Bulbophyllum chrysolabium (Orchidaceae, Epidendroideae, Malaxideae), a new species from Yunnan, China Author Li, Lin Author Ye, De-Ping Author Zeng, Song-Jun text PhytoKeys 2018 111 61 68 http://dx.doi.org/10.3897/phytokeys.111.28136 journal article http://dx.doi.org/10.3897/phytokeys.111.28136 1314-2003-111-61 22105753525B2137FE27B830FFA4FFFC 1492974 Bulbophyllum chrysolabium L. Li & D.P. Ye sp. nov. Figures 1 , 2 Diagnosis. Bulbophyllum chrysolabium is distinguished from all known congeners by having the following unique combination of features: obliquely broadly-based triangular petals with a long filiform apex; lip densely glandular papillose on both sides and conspicuously ciliolate along margins; lip auricles well developed, narrowly falcate, tapering to a long sharp point at the apex; stelidia subulate and twisted inwards, slightly exceeding operculum. Taxonomic notes. Bulbophyllum chrysolabium appears to be related to B. orientale Seidenf. ( Seidenfaden 1979 : 138), especially in narrowly falcate lip auricles and twisted stelidia, but differs in distinctly longer floral bracts (almost twice as long as the pedicel and ovary); petals with long filiform apices, a rather smaller lip (ca. 2.8 mm long), significantly glandular-papillose and ciliolate at margins; stelidia slightly exceeding operculum and distinctly longer than column. With respect to filiform petals, B. chrysolabium is also superficially similar to B. morphologorum Kraeenzl . (1908: 89), however, the latter have a fat, conical protuberance or callus on the front of the column near its base and scape much longer than rachis. In addition, it has subulate, not twisted stelidia, considerably longer than operculum; lip auricles not falcate, but rather obtuse at the apex. A detailed morphological comparison between B. chrysolabium and its allied species is presented in Table 1 . Table 1. Diagnostic morphological characters distinguishing B. chrysolabium from its two allied species.

Character	B. chrysolabium	B. morphologorum	B. orientale
Floral bract	6-6.5 mm, distinctly longer than pedicel and ovary.	4.5-5 mm, distinctly longer than pedicel and ovary.	5-6 mm, nearly as long as or slightly longer than pedicel and ovary.
Scape	5-6 cm, rachis about 6.5 cm, longer than scape	10-13 cm, much longer than rachis	4-8 cm, rachis about the same length
Dorsal sepal	oblong-ovate or narrowly ovate, apex shortly aristate or apiculate, 4.5-5 mm x 1.0-1.5 mm	ovate, apex acute, 6.5-7 mm x 2.5-3 mm	broadly ovate, apex acute, ca. 7.0 x 3.5 mm,
Lateral sepals	obliquely oblong-ovate, margins strongly involute, with the apex shortly caudate, 5.5-6 mm x 2.0-2.5 mm	obliquely ovate-lanceolate, margins not involute, apex acute, 7.5-8.0 x 3.5 mm	obliquely ovate-lanceolate, margins not involute, apex acute, ca. 8.0 x 4.5 mm
Petals	apex with long filiform apices, ca. 3.0 mm long, usually contorted to spirally twisted	apex with filiform apices, ca. 1.8 mm long, not twisted	apex with cuspidate apices, ca. 0.8 mm
Lip	ca. 2.8 mm long, significantly glandular-papillose and ciliolate at margins	ca. 5 mm long, not papillate or papillose at margins	ca. 6 mm long, somewhat papillate at margins, not ciliolate
Lip auricles	narrow falcate, long acuminate with a sharp point	not falcate, rather obtuse at apex	narrow falcate, apex apiculate and unequally 2- or 3-toothed
Column callus	absent	present, conical	absent
Stelidia	subulate and twisted, exceeding operculum	subulate but not twisted, exceeding operculum	subulate and twisted, as long as or shorter than operculum

Type. CHINA. Yunnan Province. Menglian Dai, Lahu and Va Autonomous County (referred to as Menglian County), 1400-1600 m alt., 23 May 2014, L. Li 1209, (holotype, IBSC! isotype, IBK!). Description. Epiphytic herbs. Rhizome rigid, creeping, 2-3 mm thick. Pseudobulbs borne on rhizome at an interval of 3-5 cm, ovoid to narrowly ovoid, 2.2-3.5 cm high, base often covered with remnant fibrous sheaths. Leaf apical, single, coriaceous, oblong to linear-oblong, 12-14 cm x 1.8-2.2 cm, subsessile, apex retuse or minutely notched. Inflorescences developing from base of pseudobulb, with pendulous densely many-flowered raceme; scape 5 to 6 cm long, nearly completely enveloped by 4 or 5 sterile, broadly ovate sheaths; sheath 1.5-1.8 cm long, scaled, light brownish; rachis about 6.5 cm long, with many flowers spirally arranged into a compact spike-like cylindrical raceme, opening simultaneously; floral bracts light brownish, dry papyraceous, oblong-lanceolate, ca. 6.5 mm long, almost twice as long as the pedicel and ovary, apex apiculate; pedicel and ovary ca. 3.5 mm, longitudinally slightly grooved. Flowers resupinate, not much opening, with unpleasant fishy smell. Sepals 3-6-veined, greenish-yellow, without spots or stripes. Dorsal sepal oblong-ovate or narrowly ovate, 4.5-5.0 mm x 1.0-1.5 mm, 3-veined, abaxially sparsely papillate, apex shortly aristate or apiculate, often recurved. Lateral sepals obliquely oblong-ovate, 5.5-6 mm x 2.0-2.5 mm, 5-6-veined, abaxially sparsely papillate, base adnate to column foot, margins strongly involute, with the apex shortly caudate, loosely adhering along the lower edges, forming an ovoid sac. Petals pale greenish-yellow, obliquely and broadly-based triangular, apex long acuminate, tapering into a long filiform or threadlike tail, usually contorted to spirally twisted, 2.0-2.2 mm x 0.8-1.0 mm near the base, with a tail 2.8-3.0 mm long, margins somewhat irregularly denticulate or erose. Lip yellowish-orange or deep golden yellow, fleshy, oblong narrowly ovoid, 2.5-2.8 mm x 1.3-1.5 mm, mobile on a thin ligament, recurved near the base, conspicuously auriculate at the base; disc with a longitudinal central groove, apex rounded or obtuse; auricles narrowly falcate, arching forward and gradually tapering to a long sharp point at the apex; densely glandular pap illose on both sides and conspicuously ciliolate along margins, whitish. Column greenish-yellow, subcylindric, 2.0-2.2 mm tall; foot ca. 1.5 mm; stelidia well-developed and subulate, ca. 1.2 mm, often twisted inwards, equalling or slightly exceeding operculum, with a sharp point along the upper margin. Anther abaxially with a rounded crest, golden-yellow. Pollinia 4, the inner ones more than half as long as the outer ones. Figure 1. Bulbophyllum chrysolabium. A Habit B Flower, lateral view C Flower, frontal view D Dorsal sepal, petals and lateral sepals, adaxial view E Lip, lateral view F Lip, ventral view G Pollinia H Operculum, ventral view I Column, ventral view J Column and lip, lateral view. Scale bars: 2 cm ( A ), 2 mm ( B-D ), 1 mm ( E-F , I-J ), 0.2 mm ( G-H ). Drawn by Yun-Xiao Liu. Distribution and habitat. So far known only from Menglian County in southwest Yunnan Province, China, growing as an epiphyte amongst mosses on the tree trunk near the edge of river in rather exposed circumstances in subtropical evergreen broad-leaved forest. Etymology. The specific epithet comes from the Ancient Greek word chryso - "golden" and the Latin derived labium "labellum" , referring to the golden-yellow lip of the type. Phenology. Flowering observed in December. Conservation status. Bulbophyllum chrysolabium is known only from its type locality, where it is represented by a single population of about 30-50 individual plants or clumps. The extent of occurrence (EOO) of the species cannot be estimated and its area of occupancy (AOO) is estimated to be 4 km2, which falls within the thresholds for Critically Endangered under criterion B2. Additional individuals of this species may yet be found in adjacent areas as the investigation continues. The location is relatively inaccessible to casual hikers and the potential for habitat destruction is limited, but it is not in a national reserve or other kinds of protected areas. Fortunately, a few individuals were brought into cultivation at SCBG. Although there is limited data to determine its actual distribution range, biology and threats, the current available information (one location in a non-protected area and AOO less than 10 km2) led us to assign a preliminary status of Critically Endangered [CR B2ab(iii)] according to the IUCN Red List Categories and Criteria ( IUCN 2017 ). Figure 2. Bulbophyllum chrysolabium. A Habitat B Inflorescences C Close-up of inflorescence D Flower, lateral view showing floral bract E Flower, frontal view F Dorsal sepal, petal and lateral sepal, abaxial view G Lip, ventral view H Column and lip, lateral view. Scale bars, 1 mm ( G ), 2 mm ( D-F , H ).