:―The specific epithet refers to the habitat of the new species.

Phenology:―Flowering from March to April, fruiting from July to October.

Distribution and habitat:― Vernicia calcicola is currently known in a small area near Sino-Vietnam border between Guangxi and Cao Bang provinces. It grows on limestone slopes in primary or secondary broad-leaved evergreen forests, between 588 and 973 m a.s.l., associated with Itoa orientalis Hemsl. , Sterculia euosma W. W. Smith , Wrightia sikkimensis Gamble , Toxicodendron wallichii var. microcarpum C. C. Huang ex T. L. Ming , Diospyros siderophylla H. L. Li , Nephrolepis cordifolia (L.) C. Presl.

Taxonomic relationships:―Among the three widely cultivated species in China and Japan, V. calcicola most closely resembles V. fordii in the tree shape and stipules shape, the main difference between the two species are the glands at the apex of petiole (columnar, connate and stalked vs cushion-shaped, sessile), calyx (apex apiculate, slightly (2–)3 or 4-fid vs apex obtuse, 2 or 3-fid), florescences (unisexual vs bisexual), ovary indumentum (glabrous vs pubescent) and fruit stalk (stout vs slender). Besides, the stems of young trees thicker at base probably to adapt the water shortage in limestone areas ( Figs. 2K ).

Although the four Vernicia species are closely related, there are still many morphological differences between them, such as the stipules, glands at the apex of the petiole, inflorescence, fruit stalk and fruit surface ( Figs. 2 & 3 ). Details of the morphological differences between V. calcicola , V. fordii, V. Montana (1790: 587) and V. cordata (1967: 394) are showed in Table1 .

Figures

FIGURE 1. Vernicia calcicola: A fruiting branch; B calyx; C petal; D pistil and glands; E stamens and glands; F seed.

FIGURE 2. Vernicia calcicola: A flowering plant; B fruiting plant; C young fruit; D stipules; E buds; F staminate flowers; G pistillate flower; H pistillate flower opened showing pistil, glands and calyx; I staminate flower opened, showing stamens, glands and calyx; J glands; K young plant; L fruit.

FIGURE 3. Vernicia montana: A young plant; B staminate inflorescence; C pistillate inflorescence; D fruiting branch; E stipules; F glands; V. fordii: G glands; H stipules; I fruit; J inflorescence with pistillate flowers and staminate flowers; K staminate flowers.