Pupulin, F. 2010. Flora Costaricensis. Family #39 Orchidaceae: Tribe Cymbidieae: Subtribe Zygopetalinae. Fieldiana, Bot. n.s. 49: i-iv, 1-60.

Introduction
This is the second volume of the series on Orchidaceae for Flora Costaricensis, after the fundamental contribution by Atwood and Mora de Retana, published 10 years ago. The present work was conceived and realized at Lankester Botanical Garden, University of Costa Rica (LBG), as part of the commitment by the center to carry out a complete inventory of the orchid flora of the country and to provide relevant information for the conservation of endangered taxa. In the past 10 years, the activities of botanical exploration carried out by the staff of LBG significantly improved the living plant collections grown at the Garden, revealed several floristic novelties, and made important steps toward a better understanding of species identity in this large and taxonomically complex group of plants. Perhaps more important, the activities of LBG focused on the retrieval of historic and critical taxonomic documentation, including original protologues and digital images of types, fundamental to interpretation of the diverse flora of Costa Rica. Several institutions have been particularly cooperative in this effort, among which the Harvard University Herbaria, the Herbarium of the Royal Botanic Gardens, Kew, the Herbarium of the Naturhistorisches Museum in Vienna, and the Herbarium of the Marie Selby Botanical Gardens must be mentioned for establishing formal agreements with the University of Costa Rica to allow the reproduction and use of the relevant material kept in their respective collections. The treatment of the orchid subtribe Zygopetalinae greatly benefited from the molecular work done at the Florida Museum of Natural History, University of Florida, and the generic concepts adopted in this volume are based on the phylogenies suggested by DNA analyses carried out there. These are reflected in the new classification formally proposed in Genera Orchidacearum (Pupulin, 2009b), and I hope that the nomenclature used in the present treatment will persist. Although they only represent a small portion (around four percent) of the Costa Rican orchid flora, species of Zygopetalinae are frequently grown (and often avidly collected) for horticultural purposes, and their study is crucial to understanding distribution patterns and species frequency as the first step to establish conservation priorities. Among the genera of Zygopetalinae, Dichaea constitutes a particularly common element in any type of vegetation in the country, and its taxonomic treatment should have a certain utility to field botanists working in Costa Rica. Sixteen genera (including a natural hybrid genus) and 60 species are treated. The work was based on direct examination of the available specimens deposited at AMES, CR, INB, K, M, SEL, USJ, and W; the spirit collection of Lankester Botanical Garden (JBL-Spirit); and scrutiny of digital images fromthe collections kept at F, NY, MO, and US. To ensure nomenclature stability, many of the Costa Rican taxa in the group were recently typified (Pupulin, 2001, 2007a), and additional lectotypes are selected here for Cryptarrhena guatemalensis Schltr. (AMES), Kefersteinia subquadrata Schltr. (AMES), and Warczewiczella caloglossa Schltr. (AMES). Many of the descriptions of individual species are based on those appearing in recent generic revisions by the author (Pupulin 2001, 2006a, 2006b, 2007a, 2009a); they include the observed variations among specimens native from Costa Rica. All the treated taxa are illustrated with one or more ink illustrations. With the exceptions of D. acostae Schltr., D. gracillima C.Schweinf., and D. gomez-lauritoi Pupulin, which are known only from the dried material of the type collections, the illustrations of all the remaining taxa were prepared by the author on the basis of living specimens with the aid of a stereomicroscope fitted with a drawing tube. As in the previous volume of this series on Costa Rican Orchidaceae, the illustrations are arranged according to their occurrence in the keys to facilitate the comparison of closely allied taxa.

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