1 1Desert Community Ecology Research Team (Ecodes), National Institute for Research on Arid Zones (IADIZA), CCT Mendoza, CONICET, Casilla de Correos 507, 5500 Mendoza, Argentina; Instituto de Ciencias Básicas (ICB), Universidad Nacional
de Cuyo, Mendoza, Argentina
The first information on the gestation period, maternal behaviour, neonatal development and growth of the subterranean caviomorph rodent Ctenomys mendocinus Philippi, 1869, is reported herein. My hypothesis was that, despite its belonging to a typically precocial suborder, the life history traits of C. mendocinus would favour its altricial condition. The off spring of C. mendocinus were categorized as altricial by using two different classification systems. This condition was also reflected in maternal care. Females built large nests (2000 cm3) where, after a long gestation period (95.9 days), they gave birth to litters of blind pups, half-naked, with external ear meatus open and good physical coordination. The mothers suckled the off spring in long bouts (19.9 min), retrieved their pups, and these showed no tactics to reduce the suckling bout. Overall, evidence was consistent with the hypothesis analyzed, although particularities found, e.g. some precocial traits, suggest the existence in C. mendocinus of a trade-off between the constraints and advantages related to its subterranean way of life and the phylogenetic inertia typical of caviomorphs.