Two New Species of Pleurothallis (Orchidaceae) from the Amazonian Lowlands Carlyle A. Luer Research Associate of the Missouri Botanical Garden, P.0. Box 299, St. Louis, Missouri 63166-0299, U.S.A. Mailing address: 3222 Old Oak Drive, Sarasota, Florida 34239, U.S.A. German Carnevali Jardin Botanico de Caracas, Herbario Nacional de Venezuela (VEN), INPARQUES, Aptdo. 2156, Caracas 1010- A, Venezuela. Current address: Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri 63166-0299, U.S.A. and Department of Biology, University of Missouri-St. Louis, 8001 Natural Bridge Road, St. Louis, Missouri 63121, U.S.A. Abstract. Pleurothallis discophylla and P. er- ythrogrammaaredescribedandillustrated. These newspeciesaredistributedintheAmazonianlow¬ lands of Venezuela, Ecuador, Peru, and Bolivia. Pleurothallisdiscophyllahasbeenpreviouslymis- identifiedintheliteratureastheBolivianPleuroth¬ alliscoffeicola,whichisalmostcertainlyasynonym ofthewidespreadP.casapensis. The two following undescribed species are locally common and widespread in the western Amazon Basin. Both species are closely related and are char¬ acterized by a shortly creeping rhizome, sharply 3 -winged ramicauls, broadly elliptic to suborbicular, spreading leaves, and yellow or orange flowers pro¬ duced singly on short peduncles. Herbariumspeci¬ mens of these plants have been frequently misiden- tified as Pleurothallis coffeicola Schlechter, a species describedfromBoliviathatisalmostcertainlycon- specific with the frequent Andean species Pleuroth¬ allis casapensis Bindley. Pleurothallis discophylla Luer & Carnevali, sp. nov. TYPE: Ecuador. Morona-Santiago: epi¬ phytic in tall forest along Rio Upano N of Macas, 1,100 m, 15 Jan. 1989, C. Luer , J. Luer, P. & A. Jesup, A. Hirtz & S. Ortega 13927 (holotype, MO). Figure 1. Species haec P. casapensidis Lindley affinis, sed foliis suborbicularis, pedunculis unifloris et labello pyriforrni supra medium orbiculari tenui laevi differt. Plant medium to large in size, epiphytic, shortly creeping,therhizomestout,0.5-3cmlongbetween ramicauls; roots slender. Ramicauls erect, 6-12 cmlong, sharply3-winged, slightlybroadertoward the leaf, with 2-3 thin, tubular sheaths at the base. Leaf spreading, coriaceous, broadly elliptical to su¬ borbicular, obtuse, 4-7 cm long, 3-5 cm wide, sessile with the base ± cordate. Inflorescence a fascicle of peduncles, successively single-dowered, borne on top of the leaf, subtended by a spathe 5- 7 mmlong, fromthe apex of the ramicaul; peduncles 5 mm long; floral bract 3 mm long; pedicel 3 mm long; ovarycellular-glandular, 2.5mmlong. Sepals yellow to orange, brownish yellow or sometimes to¬ tallymaroon,glabrous,thedorsalsepallinear-ob- ovate,obtuse,thickenedandsubverrucosewithin toward the apex, 10-11.5 mm long, 3 mm wide, 3-veined, connate to the lateral sepals for 0.5 mm, the lateral sepals connate into an elliptical, bifid synsepal 9-10 mm long, 7 mm wide, 6-veined, the apex shallowly bifid with the tips acute and apiculate; petalstranslucentoryellowwithapurplemidvein, elliptical-obovate, obtuse, minutely serrulate, 3 mm long, 1.5 mm wide, with the vein thickened exter¬ nally, ending in a minute apiculum; lip yellow to orange or purple-brown with brownish yellow mar¬ gin, obovate-pyriform in outline, 5 mm long, 3.5 mm wide, the apex broadly rounded, entire, thin, smooth, the margins above the base erect, rounded, the disk minutely spiculate near the middle, with a pair of parallel, subverrucose calli on the middle third, the base thickened, truncate, hinged to the tipofthecolumn-foot;columnsemiterete,winged above the middle, 3 mm long, minutely toothed at theapex,thefoot2mmlong,theanther,rostellum, and stigma ventral. Etymology. From the Greek discophyllos, “round-leaved,”referringtothebroad,flatleaves. This species is closely related to the frequent Pleurothallis casapensis, but P. discophylla is found in warm forests at altitudes below 1,200 m. It is distinguished by the creeping rhizome, erect, sharply triquetrous ramicauls; spreading suborbicular leaves; Novon 3: 158-162. 1993.