Measuring What We Don't Know: Biodiversity Catalogs Reveal Bias in Taxonomic Effort

Biodiversity catalogs are an invaluable resource for biological research. Efforts to scientifically document biodiversity have not been evenly applied, either because of charisma or because of ease of study. Spiders are among the most precisely cataloged and diverse invertebrates, having surpassed 50,000 described species globally. The World Spider Catalog presents a unique opportunity to assess the disproportionate documentation of spider diversity. In the present article, we develop a taxonomic ratio relating new species descriptions to other taxonomic activity as a proxy for taxonomic effort, using spiders as a case study. We use this taxonomic effort metric to examine biases along multiple axes: phylogeny, zoogeography, and socioeconomics. We also use this metric to estimate the number of species that remain to be described. This work informs arachnologists in identifying high-priority taxa and regions for species discovery and highlights the benefits of maintaining open-access taxonomic databases-a necessary step in overcoming bias and documenting the world's biodiversity.