The spot-flanked gallinule (Porphyriops melanops) is a species of bird in the family Rallidae. It is monotypic in the genus Porphyriops. It is found in Argentina, Bolivia, Brazil, Chile, Colombia, Paraguay, Peru, and Uruguay.

Its natural habitats are swamps and freshwater lakes, but it is able to survive in properly managed artificial ponds. Its population has declined significantly in recent decades.

The spot-flanked gallinule has a W chromosome that is larger than its Z chromosome, which is unique among bird species.

The spot-flanked gallinule weighs between 154 and 225 grams, with an average length of 28 cm, often described as a small waterfowl-like bird. Its head, chin, neck and breast feathers are a slate gray, contrasting with the black forehead and crown, extending to the top of the nape. Its covert feathers are a brown, cocoa-like, color while primary feathers tend to have a slight color contrast and are a darker shade of brown. As the name suggests, the flanks of this species is brown with white mottling with its rump a mix of the same shades of brown and white. Juveniles do not have any contrasting plumage and are typically entirely black before developing brown feathers followed by the other distinctive mature features. Most noticeably, the spot-flanked gallinule is often called the Green-Billed Tingua in Spanish due to its pale green beak which develops as it ages from a black and pink juvenile beak. Its legs are a drab green-gray color and are rarely visible as it spends a majority of its time in the water. Its iris changes from black as juvenile, to different shades of brown to its eventual, mature, vibrant red color.