Gerardo R. Cueto

New data on the natural history and morphometrics of Lutreolina crassicaudata (Didelphimorphia) from central-eastern Argentina

Emiliano Muschetto, Gerardo R. Cueto, Olga V. Suárez

We provide new data on the natural history and morphometrics of one of the least studied didelphid marsupial species, Lutreolina crassicaudata. Field work was conducted in central-eastern Argentina during two consecutive years. Juveniles and sub-adults were captured during summer and autumn. Reproduction showed seasonality with a continuous breeding period from spring to summer (September to February). The analysis of 17 scats belonging to 17 individuals showed mainly seeds and vegetal remains, as well as amphibians, birds and invertebrates. Sexual dimorphism in juveniles and sub-adults was registered for the first time, being males larger and heavier than females.

Nuevos datos sobre la historia natural y morfometría de Lutreolina crassicaudata (Didelphimorphia) del centro-este de la Argentina. En este trabajo proporcionamos nuevos datos sobre la historia natural y morfometría de una de las especies de marsupiales didélfidos menos estudiadas, Lutreolina crassicaudata. El trabajo de campo se llevó a cabo en el centro-este de la Argentina durante dos años consecutivos. Los individuos juveniles y subadultos fueron capturados durante el verano y el otoño. La reproducción mostró estacionalidad, con un período de crianza continuo durante primavera y verano (septiembre a febrero). El análisis de 17 heces pertenecientes a 17 individuos presentó principalmente semillas y restos de vegetales, como así también anfibios, aves e invertebrados. Se registró dimorfismo sexual en las clases de edad juveniles y subadultos, siendo los machos más grandes y pesados que las hembras.

Sexual dimorphism according to age in Oxymycterus rutilans (Rodentia, Muridae)

Olga V. Suárez, Gerardo R. Cueto, Fernando O. Kravetz

Sexual dimorphism in cranial morphology was studied in a population of Oxymycterus rutilans from the Paraná Delta, Argentina. Individuals were assigned to three categories on the basis of toothwear. Condylobasal length, length of the diastema, maximum incisor width and length of the maxillary molar row provided quantifiable differences among age groups. The stepwise discriminant analysis showed sexual dimorphism in the cranial dimensions for all age classes of O. rutilans specimens. Cranial length measurements maximised the differences between sexes, with males’ being longer than females’ for all age classes.