California is considered one of the top twenty-five global biodiversity hotspots, and has more native plant and animal species than any other comparable area in North America. In particular, there are several diverse arachnid lineages endemic to California. The genus Pimus Chamberlin, a cribellate amaurobiid, occurs almost exclusively in California. This study includes three interrelated primary OBJECTIVES: 1) Re-evaluate species hypotheses using a combination of multi-locus DNA sequence data and morphology, 2) Use DNA sequence data (primarily) to understand how Pimus species are interrelated (i.e., reconstruct species relationships), and 3) Use a combination of phylogenetic data and ecological niche data to understand the biogeographic history of Pimus. The combination of taxonomic, systematic, and historical biogeographic information will provide a comprehensive look at this interesting and diverse spider genus.