Styrax rhytidocarpus W. Yang & X. L. Yu, 2015

Zhou, Hui, Yang, Wen, Li, Ming & Yu, Xun-Lin, 2015, Styrax rhytidocarpus (Styracaceae), a new species from Hunan, China, Phytotaxa 230 (1), pp. 87-91 : 88

Styrax rhytidocarpus W. Yang & X. L. Yu , sp. nov. ( Figs. 1–2 )

Diagnosis: —The new species is similar to Styrax odoratissimus in leaf blade size and shape, and the presence of curved filaments, but differs in its glabrous peduncles, bracts, and pedicels; 1.7–2.0 × 0.8–1.3 cm corolla lobes; bowl-shaped and deeply rugose persistent calyx; thick, fleshy, and rugose fruits with slightly curved and long-rostrate fruit apex; and ridged and densely stellate-hairy seeds. More detailed morphological comparison between these two species summarized in table 1.

Type: — CHINA. Hunan Province: Linwu Xian, Xishan Yaozu Zizhixiang , ca. 960 m, 25°14 ′ 37.09 ″ N, 112°25 ′ 25.58 ″ E, 28 August 2011, W. Yang 11082801 (holotype, CSFI!; isotypes, CSFI!, IBSC!) .

Paratype: — CHINA. Hunan Province: Linwu Xian, Xishan Yaozu Zizhixiang, ca. 960 m, 25°14 ′ 37.09 ″ N, 112°25 ′ 25.58 ″ E, 28 April 2014, D. Zhou & H. Zhou 14042802 ( CSFI!, IBSC!).

Description

Deciduous shrubs or small trees, to 7 m tall. Branchlets brown. Leaves alternate; petioles 4–9 mm long, glabrous; leaf blades elliptic or elliptic-oblong, 6–15(–20) × 3–9 cm, papery, adaxially sparsely with hairs along veins, abaxially glabrous, base cuneate, margin shallowly serrate, apex acuminate to caudate, slightly curved, lateral veins 5–7 pairs, adaxially impressed, abaxially prominent, tertiary and quaternary veins reticulate. Inflorescence racemose, terminal, 4–11 cm long, 4–9-flowered (sometimes 2–3 flowers grouped in leaf axils), peduncle short and glabrous. Pedicel 4–7 mm long, glabrous. Bracteoles subulate, 1–2 mm long, glabrous. Flowers 2.2–2.7 cm long. Calyx (including tube) cupuliform, 4 × 5–7 mm, outside with short hairs, brown-lepidote at base, inside glabrous, irregularly 5–8-toothed, teeth 2 × 3 mm. Corolla white, 1.8–2.3 cm long; tube 3 mm long; lobes oblong-ovate, 1.7–2.0 × 0.8–1.3 cm, both surfaces sparsely with short hairs, floral aestivation imbricate. Stamens 10, equal in length, 1.7–2.0 cm long; filaments 1.0 cm long, flexuous, densely with white stellate hairs at middle, sparsely hairy elsewhere, basally connate and adnate to corolla; anthers 7–9 mm long, sparsely with white stellate hairs, oblong-elliptic to lanceolate, thecae parallel, linear, dehiscence introrse. Ovary partly inferior but appearing superior, 1.5 × 3 mm, hairy. Style filiform, 1.4–1.7 cm long, hairy. Stigma punctiform, ca. 2 mm long. Drupe ovoid-conical, 2.5–3 × 1.5 cm, rugose, fleshy, outside yellow-lepidote, apex slightly curved with a rostrum ca. 5 mm long; persistent calyx bowl-shaped, brown, deeply rugose, ca. 1.2 × 1.2 cm. Seeds 1(–3), ovoid, ca. 1.0 × 0.7 cm, dark brown to black, hilum basal, large; testa tuberculate and ridged, densely with brown stellate hairs.

Distribution and Habitat: —The new species is known only from the type locality in Linwu county of Hunan Province, at elevation ca. 960 m. The type locality is located at the northern slope of the middle of the Nanling Mountains. It grows in bamboo and broad-leaved mixed forest and is mainly distributed along both sides of a moist gulley. The habitat is dominated by Styrax japonicus Siebold & Zuccarini (1837: 53) ( Styracaceae ), Calanthe graciliflora Hayata (Orchidaceae) , Loropetalum chinense (R. Br.) Oliv. ( Hamamelidaceae ), Phyllostachys edulis (Carrière) J. Houz. ( Poaceae ), Pleioblastus amarus (Keng) Keng f. ( Poaceae ) and Weigela japonica Thunb. var. sinica (Rehder) L. H. Bailey ( Caprifoliaceae ).

Phenology: —Flowering from April to May; fruiting from May to October.

Etymology: —The specific epithet “ rhytidocarpus ” is derived from Greece “ rhitido” meaning wrinkled and “ carpus ” meaning fruits because of its rugose fruits.

IUCN Red List Category: —The only known population consists of ca. 100 mature individuals scattered along both sides of the gulley where the species grows. Human activity is frequent around this population, e.g., digging bamboo shoots and cutting firewood. In accordance with the IUCN Red List Criteria ( IUCN 2014), the new species should be regarded as Critically Endangered (CR B2c i, iv) because of its limited populations and vulnerable habitat.

Figures

FIGURE 1. Styrax rhytidocarpus W. Yang & X. L. Yu: A. habit; B. pedicel, calyx and gynoecium; C. opened flower showing stamens; D. stamens in dorsal (left) and ventral view (right); E. fruit, including persistent calyx; F. seed. (based on both type (fruit specimens) and paratype (flower specimens)).

FIGURE 2. Styrax rhytidocarpus W. Yang & X. L. Yu: a. flowering branch; b. pedicel, calyx and gynoecium; c. flower bud and partly open flower; d. flower, apical view; e. opened flower showing stamens; f. fruiting branchlet; g. fruits; h. longitudinal cross section of fruit; i. and j. seeds.