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The first checklist of the odonates from Guyana is presented, including 46 new species records. Literature sources are provided for all species and for the new records full locality data, color scans or field photographs, taxonomic and biological notes, and maps for those species whose distribution range is increased considerably.

Extreme climatic events such as the El Niño Southern Oscillation profoundly affect many plants and animals, including amphibians, which are strongly negatively affected by drought conditions. How amphibians respond to exceptionally high precipitation as observed in La Niña events, however, remains unclear. We document the correlation between the exceedingly wet 2010–2012 La Niña and community‐level changes in a leaf litter frog assemblage in Costa Rica. Relative abundances of species shifted, diversity and plot occupancy decreased, and community composition became homogenized with the onset of La Niña. These aspects remained altered for over 20 months but rebounded to pre‐La Niña levels after approximately 12 months. We hypothesize that complex ecological cascades associated with excess moisture caused short‐term declines in abundances of species and associated changes in community structure. If additional stressors such as disease or habitat loss are not co‐occurring, frog communities can rapidly recover to pre‐disturbance levels following severe climatic events.

Roughly 40% of amphibian species are in decline with habitat loss, disease, and climate change being the most cited threats. Heterogeneity of extrinsic (e.g. climate) and intrinsic (e.g. local adaptations) factors across a species' range should influence population response to climate change and other threats. Here we examine relative detectability changes for five direct-developing leaf litter frogs between 42-year sampling periods at one Lowland Tropical Forest site (51 m.a.s.l.) and one Premontane Wet Forest site (1100 m.a.s.l.) in southwest Costa Rica. We identify individualistic changes in relative detectability among populations between sampling periods at different elevations. Both common and rare species showed site-specific declines, and no species exhibited significant declines at both sites. Detection changes are correlated with changes in temperature, dry season rainfall, and leaf litter depth since 1969. Our study species share Least Concern conservation status, life history traits, and close phylogenetic relationship, yet their populations changed individualistically both within and among species. These results counter current views of the uniformity or predictability of amphibian decline response and suggest additional complexity for conservation decisions.