Euphorbia maoershanensis F. N. Wei & J. S. Ma, 2013

Ma, Jin-Shuang, Liu, Yan & Wei, Fa-Nan, 2013, A new species of Euphorbia (Euphorbiaceae) from Guangxi, China, Phytotaxa 87 (3), pp. 45-49 : 45-48

Euphorbia maoershanensis F. N. Wei & J. S. Ma , sp. nov. ( Figs. 1 & 2 )

The new species is similar to other members of sect. Holophyllum , but has leaves with a comparatively long petiole, which is a very rare case at least among species of Euphorbia from East Asia; and it is also similar to Euphorbia soongarica Boissier (1860: 32) but different from the latter by fruits that are smooth, leaves with entire margin and revolute when dried, and the caruncle of seeds not stipitate.

Type: — CHINA. Guangxi: Xing’an County, Mao-er-shan (Mt. Cat Ear), Natural Reserve , top of mountain, 2080 m, 23 June 1997, Li Guang-Zhao 15042 (holotype PE!) .

Herb, perennial, smooth and glabrous. Root terete, 30–50 cm × 5–10 mm. Stems erect, several clustered, 30–50 cm × 4–8 mm, with several branches in the upper part. Stem leaves alternate; petiole c. 5–7 mm long; leaf blade ovate-elliptic, 4–6 × 0.3–0.8 cm, apex acuminate or acute, base attenuate, margin entire, light bluegreen at maturity, and slightly revolute when dried; lateral veins pinnate, 5–8 pairs; primary involucral-leaves 3–5, ovate to oblong-ovate, 5–10 × 4–8 mm; primary rays 3–5; secondary involucral-leaves 2–3, similar to primary involucral-leaves, light yellow to yellow. Cyathia stipitate, ca. 3 mm long; involucre campanulate, ca. 2.5 × 2–2.5 mm, 5 lobes, rounded to ovate-oblong, ciliate at inside margin; glands 5, rounded, yellow when fresh but light brown when dry; male flowers 4–6, exserted from cyathium; ovary smooth and glabrous, pedicel up to 5 mm, exserted from cyathium; styles 3, connate at base, persistent; stigmas ca. 3 mm long, 2- lobed. Capsule subglobose or globose, 4–5 × 4–5 mm, smooth; pedicel ca. 3.5 mm long. Seeds ovoid-globose, 2.5–3 × ca. 3 mm, dark brown; caruncle ovoid to heart-shaped without stipe.

Paratypes: — CHINA. Guangxi: Xing’an County, Mao-er-shan (Mt. Cat Ear), Natural Reserve , top of mountain , 2100 m, 28 July 1937, Zhong Ji-xin (Tsoong Chi-Hsin) 83469 ( IBK!) , near local television station, 2140 m, 7 May 1979, Li Guang-Zhao & Huang Fu-Xiang 54 ( IBK!) , 28 April 1980, Li Guang-Zhao & Lu Bin 10419 ( IBK!) , 10 May 1982, Li Guang-Zhao 11270 ( IBK!) , 16 May 1986, Li Guang-Zhao 12202 ( IBK!) , 26 July 1989, Li Guang-Zhao 12344 ( IBK!) , 17 September 1993, Li Guang-Zhao 12942 ( IBK!) , September 17, 2010, Liu Yan L1546 ( IBK!) ; Xing’an County, without location, ca . 2000 m, July 25, 1989, Wen Hequn w096 ( K!) .

Ecology: —Flowering from April to July, and fruiting from June to October. The new species grows in the understory of primary subtropical evergreen forests above 2000 m, and along with the trees species Symplocos botryantha Franch. and Rhododendron pachyphyllum W. P. Fang , the shrub species Rh. orbiculare Decne. subsp. cardiobasis (Sleumer) D. F Chamb. , Berberis julianae C. K. Schneid. , Litsea rubescens Lecomte , Enkianthus chinensis Franch , Camellia pitardii Cohen-Stuart , Oyama sieboldii (K. Koch) N. H. Xia & C. Y. Wu , Vaccinium sinicum Sleumer , Rh. levinei Merr. , Rh. oligocarpum W. P. Fang & X. S. Zhang , and herbs such as Peucedanum praeruptorum Dunn and others.

Etymology: —Named after the local mountain name, Mao-Er-Shan (in Chinese, Mt. Cat Ear in English), at 2140 m, Xing’an County, Guangxi, China, where the species is endemic.

Systematic position: —This species is indeed a very strange one among the East Asian taxa of Euphorbia , but possibly placed within sect. Holophyllum since its glands are rounded and fruits are smooth. However, further studies are needed for further details, incuding molecular work. It is also similar to Euphorbia soongarica by, e.g. the leaves with long petiole, which is not known from any species of sect. Holophyllum from eastern Asia.

Distribution and conservation status: —This is a very rare species since it is only found on a single isolated mountaintop, and we see no apparent potential of range expansion. According to the IUCN redlist criteria ( IUCN 2001), this should be treated as “Vulnerable”, since not only is the wild population very small with isolated distribution, but the habitat is threatened by both tourism and local development. The site is near an antenna set up by the local television station. The Mt. Mao-Er-Shan (Mt. Cat Ear) is important in forestry and in hydrology since it is the main source of the Li River, known for its tremendous tourist value especially near the city of Guilin, Guangxi, China. Therefore we strongly advocate for the species to be immediately added to the Red List in China once it is officially published.

Figures

FIGURE 1. A, shoots and root; B, leaf base (abaxial); C, cyathium; D, fruit; E, seed; F, caruncle (illustrated by Yunxi Zhu, A–B & D–F from Zhong Ji-xin 83469, C from Li Guang-Zhao & Huang Fu-Xiang 54).

FIGURE 2. A–E, various involucral-leaves, with young cyathia, male and female flowers; F, young fruits; G, fruit and seed (with caducous caruncle); H, habit; I, specimen (Li Guangxi 15042, PE); J, specimen (Wen Hequn w096, K).