The Cairo spiny mouse Acomys cahirinus shows a strong affinity to the Mongolian gerbil Meriones unguiculatus.

The classification of the African spiny mice (genus Acomys) within the Muridae family of rodents has been fraught with controversy. Morphological data suggest a close affinity between this group and true old world mice of the genus Mus. However, the combined results of immunological, biochemical, and DNA melting studies suggest that spiny mice should not even be considered as members of the Murinae subfamily. To further elucidate the position of the spiny mice within the rodent phylogenetic tree, we performed a direct sequence comparison of a 583-nucleotide homologous region from the spiny mouse type species Acomys cahirinus and five other representative rodent species. Our results provide incontrovertible evidence to support the contention that the spiny mouse is more closely related to the Mongolian gerbil Meriones unguiculatus than it is to Mus musculus.