From WordNet (r) 2.0 (August 2003) [wn]:
Arvicola
n : in some classifications considered synonymous with Microtus
[syn: Arvicola, genus Arvicola]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Arvicola \Arvicola\ n.
a genus of mice in some classifications considered synonymous
with {Microtus}.
Syn: genus Arvicola.
[WordNet 1.5]