This dataset is associated with the published paper Escalante, I, M Domínguez, D Gómez-Ruiz, and G Machado. Benefits and costs of multi-specific aggregations in harvestmen (Arachnida: Opiliones). Frontiers in Ecology and Evolution (DOI 10.3389/fevo.2021.766323). Please refer to the paper for the extensive explanations on the collection, analysis, presentation, and analyses of the data. We provide the first description of mixed-species roosting aggregations of seven species of the genus Prionostemma from Costa Rica. We surveyed several...