A widespread problem: cryptic diversity in the Libyan jird

Background The Libyan jird, Meriones libycus , is described as occurring from Morocco to the Mongolian plateau. Three subspecies are known from morphological determinations but not genetic data. We used museum collection locations to create a niche model of the most likely suitable habitat for this species within its potential extent. Using samples collected from the Kingdom of Saudi Arabia, we examined genetic diversity including available samples from China and Tunisia, providing the first genetic overview of this species. Results Mitochondrial cytochrome b data showed that genetic differentiation between Arabian and other sampling locations of M. libycus is less than the lineage separation seen in Meriones meridianus and greater than that in Meriones tamariscinus . The Arabian lineage investigated here is clearly distinct from the Chinese Meriones libycus erythrourus and Tunisian Meriones libycus syrius, the latter subspecies being previously suggested to occur in the sampling area. Conclusions We suggest further investigation to ascertain whether the lineage represented here is Arabian Meriones libycus arimalius or a different lineage entirely. We further question the reliability of previous morphological descriptions for producing specific determinations in Meriones and related taxa.