The Collaborative International Dictionary of English v.0.48:

Tuko-tuko \Tu"ko-tu*ko\, n. [From the native name .] (Zool.)
   A burrowing South American rodent (Ctenomys Braziliensis).
   It has small eyes and ears and a short tail. It resembles the
   pocket gopher in size, form, and habits, but is more nearly
   allied to the porcupines. [Written also tucu-tuco.]
   [1913 Webster]