The primary hosts of this flea are mustelids, but it is frequently found infesting a variety of small mammals. It is a species of the Arctic and Subarctic in Canada. Lewis and Eckerlin (Annals of the Carnegie Museum 81: 119-134 (2013)) elevated the subgenus, Rosickyiana Smit, to full generic status, and in the process, synonymized two previously known subspecies (as cited in Holland 1985), Ceratophyllus (Rosickyiana) lunatus lunatus (Jordan and Rothschild) and C. (R.) lunatus tundrensis Holland. Records are widely spread across the north, including AK and Greenland. The small number of occurrences is likely a reflection of insufficient collecting effort rather than indicative of its true abundance. More data are needed before an accurate rank can be assigned to this species of flea.