LANKESTERIANA 17(2): 153—164. 2017. doi: http://dx.doi.org/10.15517/lank.v17i2.29850 TWO NEW SPECIES OF PLEUROTHALLIS (ORCHIDACEAE: PLEUROTHALLIDINAE) FROM COSTA RICA IN THE P. PHYLLOCARDIA GROUP FRANCO PUPULIN1–3,5, MELISSA DÍAZ-MORALES1, MELANIA FERNÁNDEZ1,4 & JAIME AGUILAR1 1 Lankester Botanical Garden, University of Costa Rica. P.O. Box 302-7050 Cartago, Costa Rica 2 Harvard University Herbaria, 22 Divinity Avenue, Cambridge, Massachusetts 02138, U.S.A. 3 Marie Selby Botanical Gardens, 811 South Palm Avenue, Sarasota, Florida 34236, U.S.A. 4 Department of Plant & Soil Science, Texas Tech University, Lubbock, Texas 79409, U.S.A. 5 Author for correspondence:
[email protected] ABSTRACT. Two new species of Pleurothallis subsection Macrophyllae-Fasciculatae from Costa Rica are described and illustrated, and their relationships discussed. Pleurothallis pudica, from the central Pacific mountain region, is compared with P. phyllocardia, but it is easily recognized by the densely pubescent- hirsute flowers. Pleurothallis luna-crescens, from the Caribbean slope of the Talamanca chain, is compared with P. radula and P. rectipetala, from which it is distinguished by the dark purple flowers and the distinctly longer, dentate petals, respectively. A key to the species of the group in Costa Rica and western Panama is presented. KEY WORDS: flora of Costa Rica, new species, Pleurothallidinae,Pleurothallis phyllocardia group Introduction. The species of Pleurothallis R.Br. can be distinguished. Even excluding the group that close to Humboltia cordata Ruiz & Pavón (1978) [= Wilson and collaborators (2011, 2013) characterized as Pleurothallis cordata (Ruiz & Pav.) Lindl.] represent the “Mesoamerican clade” of Pleurothallis, consisting one of the largest groups of taxa within the genus (Luer of fairly small plants and mostly non-resupinate flowers 2005).