Microcebus mamiratra is similar to M. sambiranensis except that it is slightly larger, with a a head-body length of about 12.7 cm, a tail length of about 14.3 cm, a total length of 27 cm, and a body weight of 50–60 g (Andriantompohavana et al., 2006). The fur is dense and short, with the upper body and head (including the ears) being a light reddish- brown (becoming a brighter reddish-brown on the dorsum and crown cap), and white to creamy below. There is sometimes a faint, light grayish-brown dorsal line. The tail changes gradually from rufous-brown on the proximal part to dark brown at the tip. The hands and feet, though poorly-haired, are gray or white. A whitish midline stripe is found on the anterior part of the muzzle, which is wider and more diffuse between the eyes (Andriantompohavana et al., 2006).
Shortly after the description of this species, Olivieri et al. (2007a) described the same animal, giving it the name lokobensis. However, since this name was published after the name M. mamiratra, it becomes a junior synonym.