Thomasomys shallqukucha is a species of rodent in the genus Thomasomys known from the Andes of northern Peru. It consists of populations that were identified as Thomasomys cinereus until they were identified as a new species in 2023.
The species occurs in montane forests of a small area of the Department of Lambayeque in northern Peru, at an elevation of 2550mto3330mm (8,370feetto10,930feetm). The animal eats insects and seeds. The scientific name comes from the local dialect of the Quechua language and combines the words shallqua, referring to the Jalca biome, and ukucha for "rodent" (compare the Ecuadorian species Thomasomys ucucha).
Thomasomys shallqukucha is medium in size for its genus, with a head-body length of 116mm142mm. Characteristic traits include dark brownish fur, dark surfaces of the feet, a long, one-colored tail, and relatively short incisive foramina, an opening in the palate.