Coming Soon to a Cellar Near You: Novel Range Expansion of a Short-Bodied Cellar Spider, Physocyclus enaulus (Araneae: Pholcidae), in a Building in Central Illinois, USA

A reproductive population of Physocyclus enaulus Crosby, 1926 (Pholcidae: Araneae), a short-bodied cellar spider native to the American southwest and Mexico, is documented for the first time in a single building in Illinois, far outside of their known native range. The means of introduction is unknown but is likely influenced by either accidental hitchhiking spiders or a deliberate introduction to control brown recluse populations. Cellar spiders were purchased and released in the same building to predate on brown recluse spiders, but the first P. enaulus individual was found a year prior to the release. These cellar spiders have a wide-ranging diet and eat both native and other introduced species, and P. enaulus may pose a threat to native ecosystems if they spread beyond their current location.