The brown-banded water snake (Helicops angulatus ) is a species of aquatic snake found in tropical South America and Trinidad and Tobago. It is also known as the water mapepire.
The brown-banded water snake grows to a maximum total length (including tail) of 78 cm (31 inches). Dorsally, it is olive or gray-brown, with dark brown, black-edged crossbands, which narrow at the sides, and are usually confluent with the black crossbands of the belly. There is a large dark rhomboid on the nape. Ventrally, it is yellowish (in alcohol) with black crossbands or black spots.
The dorsal scales are strongly keeled, even on the occiput and nape, and are arranged in 19 rows. Ventrals are 102–130 in number, the anal scale is divided, and the 61-94 subcaudals are paired and keeled.
H. angulatus lives in fresh and brackish water, where it feeds on fish and possibly also freshwater eels, frogs, tadpoles, and lizards.
H. angulatus is a venomous snake, its venom causes rapid death in mice with an injection of 0.4 mg/kg (intraperitoneally).
H. angulatus has been reported to be "facultatively viviparous".
