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Background: Mesoamerica is one of the most important biodiversity hotspots on the planet. Despite significant efforts made over two centuries to contribute to the floristic knowledge of this region, our understanding of its flora is still scattered and uneven. Questions: What is the magnitude of the vascular plant species richness in the Usumacinta River Basin? Study site and dates: Usumacinta River Basin (Guatemala and Mexico), 1838-2018. Methods: We compiled the checklist by systematizing the floristic information acquired from various sources derived from numerous floristic and ecological studies. Results: We recorded 6,977 species, 1,892 genera and 274 families. The largest numbers of species (5,746) and records (58,859) correspond to the Mexican portion of the Usumacinta River Basin, compared to its Guatemalan counterpart (4,445 species and 19,952 records). The most species-rich families were Orchidaceae (598 species), Fabaceae (512), and Asteraceae (476). The prevalence of these and all other families with significant contributions to the flora varied among three elevation-defined sectors into which the Usumacinta River Basin was subdivided (lower, middle, and upper basin). Conclusions: The Usumacinta River Basin is a strategic region for plant biodiversity conservation as it hosts almost one third of all vascular plant species known for Mesoamerica and ca. 6 % of the entire flora in the Americas. Further botanical exploration should focus on those areas of the basin for which little or no information is available in order to gain a better appreciation of its flora.

Background and aims – In the tropics, some studies have found that the richness of epiphytic ferns present a peak at mountain mid-elevations. However, it is not well understood how transitions from tropical to subtropical conditions affect this peak, and even less is known about beta diversity of epiphytic ferns. Thus, the objective is to understand the effect of climatic gradients on the variation of local richness of ferns and beta diversity patterns along an elevational gradient in a mountain system in southern Mexico.Methods – We sampled 32 trees, each in four elevational bands (100–2200 m). Alpha diversity patterns were analysed using linear regression models. We used the Morisita index to quantify species turnover between bands. An additive partitioning approach was used to analyse the degree to which individual trees, plots, and bands contributed to total species richness. We evaluated the influence of climatic variables on species composition via linear regression models.Key results – A total of 30 species in five families were recorded. Each family contributed in different magnitude to the elevational richness pattern, with Polypodiaceae dominating due to its richness and presence along the entire transect. Alpha diversity at the three scales (αtree, αplot, αband) increased with elevation and rainfall, and with decreasing temperature. Species turnover was high along the gradient, but was scale-dependent, with βtransect (65–75%) and βband (14%) with the greatest contributing to total diversity. Although the contribution of the individual trees was lower, it increased with elevation. Conclusions – We emphasize the importance of including different scale levels in analyses of diversity along elevational gradients. In the region, cloud forest on the mountain peaks harbours the highest diversity of epiphytic fern communities. Due to a limited extent of this mountain range, the epiphyte ferns are susceptible to the effects of climate change.

Este estudio exploró la influencia de las estrategias de afrontamiento en el bienestar psicológico de estudiantes universitarios dominicanos durante la pandemia del COVID-19. Participaron 135 estudiantes de una universidad privada, entre 18 y 25 años, completando una encuesta virtual con la Escala de Bienestar Psicológico (EBP) y la escala de Orientación hacia el Afrontamiento de Problemas Experimentados (COPE-48). Seis regresiones múltiples con selección forward crearon modelos de predicción de cada dimensión del bienestar psicológico con las estrategias de afrontamiento como variables independientes. Los modelos explicaron del 23 % al 40 % de la varianza del bienestar psicológico. Un análisis factorial clasificó las estrategias de afrontamiento en: (1) positivas, ejerciendo una influencia positiva en el bienestar; y (2) negativas, ejerciendo una influencia negativa en el bienestar. Las estrategias positivas significativas fueron: (1) aceptación y crecimiento personal, y (2) búsqueda de apoyo social. Las estrategias negativas significativas fueron: (1) consumo de alcohol o drogas, (2) centrarse en las emociones y desahogarse, (3) negación, y (4) refrenar el afrontamiento. Las medidas de distanciamiento y la desconfianza en autoridades de salud durante la pandemia dificultan usar estrategias de afrontamiento positivas, favoreciendo el uso de estrategias negativas. Esto aumenta el riesgo de desarrollar sintomatologías clínicamente relevantes.

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Background: Some regions of Mexico have been relatively well explored floristically and estimates of the vascular plant richness they contain have been obtained. However, there are still regions that require effort to obtain the most appropriate lists of flora possible that consider both systemization of the information and that benefit from recent botanical explorations. Questions: What is the species richness of vascular plants in the Tacaná-Boquerón Priority Terrestrial Region? What proportion of the species are endemic or included in risk categories? Study sites and dates: Tacaná-Boquerón Priority Terrestrial Region, Chiapas State, Mexico. This region is on the Guatemala border and covers an area of 57,400 ha. Between 1920 and 2015. Methods: A database of 14,487 vascular plant records was integrated. Two sources of information were compared: systematization of databases, and recent botanic expeditions. Results: We found 2,485 native species belonging to 185 families. Both data sources were complementary in order to obtain a more complete floristic checklist (systematization of database: 1,774 spp., recent botanic expeditions: 1,514 spp.). As novelties, we found three new species and seven new reports for Mexico. Approximately 14 % of the species documented are included in risk categories or are endemic to the study site. Conclusions: Our checklist is one of the largest in the region (Mexico and Central America) in terms of species count. Our study shows the importance of conducting botanical explorations to complement the information on vascular plant richness in relatively well-explored areas of Mexico.