Pseudis is a genus of South American frogs (swimming frogs) in the family Hylidae. They are often common and frequently heard, but easily overlooked because of their camouflage and lifestyle, living in lakes, ponds, marshes and similar waters with extensive aquatic vegetation, often sitting at the surface among plants or on floating plants, but rapidly diving if disturbed. Whereas the adults are medium-sized frogs, their tadpoles are large; in some species the world's longest. Distribution Pseudis species are distributed throughout tropical and subtropical South America, almost entirely east of the Andes (P. paradoxa is the only species with populations west of the Andes, in Colombia). They are found from Trinidad to northern Argentina, being absent only in Ecuador and Chile, highland regions, and the southernmost part of South America. All species occur in Brazil, and P. bolbodactyla, P. cardosoi, P. fusca and P. tocantins are endemic to this country. Description These frogs have several adaptations to aquatic life, such as protuberant eyes, robust hind limbs, and fully webbed feet. Nevertheless, they belong to the "true" tree frogs, family Hylidae. Breeding and feeding Mating and egg-laying in Pseudis is typical of frogs. What sets them apart is their tadpoles that start out as fairly normal, but continue growing until reaching gigantic sizes, sometimes as much as in length in P. paradoxa and P. platensis. They are the longest known tadpoles and also large compared to the adult frogs, which are in snout–to–vent length. Less data is available for the tadpoles of most others members of the genus, but they too reach large sizes, although perhaps somewhat less than P. paradoxa and P. platensis. Their adult frogs also average somewhat smaller with snout–to–vent lengths of . However, there are two outliers in the genus: The closely related P. cardosoi and P. minuta (equalling the proposed genus Podonectes, see Phylogenetic relationships) have more normal tadpoles that are not known to surpass lengths of . This is still large compared to the adults of these two species, meaning that they too "shrink" during metamorphosis from tadpole to frog. In most if not all the species, there are noticeable local variations in the final size of the tadpoles, with those in large temporary waters with plenty of food and few aquatic predators growing larger than those in smaller waters with less food or waters with more aquatic predators. In at least the species with very