Microtus brachucercus was initially described by Lehmann in 1961 as a subspecies of
M. savii, under the name
Pitymys savii brachycercus.
brachycercus refers to its short tail. Genetic tests in the
Calabrian region found, although similar, the
X chromosome is larger than that of samples of
M. savii found elsewhere in Italy and the
Y chromosome is twice the size, leading Galleni in 1994 to designate
M. brachycercus as a separate species. DNA evidence suggests that
M. brachycercus separated from
M. savii 0.3 to 0.5 million years ago. The two species can
hybridize, but the male offspring are infertile and do not produce and
sperm. The females are fully fertile, however.
M. brachycercus has two subspecies,
M. brachycercus niethammericus and
M. brachycercus brachycercus. == Description ==