COMPARATIVE MORPHOMETRY AND CYTOGENETICS OF MICROTUS (TERRICOLA) MULTIPLEX (ARVICOLIDAE, RODENTIA) OF THE WESTERN FRENCH ALPS

The western French Alpine populations of Microtus (Terricola) multiple x (Arvicolidae, Rodentia) occupy the marginal distributional area of t he species. Analysis of the characters of the Relative Length of the A nterior Part (RLAP) and of the Pitymyan Rhombus (PR) of the first lowe r molar (M1) of these populations and subsequent comparison with other populations from the Central Alps of France and Switzerland permits t o distinguish the populations of the western French Alpine area (Saint -Martin-de-la-Cluze and La-Chapelle-en-Vercors) from the populations o f the Central Alps belonging to the subspecies multiplex, fatioi and d ruentius. Karyological analysis of the population from Saint-Martin-de -la-Cluze confirms the cytogenetic differentiation of populations from the western French Alpine area which arc characterized by a subteloce ntric X chromosome and a metacentric Y chromosome. The synthesis of th ese results leads to the proposal of a new subspecies for the populati ons from the western French Alpine area, Microtus (Terricola) multiple x niethammeri nov. ssp.