A new species of blister beetle (Coleoptera, Meloidae, Mylabrini), Croscherichia armass Ruiz, François & García-París, sp. nov., is described from the arid steppes of eastern Morocco (Missour, Boulemane Province). The new species presents traits shared with both Croscherichia and desert species of the genus Ammabris, making it morphologically singular. Conspicuous external similarities (coloration pattern, shape of the mandibles, setation) between C. armasssp. nov. and Ammabris allow the two to be easily confused. However, C. armasssp. nov. can be readily distinguished from all other Croscherichia species by the following traits: reddish-orange legs with dark tarsi; relatively short black antennae with the proximal-most three to four antennomeres of each antenna having a reddish-brown coloration; dense and silvery body setation that lies over most of the body integument; straight and pointed outer mandible margins that protrude from the labrum; a mesosternum with an angulate anterior margin; a short, subcylindrical, and weakly spatulate external metatibial spur that is truncated obliquely at the apex. Croscherichia armasssp. nov. is only known from three localities in the arid Hammada steppes, which are located within the Quaternary alluvial plains of the Muluya river valley. Live specimens of C. armasssp. nov. were found in flight and actively feeding on Atriplex halimus (Chenopodiaceae) flowers at the end of summer (mid-September). The phenology of C. armasssp. nov. is exceptional as no other Mylabrini species known from eastern areas of Morocco are active in late summer.