 In the skull , the front part ( rostrum ) is large , but not as long as in A. budini . The skull is more robust than in the very similar Akodon boliviensis , but less so than in A. simulator . The hourglass @-@ shaped interorbital region ( between the eyes ) is narrower than in A. caenosus and not as squared as in A. polopi . Members of the Akodon varius group , with which Akodon oenos was formerly associated , tend to have much broader interorbital regions . The braincase is somewhat inflated and bears well @-@ developed temporal and lambdoid crests relative to the situation in A. caenosus ; Akodon polopi , however , has even better developed crests . 
