Incan shrew opossum, Peruvian caenolestid
The Incan caenolestid (Lestoros inca ), also known as the Incan shrew opossum or Peruvian caenolestid, is a caenolestid found in the southern Peruvian Andes. It was first described by English zoologist Oldfield Thomas in 1917. The head-and-body length ranges from 9 to 11.5 centimetres (3.5 to 4.5 in), and the weight is between 25 and 32 grams (0.88 and 1.13 oz). It is brown on the back, and lighter on the underside. Little is known about the behaviour of the Incan caenolestid; it appears to be terrestrial and nocturnal. It feeds on small invertebrates and insects. This caenolestid inhabits elfin and secondary forests. The IUCN classifies it as least concern.
The Incan caenolestid, like the common shrew opossums, is characterized by a long snout and small eyes. A 2013 study gave a detailed analysis of the morphology of this shrew opossum. The Incan caenolestid appeared to be closer to Caenolestes than to the long-nosed caenolestid in morphology. Sexual dimorphism was not prominent. External measurements recorded were as follows: the head-and-body length ranged from 9 to 11.5 centimetres (3.5 to 4.5 in), the tail length ranged from 9.5 to 13.5 centimetres (3.7 to 5.3 in), and ear length was between 1.4 and 1.7 centimetres (0.55 and 0.67 in). Weight ranges from 25 to 32 grams (0.88 to 1.13 oz). Basically dark brown on the back, the caenolestid may have a lighter underbelly.
This caenolestid has a relatively stronger cranium and shorter mandible, suggesting that it can feed on tougher material than can other shrew opossums. The rostrum is not as well-developed as in the long-nosed caenolestid. The dental formula is 4.1.3.43.1.3.4. The long, blade-like structure of the molars and premolars could suggest a diet of soft invertebrates. The pattern of tooth eruption appears to be largely consistent in all caenolestids – the eruption of procumbent (trailing along the surface without spreading out roots) incisors, followed by the development of closely spaced incisors that distance from one another as the mandible grows, and then the eruption of molars and premolars. Like most caenolestids, it may have dental anomalies such as missing or supernumerary teeth. The study noted several differences in the dentition of the Incan caenolestid and common shrew opossums.
The Incan caenolestid is known to occur in elfin forests, secondary forests, Baccharis scrubs, and at altitudes ranging from 2,100 to 3,600 metres (6,900 to 11,800 ft) above the sea level in moist habitats. It is found mainly in the southern Peruvian Andes, and its range extends from southeastern Peru to the extreme west of Bolivia in northwestern South America. The Incan caenolestid is classified as least concern by the IUCN due to its wide distribution in its local habitat, presumably large population, and occurrence across several protected areas. There are no major threats to its survival.
Little is known of the behavior of the Incan caenolestid. Observations suggest it is terrestrial and nocturnal. Like other caenolestids, it feeds on insects and small invertebrates. It is known to host several ectoparasites, such as Pterygodermatites.
