Geometric morphometric analysis of Iranian wood mice of the genus Apodemus (Rodentia, Muridae)

Morphological differences among five populations of Iranian wood mice belonging to three species of the genus Apodemus (A. witherbyi, A. hyrcanicus, and A. avicennicus) were investigated using landmark-based geometric morphometrics of the upper molars and the mandible. Results indicate that all species are completely recognizable by their shape. Apodemus hyrcanicus is the most distinct species, having short coronoid and angular processes. The upper molars of A. avicennicus are more similar to those of A. hyrcanicus, although the former is completely recognizable by the smaller size of the upper molars. This similarity, which relates to broadening and robustness of the upper molars, implies that these two species are more primitive than A. witherbyi. It seems that this primitive character has been retained in A. avicennicus after its separation from an ancestral population in the Zagros Mountains. There is no significant upper molar size difference between A. witherbyi and A. hyrcanicus. Mandible size is also statistically identical in the populations studied. Wood mice of northeastern Iran are morphometrically very close to A. witherbyi of the Elburz Mountains and are assumed to be the same species.