A new species of Macroclinium (Orchidaceae: Oncidiinae) from Andean Venezuela with brief comments on the biogeography of the genus Author Fernández-Concha, German Carnevali Herbario CICY, Centro de Investigación Científica de Yucatán, A. C., A. P. 87, Cordemex, Mérida 97310, Yucatán, México. Telephone (99 - 99) 81 - 39 - 23; facsimile (99 - 99) 813900. carneval @ cicy. mx Author Cetzal-Ix, William El Colegio de la Frontera Sur (ECOSUR), Unidad Chetumal, Av. del Centenario, km 5.5, Chetumal 77000, Quintana Roo, México. rolito 22 @ hotmail. com text Phytotaxa 2012 2012-01-04 40 12 20 http://biotaxa.org/Phytotaxa/article/view/phytotaxa.40.1.2 journal article 6134 10.11646/phytotaxa.40.1.2 6e1d7e6d-1e0e-4628-8ce9-83bf62d5fe90 1179-3163 4894761 Macroclinium larense Carnevali & Cetzal , sp. nov ( Fig. 1 ) Type :— Venezuela , Lara , Distrito Jiménez : Parque Nacional Yacambú , 10–14 km by road SE of Sanare , ridges of Fila Potreritos, between Alto del Viento and El Volcán ; 9°41–42’ N , 69°37–35’ W , 1800–2100 m , 25–27 October 1982 , Davidse & González 21237 ( holotype VEN !, isotype MO !) . Species haec Macroclinio borjaense affinis sed labello ( 5.9–6.1 mm long vs. 10.5 mm in M. borjaense ) petalaque (6.0 mm in M. larense vs. 11mm in M. borjaense ) breviore, unguiculis proportione longiore (isthmo subaequante vs. breviore in M. borjaense ) Plant epiphytic; roots filiform, glabrous; pseudobulbs ovoid, 4.0 × 3.5 mm , laterally compressed, partially clothed by 4 or more leaf-bearing sheaths; leaves unifacial, laterally flattened, lanceolate to elliptical, 20 × 5 mm , the surface smooth; inflorescence compressed-racemose; peduncle up to 20 mm long, with 3 triangular bracts, 2–3 mm long; rachis abbreviate and thus subumbellate; floral bracts lanceolate to cuneate, 2.0–2.5 × 1.0 mm; ovary subclavate, 3.9–5.0 mm long including the pedicel; flowers resupinate with widely spreading, pale violet perianth parts; sepals elliptical-lanceolate acute or broadly obtuse, dorsal sepal 5.5–6.0 × 1.3–1.5 mm , lateral sepals 5.6–5.8 × 0.8–0.9 mm , free, slightly longer than the dorsal and thinner in texture; petals 4.0–4.2 × 1.2–1.3 mm , similar to the sepals; labellum 5.9–6.1 mm long, 1.8–2.0 mm wide across the retrorse basal lobules of the central lobe, long-clawed, the claw 1.8–2.0 mm long, labellar blade (central lobe) articulate with the claw; in general outline hastate and pentalobate, basal and lateral lobes sagittate, apical lobe acute, the isthmus between the two set of lobes 9.0–10.0 × 5.3–5.5 mm ; column 3.5 mm long, slender, terete, reflexed at apex, clinandrium/anther cap dorsal; anther, pollinarium, and fruit not seen. FIGURE 1. Macroclinium larense Carnevali & Cetzal. A. Habit with inflorescence. B. Inflorescence. C. Flower, lateral view. B. Sepals and petals and labellum. E. Labellum, front view. F. Column, lateral view. (based on Davidse & González 21237 , MO). Redrawn by W. Cetzal from a plate originally drafted by C. Yam. Distribution and ecology :— Macroclinium larense is only known from Yacambú National Park in Lara State , Venezuela , where it grows in cloud forests ( Fig. 2 ). This new species represents the first record of Macroclinium for western Venezuela , an area where more species of the genus are to be expected. Etymology :—The specific epithet of this species refers to the type locality, Lara State , Venezuela . Diagnostic features :—This new species is similar to Macroclinium borjaense from the Amazonian slopes of the Andes in Napo Department, Ecuador . Both are species occurring at relatively high elevations for the genus in cloud forests. Macroclinium larense differs from M. borjaense in its wider isthmus, which is about as long as broad, whereas it is conspicuously longer than wide in M. borjaense ; furthermore, the size and proportions of other floral organs are also different ( Table 1 ). These include shorter petals (4.0– 4.2 mm in M. larense vs. 11.0 mm in M. borjaense ), which are proportionally broader ( 0.30 W /L vs. 0.18 in M. borjaense ), much shorter labellum ( 5.9–6.1 mm long vs. 10.5 mm in M. borjaense ) and column (3.5 vs. 5.8 mm in M. borjaense ). In M. larense the claw of the labellum is proportionally longer, being as long as the isthmus, whereas this structure is proportionally shorter in M. borjaense . Macroclinium larense belongs in Macroclinium sect. Macroclinium subsect. Macroclinium ( sensu Pupulin 2001 ) on account of its caespitose habit, presence of pseudobulbs, articulate leaves, and subcapitate inflorescence. FIGURE 2. Distribution of Macroclinium larense versus M. borjaense and Venezuelan species. Key to the Venezuelan species of Macroclinium 1. Plants minute (< 1 cm tall without the inflorescences), pseudobulbs absent; leaves 5–8 mm long, not articulate with their sheaths; labellum elliptical and shortly unguiculate; plants from the lowlands of Amazonas and Bolivar state , Venezuela ..................................................................................................................................................................... 2 - Plants larger (> 2 cm tall without the inflorescences); pseudobulbs present; leaves 11–30 mm long, articulate with their sheaths; labellum conspicuously unguiculate; plants from Lara, Bolivar, Monagas , and Sucre states ............... 3 2. Leaves with smooth surface ......................................................................................................................... M. mirabile – Leaves with verruculose surface .......................................................................................................................... M. sp. 3. Leaves smooth; pedicel + ovary 4 mm long; labellum longer than column; column 3.5 mm long; only known from the Andean region in Lara State .................................................................................................................... M. larense - Leaves with a reticulate/rugulose surface; pedicel + ovary 7–12 mm long; labellum shorter than column; column 5– 6 mm long; plants from E and SE Venezuela in Amazonas , Bolivar , Monagas , and Sucre .... M. wullschlaegelianum