A new species of Creagrutus is described from several localities in the upper Río Magdalena drainage, Colombia. Creagrutus dulima n. sp. differs from all trans-Andean congeners by the combination of a relatively small orbital diameter, the shape and position of hooks on the pelvic-fin rays, in having the third infraorbital not in contact with the preopercle ventrally, and the presence of a dark, reticulated pigmentation pattern on the dorsal portion of body. The distribution of Creagrutus species in the Magdalena-Cauca River Basin is discussed, and an updated identification key for species of trans-Andean Creagrutus is provided.