The Tacaná-Boquerón region (TBR) in Chiapas is considered an area of high biodiversity in Mexico, with a rich but poorly studied orchid flora, which is an important component of the vegetation and threatened by an accelerated rate of deforestation. By means of fieldwork, and the revision of scientific collections and literature, an orchid checklist for the TBR and adjacent areas was made; using geographic information systems the distribution of this orchid flora was analyzed in the study area. From 1,235 records we report 105 genera and 325 species, two of them determined to infraspecific level and two are natural hybrids; nine species were additions to the Mexican flora; 39 species are considered at risk in Mexico; the national distribution of a further 20 species are restricted to the TBR. This orchid flora represents 24 % and 44 % of the national and state orchid species richness, respectively, is the second richest in Mexico, and only surpassed by the region El Momón-Las Margaritas-Montebello (Chiapas). The greatest orchid richness is concentrated between elevations of 500 to 2,499 m, in areas now given over to permanent agriculture (including coffee and cocoa plantations); in primary forest the richness is lower. The Tacaná Volcano Biosphere Reserve is the only protected area in the TBR and the proposal to extend it to the Boquerón peak would promote the protection of the orchid flora growing above 1,000 m in the region. Traditional coffee plantations could be alternative to conserve orchids that grow below 1,600 m.

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Cyrtopodium valebellae, a new species from northwestern Argentina and southwestern Bolivia, is described, illustrated, and compared with morphologically similar taxa. The species is similar to C. virescens in general morphology and flower colour but differs in floral morphology details, particularly in lip morphology and geographic distribution. All known records are from the Southern Andean Yungas and Chaco Serrano ecoregions, indicating that the species is endemic to these regions. Cyrtopodium valebellae has been known since 1965 but has been misidentified so far with C. paniculatum, C. punctatum or C. virescens. The new species was first noticed through photographs available on online biodiversity platforms, highlighting its usefulness as a complementary source of data for discovering new species.

Habenaria longissima, a new species from the H. nuda species complex, is described and illustrated. It is remarkable for the exceptionally long lateral segments of the petals and labellum, which are the longest among Neotropical Habenaria, both in absolute and inproportional terms. Despite the morphological similarity, Bayesian and parsimony phylogenetic analyses based on nuclear (ITS) and plastid DNA markers (matK), revealed that H. longissima is distantly related to other species of the complex, and constitutes an independent lineage. Its distribution is unusual in that it is the only species of Orchidaceae restricted to the Quadrilátero Ferrífero in the State of Minas Gerais and to Chapada Diamantina, in the central part of the Espinhaço range in the State of Bahia, with the populations 1000 km from each other. Habenaria longissima is a rare species, known only from three localities and four populations and informally proposed as Endangered due to the small area of occupancy and small number of known populations.