Ctenomys mendocinus

DIAGNOSIS. Ctenomys mendocinus (Fig. 1) can be distinguished from most medium-sized neighboring congeners by its dorsal pelage, which is light brown to reddish gray with transverse black waves along back of neck that disappear toward dirty white ventral region and by its whitish tail with dorsal median line of longer black hairs on apical half (Philippi 1869). Tail of C. mendocinus is shorter than tails of nearest geographical congeners C. eremophilus and C. validus. Skull of C. mendocinus (Fig. 2) is smaller than skull of C. validus, larger than that of C. eremophilus (Rosi et al. 1992b), and flatter and broader than those of neighboring congeners from La Pampa (C. azarae—Thomas 1903) and San Juan Provinces (C. johannis, C. tulduco—Thomas 1921a, 1921b). C. mendocinus is smaller than C. johannis and has larger cheekteeth (Thomas 1921b). Lateral borders of palate of C. mendocinus are separated more from rows of cheekteeth than those of C. azarae (Thomas 1903), and incisors are broader with darker fronts. Bullae of C. mendocinus differ markedly from long, low, and narrow bullae of C. pontifex (Thomas 1918) and are slightly smaller than bullae of C. azarae, C. johannis, and C. tulduco (Thomas 1903, 1921a, 1921b).