A new species of cicinnine Mimallonidae , Cicinnus chambersi sp. nov., is described from the Sky Islands Region of southern Arizona, USA. The new species is closely related to C. mexicana (Druce), type locality Veracruz, Mexico, based on morphology and genetics. The other Cicinnus species known from the United States, the common C. melsheimeri (type locality Pennsylvania, USA) is morphologically and genetically distinct from both C. chambersi and C. mexicana . The new species is compared to C. mexicana and C. melsheimeri , as well as other Mexican Cicinnus . The life history of C. chambersi is unknown, but its description should facilitate future studies on this rarely reported North American mimallonid, a species which may have only recently become established in the United States. Cicinnus chambersi is the fifth known Mimallonidae species from the United States, and the first described from the country in nearly half a century.