Oreocharis guangwushanensis morphologically resembles O. ronganensis and O. reticuliflora. The new species is vegetatively similar to O. ronganensis, but it differs from the latter in that the adaxial lip is 2-lobed to or above the middle (vs. lobed to near base), ovary with white pubescence (vs. glabrous), anthers in pairs (vs. anthers free), shorter tube (9–14 mm vs. 20 mm), shorter pistil (5 mm vs.12–15 mm) and filaments strongly twisted and bent at the top (vs. linear, straight). The new species resembles O. reticuliflora in habit, flower tube and the shape of the calyx, but differs by its pink limbs (vs. limbs with a network of violet stripes), filaments strongly twisted and bent at the top (vs. linear, straight), anthers in pairs (vs. anthers free), ovary with white pubescence (vs. glandular-pubescence) and shorter pistil (5 mm vs. 10–12 mm).

Figure 1. 

Oreocharis guangwushanensis Z.L.Li & Xin Hong A flowering plants in natural habitat B plant with pair-flowered cymes C corolla front view D opened corolla E dissected calyx lobes, outside brown with rusty strigose indumentum (3 left), inside green with brown pilose indumentum on margins (2 right) F peduncle, pedicel and young lateral branch G leaves (left: adaxial surface, right: abaxial surface) H capsule I immature pistil J immature pistil with calyx K mature pistil with calyx.

China. Sichuan province: Guangwushan Provincial Nature Reserve, 32°39'N, 106°45'E, 988 m a.s.l., growing on limestone cliffs near a river, 31 July 2020, flowering and fruiting, Hai Jun Ma, MHJ 21073102 (holotype: IBK; isotype: AHU).

Perennial herb. Leaves basal, spirally arranged; petiole 2–10 cm long, densely brown pilose and pubescent; lamina thick herbaceous, oblong to lanceolate, 4–8 × 1.6–5 cm, base slightly asymmetrical, wedge-shaped to round, margin serrate, apex obtuse to acute, concave adaxially, dark green, densely brown pubescent; prominent abaxially, light green, densely pubescent, sparsely rust-brown long pilose; ca. 5–6 pairs of lateral veins on each side of the mid rib. Cymes 1–3, axillary, pair-flowered, 1–3 branches, 1–3 (–8) flowers; peduncles 4–10 cm long, densely rusty glandular-puberulent and sparsely strigillose; bracts 2, opposite, lanceolate, ca. 4 × 0.9 mm, densely brown pilose. Pedicel 1.5–5 cm long, densely rust-brown pilose and pubescent. Calyx 5-lobed to base, narrowly lanceolate, apex acute, ca. 5 × 0.9 mm, outside brown with brown strigose indumentum, inside green, brown pilose, most densely on the margins. Corolla, pink, 1.8–2.6 cm long, densely glandular pubescent on both sides; tube cylindrical, constricted at the throat, slightly upwards curved, 9–14 mm long, 3 mm in diameter at the mouth; limb distinctly 2-lipped; adaxial lip 2-lobed to or above the middle, lobes 2 mm long, apex suborbicular, curving left and right, red stripe in the middle of the two fused upper lobes; abaxial lip 3-lobed to the base, lobes 6 mm long, oblong, with a red line in the middle of the lobes. Stamens 4, in pairs, glabrous, adnate to ca. 1–2 mm above the corolla base; filaments 5–7 mm long, strongly twisted and bent at the top, bent close to 270°, hooked, with white glands at the base, filaments of anterior pair 5–6 mm long, of posterior pair 6–7 mm long. Anthers yellow, ca. 0.8 mm long, fused by their entire adaxial surfaces. Staminode 1, linear, ca. 3 mm long, top slightly enlarged, adnate to ca. 2 mm above the corolla base; disc ring-like, about 1.5 mm high, with repand margin. Pistil mature ca. 6–7 mm long, at flower opening immature ca. 4.5 mm long, ovary linear-oblong, 2 mm long, reddish-brown, densely white pubescent. Style at pistil maturity ca. 1 mm long, densely pilose. Mature stigma with 2 lobes ca. 0.6 mm long, light green; Capsule brownish-red, ca. 2–2.5 cm × 0.2–0.3 cm, sparsely pubescent, narrowly oblong.

Flowering from May to July, fruiting from June to August.

The specific epithet is derived from the type locality, Guangwushan Provincial Nature Reserve, Sichuan province, China.

Guāng Wù Shān Mǎ Líng Jù Tái (Chinese pronunciation); 光雾山马铃苣苔 (Chinese name).

The new species has so far been found only in the type locality, Guangwushan Provincial Nature Reserve, Sichuan province, China. In the nature reserve, the average temperature is 16.2 °C, while the average annual precipitation has been calculated as ca. 1200 mm. The forest where O. guangwushanensis occurs is a monsoon evergreen broad-leaved forest.

Currently, the new species has been observed only from the type locality. After two years of careful investigation, only two small populations of O. guangwushanensis have been found. They are less than 200 m apart. In total, ca. 200 mature individuals were present within 4 km² (AOO). One population of no more than 40 individuals was growing at a higher altitude of 1124 m on a boulder near a road; the other population on a limestone wall at lower altitude 988 m by a river, close to the scenic area of the Guangwushan Provincial Nature Reserve which attracts many visitors. The locations of both populations are easily accessible and frequently passed by tourists, and thus, the number of individuals is likely to be detrimentally affected. The natural habitat could be disturbed or changed by human activities such as road expansion and other building construction. Following the IUCN Red List Categories and Criteria (IUCN 2019), the new species is provisionally assessed as Critically Endangered [CR B2ab(iii)].