The Mindanao montane forest mouse occurs on Mindanao and Dinagat, in forests from sea level to 2,800 m.
Compared with its close relative A. hylocoetes, A. insignis is described as having a longer tail, longer and narrower hind feet, and a shorter rostrum.
In standardized captures on the Kitanglad Range, all 58 records with a known time were nocturnal or crepuscular, with none during daylight. Stomach contents from 35 animals included vegetable matter in 91% and arthropod exoskeleton in 97%.
An extinction-risk assessment has not been added yet.