Epimedium zhaotongense G.W.Hu, 2017

Epimedium zhaotongense G.W.Hu View in CoL , sp. nov. ( Figures 1 View FIGURE 1 & 2 View FIGURE 2 )

Diagnosis: — Epimedium zhaotongense differs from E. membranaceum ( Figure 3 View FIGURE 3 ) by its simple raceme, ovate-deltoid to lanceolate leaflets with appressed stout hairs on the abaxial surface, smaller flowers (2–3 cm in diam.), the length ratio of inner sepals to petals (1/3 to 1/4), and ovate inner sepals.

Type: — CHINA. Yunnan Province: Zhaotong City, Zhaoyang District, Sujiayuan Township, Guanzha Reservoir , elev. 2150 m, 12 April 2011, G. W. Hu HGW-01054 (holotype, HIB! ; isotypes, HIB! )

Perennial herb 0.5 m high, rhizome long-creeping and branched, up to 0.2 cm in diam. Leaves basal and cauline, trifoliolate. Leaflets narrowly ovate-deltoid to lanceolate, 3.7–8.2 × 2.2–3.4 cm; apices long acuminate; bases deeply cordate, terminal leaflet with equal, round lobes, lateral leaflets conspicuously oblique with inner lobes rounded or acute, outer lobes larger, rounded, acuminate or acute; margins spiny-serrate; subleathery; adaxial surface glabrous, abaxial surface thickly furnished with short appressed fairly stout hairs. Flowering stem 40 cm or longer, with two opposite leaves. Inflorescence racemose, loosely with 8–15 flowers, glandular; pedicels 1.2–2.2 cm long. Flowers yellow, 2–3 cm in diam. Outer sepals blunt, obovate, 2–4 mm long. Inner sepals ovate, reddish, 5–7 × 2–4 mm, 1/3 to 1/4 length of petals. Petals yellow, much longer than inner sepal, horn shaped, tapering from the swollen base, curving outwards, 1.5–2.2 cm long, base without lamina. Stamens ca. 3 mm; filaments ca. 1 mm; pollen yellow.

Etymology: —The epithet zhaotongense is derived from the name of the type locality, Zhaotong City of Yunnan Province, China.

Geographical distribution: —At present, Epimedium zhaotongense is only known from Zhaotong, Yunnan, China. Only two sites (ca. 12 km away from each other) of E. zhaotongense were found in a relatively narrow area, although extensive field search was conducted for four times. It is possible that E. zhaotongense occurs in adjacent area in northeastern Yunnan that is yet to be explored.

Ecology: —It often occurs in the relatively dry habitats in forest and thicket margins on the slopes, at elevations between 2010 and 2150 m.

Phenology: — Epimedium zhaotongense is known to flower in April in cultivation.

IUCN Red List Category: —The status of Epimedium zhaotongense can be classified as Critically Endangered (CR B2a; B2b(ii)), based on current information and IUCN Red List criteria ( IUCN 2001). But more extensive fieldwork in surrounding similar habitats is needed to accurately assess its conservation status.

Additional specimens examined (paratypes): — CHINA. Yunnan Province: Zhaotong City, Zhaoyang District, Sujiayuan Township, Buchu Village, elev. 2010 m, 29 April 2009, Y. J. Zhang 337 (HIB!). Yunnan Province: Zhaotong City, Zhaoyang District, Sujiayuan Township, Guanzha Reservoir, elev. 2150 m, 11 April 2011, G. W. Hu HGW-00625 (HIB!).

Abaxial leaflet micromorphology: —The two species considered here both possess nonglandular hairs on the abaxial surface of the leaflets. The nonglandular hairs of abaxial leaflet of E. zhaotongense is ca. 0.4 mm long and composed of 4 cells. It is characterized by a long and thick terminal cell and a short stalk. The terminal cell has a length of eight to ten times of the stalk which is composed of three basal cells. The stalk is constricted and bends to the leaf surface, which makes the whole hair appressed to the abaxial leaflet surface. However, as to E. membranaceum , the hair is ca. 1 mm long and composed of 5–8 cells. Besides, the length of the terminal cell is nearly equal to the adjacent one, and there is a distinct joint between the adjacent cells. The hairs are erected or patulate and sparsely scattered on the abaxial leaflet surface. The pictures of abaxial leaflet morphology of this two species are shown in Figure 4 View FIGURE 4 .

Affinities: — Epimedium zhaotongense has petals bearing long slender spur without laminae, and should be grouped to E. sect. Diphyllon ( Komarov 1908: 134) Stearn (2002: 48) ser. Dolichocerae Stearn (1938: 490) . In E. ser. Dolichocerae, the new species is most similar to E. membranaceum , but can be distinguished by its simple raceme, ovate-deltoid to lanceolate leaflets with appressed stout hairs on abaxial surface, smaller flowers (2–3 cm in diam.), the length ratio of inner sepals to petals (1/3 to 1/4), and ovate inner sepals. ( Table 1 View TABLE 1 ). In addition, the mircomorphology of abaxial leaflet surface also exhibits differences between two species.