Holochilus

Holochilus is a genus of semiaquatic rodents in the subfamily Sigmodontinae, commonly known as marsh rats. These South American native rodents are found in grasslands, savannas, and marshes. The genus currently contains two recognized species: Holochilus brasiliensis and Holochilus chacarius. Historically, other species were included in Holochilus, but they have since been reclassified into different genera.

Holochilus rodents are characterized by their partially webbed feet, which are adaptations for their semi-aquatic lifestyle. They are skilled swimmers and spend a significant amount of time foraging in and around water bodies. Their diet consists mainly of vegetation, including grasses, sedges, and aquatic plants, though they may also consume insects and small invertebrates. These rodents are typically nocturnal or crepuscular, meaning they are most active during the night or at dawn and dusk. They build nests from plant material, often in burrows near water or in dense vegetation. Breeding occurs throughout the year in many parts of their range, with females typically giving birth to litters of several pups. The genus Holochilus is considered to be of Least Concern by the IUCN, though specific population trends can vary regionally.