are creamy white. The fore feet are brown-furred and much shorter than the hind feet, which are in covered in part by a mixture of brown and cream hairs and in part by dark brown hairs. The fore and hind feet both have four digits, which end in small, curved claws, and three black pads. The palms and soles are naked. The tail is hairy with the hairs on the upper side are longer than those below. The upper side is gray-brown at the base, light to medium brown intermixed with cream in the middle, and reddish-brown at the tip, and the lower side is dark brown. In the single measured specimen, head and body length is , tail length is , hind foot length is , ear length is , and body mass is . The skull is long and compact. The premaxillary bones extend slightly in front of the upper incisors and the zygomatic arches (cheekbones) are broad. The suture between the premaxillary and frontal bones is more strongly curved than in L. peruanum and the rostrum (front part of the skull) is wider and the interorbital region is narrower than in L. viscacia and L. wolffsohni. The incisive foramina (openings in the front part of the palate) are long and narrow. The palate extends back to a point close to the upper third molar. The sides of the mesopterygoid fossa (the opening behind the back margin of the palate) are more strongly divergent than in other Lagidium species. The mandible is strong. The dental formula is (one incisor, one premolar, and three molars on each side of the upper and lower jaws). The incisors are large, white, and distinctly grooved. The molars are low-crowned and rootless (continuously growing). Ecology and conservation status L. ahuacaense is known only from Cerro El Ahuaca, a steep granite inselberg near Cariamanga in Loja Province, southern Ecuador, where it occurs at an altitude of , but only near rocky surfaces. The vegetation is dominated by the molasses grass (Melinis minutiflora). They eat plants, and traces of their feeding are visible on the mountain. Their habitat on Cerro El Ahuaca covers an area around , and the total population there may not contain more than a few dozen individuals. Except for some small outcrops close to the Cerro, no nearby habitat is suitable, but more populations may exist elsewhere in southern Ecuador or