Exploring Costa Rica's fungal trends: Insights from digitized specimens

Societal Impact Statement Fungi are essential to tropical ecosystems but remain largely absent from conservation agendas. By analyzing over 78,000 fungal records from Costa Rica—a globally recognized biodiversity hotspot—this study reveals key patterns in fungal diversity, distribution, and seasonality. These insights support more inclusive conservation strategies, ecological monitoring, and biodiversity policy. The study also reinforces the vital role of biological collections such as fungaria, while highlighting the urgent need for more fungal inventory work in tropical regions, supported by sustained funding. In Costa Rica, understanding fungal diversity can foster ecotourism, create local jobs, and enrich community knowledge. Summary This study examines fungal diversity in Costa Rica, a Neotropical biodiversity hotspot. Using over 78,000 records from national and international fungaria and culture collections, we explore diversity patterns, geographic distributions, and phenology to better understand the Costa Rican fungi. Our collections dataset, primarily from fungaria (99.8%) and spanning 170 years, includes all major fungal groups, with most specimens identified to genus level. It increases the number of currently known Costa Rican fungi from 5676 to 6789 species. We estimated species diversity using collections and non‐collections‐based methods and carried out spatial, temporal, and phenological analyses to look at patterns of fungal collection, distribution, and phenology in relation to ecology and climate. Rarefaction and species richness estimators using the 2862 recorded species in our collections dataset gave an expected total fungal species diversity of 4155 species, fewer than currently known. When using non‐collection‐based estimations, expected species diversity ranged from 6911 to 40,373, meaning the collections could represent as much as 41.4% or as little as 7.1% of the total species diversity in Costa Rica. Species richness was highest in lower montane wet, tropical wet, and premontane pluvial forests, and sporocarp production peaked in the rainy season with distinct phenological patterns. Despite inherent biases and uneven sampling, Costa Rica's fungal collections provide a critical historical and ecological baseline, revealing meaningful patterns in fungal diversity, distribution, ecology, and phenology. Improving data quality requires consistent curation, standardized locality information, and broader sampling guidelines. Establishing a national microbial culture collection would further support long‐term preservation and access.