An unusual pattern of copulatory behavior in a South American cricetid rodent: Akodon molinae

We describe the copulatory behavior and the morphology of the male genital tract of a member of a tribe (Akodontini) for which no information on copulatory behavior has been available. Copulation in Akodon molinae is characterized by multiple intromissions with no intravaginal thrusting, a single ejaculation, and a brief lock with the deposit of a plug. This pattern is unusual because of the combination of locking with both multiple intromissions and plugs. The latter combination, and similar standard measures of copulatory behavior, have been reported for Acomys cahirinus, a murid that frequently shows more than 1 ejaculation. Also, the standard measures of copulation in A. molinae resemble those of Calomys callosus, another South American cricetid, which shows intravaginal thrusting and infrequent locks. The functional significance and the anatomical correlates of locking and plug deposition in this species are discussed.