Microryzomys altissimus

Material captured. Four females and 19 males (QCAZ 17907–17919), measurements (in mm): total 174–202, ear 13–17, foot 19–25; 03°03′43″S, 079°13′54″W; 3,860 – 3,760 m; 26, 31 July; 2–5, 7 August 2018; collectors: Lee, Tinoco and Crockett. These specimens were collected in herbaceous paramo stream and patch forest in Sherman traps.

Identification. These specimens are brownish dorsally with a grayish grizzled head (Fig. 2E). The tail is bicolored and less than 142 percent of head and body length, that is indicative of M. altissimus (Carleton and Musser 1989). The hands and feet are whitish. The incisor tubercle on the dentary is short and indistinct and the length of maxillary toothrow is greater than 3 mm. The incisive foramina are long, penetrating M1 (Carleton 2015). Microryzomys minutus has a unicolored tail greater than 145 percent of head and body length. The incisor tubercle on the dentary is distinct and large, the length of maxillary toothrow is less than 3 mm, and the incisive foramina do not penetrate M1.