Mice of the genus Mus in the Crimea: species diagnostics, distribution, and ecology

Abstract

The paper presents the first detailed summary of the current state of mice of the genus Mus in the Crimea, namely of the house mouse (Mus musculus Linnaeus, 1758) and steppe mouse (Mus spicilegus Petenyi, 1882). Morphological structures of the house mouse and steppe mouse are characterized and external and craniometrical features important for species diagnostics are presented. Most of the morphological characters tend to vary within the entire geographic range of both species. Body length of house mice is significantly greater compared to that of steppe mice. Tail length in house mice is greater than in steppe mice, but the tail index is greater in the latter. Therefore, house mice look more ‘short-tailed’, and this feature can be used as an additional diagnostic character. In steppe mice, the tail becomes thinner gradually from base to tip and thus it is awl-shaped. The tail of fit house mice, especially of autumn-winter generations, often has a thickened base, which increases the visual effect of a short tail. Among internal characters, the most significant are the differences between testicles size of mature males. For species diagnostics of mice of the genus Mus, the size and shape of the following cranial structures can be used: location of the root and frontal wall of the crown of the first upper molar (M1) in relation to the diastema; zygomatic process of the maxilla and zygomatic arch; palatine foramens foramina palatinum, and others. These are reliable characters for morphological identification of M. musculus and M. spicilegus in the territory of the Crimea, in the zone of their sympatry. Reliable diagnostic characters are the dimensions of palatine foramens. In general, the entire complex of characters analysed in this study should be used for correct morphological diagnostics of these species. Features of distribution and population dynamics of the house mouse and steppe mouse in the Crimea are studied. It has been revealed that both the house mouse and the steppe mouse are distributed mainly in the lowland part of the Crimea and the forest-steppe belt of the foothills. Data on the ecology of species are presented, including specifics of reproduction and habitat preferences. The place and role of house mice in small-mammal assemblages of various landscape and ecological zones are estimated.