This is a large, highly distinctive freshwater turtle characterized by its hydrodynamic, oval, and dorsoventrally flattened carapace, which can reach lengths of 14 to 18 inches (35 to 45 centimeters) in mature adults, with an average weight of up to 11 pounds (5 kilograms). The carapace is typically dark gray to olive-brown with a bright, pale yellow margin that outlines the entire shell. Its plastron is cream or pale yellow and features a complex, symmetrical pattern of dark, rounded blotches. The flat head is light gray or greenish-gray, bisected by a prominent, pitch-black stripe that runs from the tip of the snout, through the eye, and down the side of the neck. Most notably, two prominent, light-colored sensory barbels dangle from the lower jaw, serving as tactile organs in murky waters. Its robust limbs are heavily webbed and equipped with sharp, powerful claws adapted for aquatic locomotion.

Geographical distribution: It is native to the temperate and subtropical watersheds of southeastern South America. Its geographic range encompasses southern Brazil (specifically the states of Rio Grande do Sul and Santa Catarina), throughout the territory of Uruguay, parts of eastern Paraguay, and northeastern Argentina, where it is widely recorded in the provinces of Buenos Aires, Entre Ríos, Corrientes, Santa Fe, Chaco, Formosa, and Misiones.

Habitat: This semi-aquatic species populates lentic and slow-moving freshwater ecosystems. It exhibits a strong preference for shallow lagoons, marshes, swamps, slow-flowing rivers, and creeks with muddy substrates and abundant organic debris. It relies heavily on environments with dense floating and submerged vegetation, as well as emergent logs, rocks, or sandy banks that provide suitable platforms for thermoregulation.

Feeding: It functions primarily as an opportunistic carnivore with omnivorous tendencies. Its diverse diet consists mainly of small fish, aquatic insects and their larvae, freshwater snails, crustaceans, and amphibians. It will also opportunistically consume small mammals, carrion, drowning terrestrial invertebrates, and small amounts of aquatic macrophytes when animal prey is scarce.

Behavior: Exhibiting diurnal habits, this turtle spends a significant portion of its day engaged in basking behavior (heliothermy) on logs, rocks, or grassy banks to regulate its body temperature. Despite its relatively large size, it is incredibly shy and wary of disturbance. At the slightest hint of danger, it will rapidly plunge into the water and bury itself in the soft, muddy bottom. It is an exceptionally graceful and fast swimmer due to its fully webbed feet.

Reproduction: The mating season occurs during the spring and early summer months, typically spanning from October to February. Courtship and copulation take place entirely underwater. Following successful mating, females migrate inland to find sandy or loose soil habitats near water bodies to excavate deep nests using their hind limbs. They lay a single clutch containing 10 to 32 hard-shelled, spherical eggs. The incubation period is highly temperature-dependent, lasting anywhere from 70 to 150 days before the brightly colored hatchlings emerge.

Conservation status: It is currently listed as Least Concern (LC) on both regional and global conservation scales due to its broad distribution and stable populations. However, localized populations face threats from habitat degradation, wetland drainage for agriculture, water pollution, and the illegal pet trade, which targets juveniles for their striking facial markings.