ANÁLISIS DE LA VARIABILIDAD CRANEOMÉTRICA EN Ctenomys talarum (RODENTIA, CTENOMYIDAE)

Analysis of craniometric variation in Ctenomys talarum (Rodentia, Ctenomyidae). A morphometric analysis on the skull of five populations of Ctenomys talarum was performed; these populations represent the three subspecies recognized for this species of tuco-tuco (i.e. C. t. talarum, C. t. recesus y C. t. occidentalis). We analyzed the skull geographic variation and the sexual dimorphism. When studying the geographic variation, two types of discriminant analyses were performed: one from the raw data and another from scale-corrected data, after a method that removes the information related to size was applied. We observed a significant sexual dimorphism in C. talarum; in conse- quence analyses of geographic variation were conducted separately in males and females. Results from these analyses showed significant differences between populations that were mainly due to the overall size of the skull, both in males and females. After influence of size was removed, differences between populations (due to shape differences on the skull) were less significant. Likewise, the geographic craniometric variation observed was not in agreement with the three nominal species of C. talarum, therefore, these results do not support their recognition. In the genus Ctenomys, size is assumed to be a very important evolutive character, both at the intraspecific as well as the interspecific levels.