China. Fujian: Pingnan County, Shuangxi Town, on rock along Yuanyan River, 800–900 m, 27°01'N, 119°05'E, 23 June 2013, J.F. Liu 201312 (holotype: FAFU!; isotype: NOCC!).

Bulbophyllum pingnanense is similar to B. brevipedunculatum T.C. Hsu & S.W. Chung and B. albociliatum (T.S. Liu & H.Y. Su) K. Nackejima. It differs from B. brevipedunculatum by having a longer dorsal sepal with either an obtuse or an acute apex and longer white ciliate on margins; longer and lanceolate lateral sepals; and glabrous lip. It can be distinguished from B. albociliatum by its shorter inflorescence, a longer dorsal sepal with either an obtuse or an acute apex.

Epiphytic herb. Rhizome creeping, slender, 0.6–1 mm in diam. Pseudobulbs 0.6–2.5 cm apart on rhizome, obovate-elliptic, 0.5–1.7 cm, 3–6 mm in diam., with a terminal leaf. Leaf sessile; blade oblong to linear-oblong, 1.8–6.6 × 0.6–1.2 cm, apex obtuse to retuse. Scape arising from base of pseudobulb, ca. 1.1 cm, umbel 3–5 flowered; peduncle slender, ca. 0.6 mm in diam., with 3 or 4 sheaths; floral bracts triangular, 2–3 mm. Pedicel and ovary ca. 4 mm. Flowers orange red. Dorsal sepal concave, ovate, abaxially papillose, ca. 5 × 3 mm, margins long white ciliate, apex obtuse or acute; lateral sepals lanceolate, abaxially papillose, 10–12 × ca. 2 mm, slightly twisted near the base, with their upper and lower edges often loosely adhering, margins glabrous, apex acute. Petals ovate, 2.7–3.0 × 1.2–2.0 mm, margins long white ciliate, apex rounded. Lip recurved, ovate-triangular, ca. 3 mm, abaxially deeply grooved, base attached to end of column foot by a mobile joint. Column yellow, subterete, ca. 1–2 mm, with a distinct foot, ca. 1.0–2.5 mm, conspicuously winged; stelidia triangular, slender; anther cap subglobose; pollinia 4, in 2 pairs, without appendages.

Figure 1. 

Bulbophyllum pingnanense sp. nov. A plant B flower C dorsal sepal D lateral sepal E petal F lip G pollinia and anther cap H lip, column, pedicel and ovary, side view (Drawn from the holotype by Bi-Dan Lai).

Figure 2. 

Bulbophyllum pingnanense J.F. Liu, S.R. Lan & Y.C. Liang. A habitat and habit B–D flower E dorsal sepal F lateral sepal G petal H lip I lip, column, pedicel and ovary, side view J pollinia and anther cap.

Bulbophyllum pingnanense is so far only known within Pingnan, Fujian, China (Fig. 3). It is epiphytic on steep rock in the edge of evergreen coniferous and broad-leaved mixed forest, which is mainly composed of Castanopsis eyrei (Champ. ex Benth.) Hutch. (Fagaceae), Cunninghamia lanceolata (Lamb.) Hook. (Taxodiaceae). Other orchids, Amitostigma gracile (Bl.) Schltr., Pholidota cantonensis Rolfe, Cymbidium floribundum Lindl. and Pleione formosana Hayata, were found growing nearby this new species.

Figure 3. 

Distribution of Bulbophyllum pingnanense, B. brevipedunculatum and B. albociliatum.

Flowering from June to July.

Bulbophyllum pingnanense is known only from the type locality, and only one population of ca. 3000 individual plants was discovered in a small area of ca. 0.002 km² during two years of botanical surveys. Based on the extent of occurrence estimated to be less than 100 km² (CR B1) and the area of occupancy less than 10 km² (CR B2), species existing at a single location (CR B1a + B2a), B. pingnanense is assigned a preliminary status of Critically Endangered (CR B1a + B2a) according to the IUCN Categories and Criteria (IUCN 2012). In addition, the plants of Bulbophyllum are used as herbal medicine in the locality. It is possible that B. pingnanense might also be collected for using as herbal medicine. Therefore, immediate conservation strategy should be taken.

The species epithet refers to Pingnan County where this new species was found.

Several morphological characters, such as the dorsal sepal being much shorter than the lateral sepals, and the lateral sepals twisting and connected, indicate that this species belongs to sect. Cirrhopetalum. Bulbophyllum pingnanense is closely related to B. brevipedunculatum, but it can be distinguished by having a longer (ca. 5 mm vs. ca. 3.5 mm) dorsal sepal with either an obtuse or an acute (vs. rounded) apex and longer white ciliate (vs. short white ciliate) on margins, longer (10–12 mm vs. 5–7 mm) and lanceolate (vs. near rectangular) lateral sepals, glabrous (vs. adaxially papillose) lip. In addition, the two species had different flowering seasons that never overlapped (June–July vs. March–April), and the nearest distance between them is ca. 370 km, separated by the sea (Fig. 3). The new species is also closely related to B. albociliatum, but it can be distinguished by having a shorter (ca. 1.1 cm vs. 4–6 cm) inflorescence, and a longer (ca. 5 mm vs. 3–4 mm) dorsal sepal with either an obtuse or an acute (vs. rounded) apex; the nearest distance between the two species is ca. 350 km, separated by the sea (Fig. 3).