SYSTEMATIC IMPLICATIONS OF CRANIOMETRIC VARIATION IN PROECHIMYS-IHERINGI THOMAS (RODENTIA, ECHIMYIDAE)

Proechimys iheringi is an echimyid rodent that ranges in distribution from the state of Bahia to the state of Sao Paulo in southeastern Braz il. The current taxonomic treatment of P. iheringi stems from MOOJEN ( 1948), and includes a formal subspecific structure and an alternative hypothesis which postulates various levels of differentiation and isol ation between geographic populations of R iheringi. According to the f ormal structure six subspecies are recognized primarily on the basis o f increasing number of cheekteeth counterfolds from northern to southe rn localities, whereas under the alternative hypothesis two forms, P. i. iheringi and P. i. paratus, arc regarded as specifically isolated. We examined variation in cranial morphometric traits in all subspecies recognized by MOOJEN (1948), in addition to P. i. eliasi, a new form recently described from the state of Rio de Janeiro (PESSOA and REIS 1 993). Cranial variation as revealed by multivariate analysis is not co ngruent with the formal subspecific structure but rather supports MOOJ EN'S (1948) conjecture that P. i. paratus and P. i. iheringi may be sp ecifically differentiated. The remaining forms currently recognized as P. i. denigratus, P. i. gratiosus, P. i. panema, P. i. bonafidei, and P. i. eliasi may be part of another taxon specifically distinct from P. i. paratus and P. i. iheringi.