We discuss a group of Pleurothallis species mostly characterized by plants relatively tall for the genus, with stems more than 20 cm long and fasciculate inflorescences produced above the leaf from a spathaceous, sometimes erect bract. We recognize 26 species and 4 natural hybrids in Costa Rica in this group of Pleurothallis, belonging to 4 informal assemblages of species, each one characterized by a unique set of vegetative, floral, and ecological features. This group, as well as its component units, is discussed as to its salient characteristics and internal relationships, underlying possible evolutionary trends. Diversity, general and floral ecology, color dimorphism, and natural hybridization are examined to address their systematic significance. We present a dichotomic key to the groups and the species discussed in this study, together with descriptions based on Costa Rican materials, and one or more line drawings or a Lankester Composite Dissection Plate when required for improved clarity. Also, we discuss their taxonomy and provide information on etymology, habitat, distribution, distinguishing features, and Costa Rican collections. Three species (P. callosa, P. longipetala, and P. mesopotamica), and three nothospecies (P. ×karremansiana, P. ×subversa, and P. ×parentis-certa) are described as new to science, discussed as to their affinities, and illustrated with photographs, composite digital plates, and ink drawings. Pleurothallis triangulabia is removed from the synonymy of P. phyllocardia, treated as a distinct species, and lectotypified. Pleurothallis anthurioides and P. maduroi are first recorded and documented for the flora of Costa Rica.

This study presents an updated comprehensive catalogue of the Costa Rican orchid flora. We have documented 1684 species, four subspecies, 14 natural hybrids, and seven forms across 201 genera and two nothogenera, × Bensteinia and × Cochlezella. All Orchidaceae subfamilies are represented except for Apostasioideae. The subtribe Pleurothallidinae accounts for about 35% of all the species, followed by Laeliinae (20%) and Oncidiinae (+12%). The most species-rich genera in Costa Rica are Epidendrum (245 spp.), Lepanthes (163 spp.), Stelis (109 spp.), and Pleurothallis (63 spp.). About 30% of all the species are endemic, primarily concentrated in Lepanthes (109 spp. = 67%), Epidendrum (76 spp. = 31%), Stelis (40 spp. = 37%), Telipogon (35 spp. = 88%), and Pleurothallis (31 spp. = 46%). All species are vouchered by specimens housed in major public herbaria, including CR, JBL, and USJ in Costa Rica, as well as AMES, K, SEL, US, and W, on the international scale, among others. The catalogue includes 5300 orchid names at the specific and subspecific ranks, nearly 70% of which are treated as synonyms. The new catalog presents an increase of 324 species compared to its predecessor, published twenty years ago, a net increment of almost 24%. The rise in the recorded richness of the Costa Rican orchid flora is mainly attributed to the discovery of species new to science and a lesser extent, taxa newly recorded for the country as the result of the systematic explorations carried out in Costa Rica during the present century. A phylogenetic arrangement of the genera recorded in Costa Rica, from the rank of subfamily to that of subtribe, is presented, including a synopsis of the diversity recorded for each genus. An enumerated checklist of the accepted species and a comprehensive index of accepted names and synonyms are also provided. The index is cross-referenced with both the checklist and the main catalogue. New combinations for Andreettaea fimbriata and Camaridium muscoides are proposed. Photographs of representative species from the majority of genera, based on Costa Rican vouchers, are included. We expect that this catalogue will inspire orchidological and botanical research in Costa Rica and other Neotropical regions, leading to additional discoveries in the upcoming years

A new nothospecies in the subtribe Zygopetalinae (Orchidaceae), × Cochlezella costaricensis, representing a cross between Cochleanthes aromatica and Warczewiczella discolor, is described and illustrated from Costa Rica, and its relationships are discussed.

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.

This paper focuses on the systematics of the Specklinia endotrachys species complex in Costa Rica. Traditionally considered a variable species, S. endotrachys is here treated as one of at least four, albeit closely related, taxa. Of these species, S. endotrachys, S. pfavii, and S. spectabilis are described and illustrated from living material, and S. remotiflora is described and illustrated as new to science. Specklinia remotiflora is compared with S. endotrachys and S. spectabilis, from which it differs in the repent habit, lax inflorescence and campanulate flowers provided with convergent sepals and non-apiculate petals. New combinations are proposed for Pleurothallis pfavii and P. spectabilis. A lectotype is selected for Pleurothallis endotrachys. Observations on the pollination of S. remotiflora and S. spectabilis in cultivation are given.

Natural hybridization in Neotropical orchids is summarized, and the frequency of nothogenera in the subtribe Zygopetalinae is highlighted. A new nothogenus discovered in Costa Rica, formed by the cross between species of Benzingia and Chondroscaphe , is described, and the new nothospecies × Benzoscaphe stelleri is described and illustrated. Putative parents, as well as their derivative hybrid, are compared through composite digital plates. Cues are offered about the pollination mechanisms of the putative parents, based on the morphology of the flowers and pollinaria, which possibly led to the formation of the natural cross between different genera.