Taxonomic re-examination of the Apodemus agrarius chejuensis, comparing external and cranial morphological characters among four Asian Apodemus species

In order to re-examine the taxonomic position of the Korean striped field mouse, Apodemus agrarius chejuensis from the Cheju Island, external value and skull characters were compared among A. agrarius coreae from the Korean Peninsula, A. speciosus, A. argenteus, and A. semotus. Skull characters of A. agrarius chejuensis (Cheju population) and A. agrarius coreae (mainland population) were fitted onto different clines. In paticular, distances between the posterior end of incisive foramina and anterior end of the first upper molar were critically different between these two subspecies. These evidences support the specific division of 'Apodemus chejuensis' for the population inhabiting the Cheju Island from A. agrarius in the mainland, as proposed by Koh and Yoo(1992).