Gyrinus gibbus
Gyrinus gibbus is a species of aquatic beetle in the family Gyrinidae. It is native to the Neotropics. Description 
The body of Gyrinus gibbus has an oval, convex shape and is between 4,5 mm and 6.0 mm long. It is coloured black or dark brown with exception of the elytral margin, which is often coloured in a reddish or yellow tone. The elytra are non-uniformly reticulated and vary from a polished appearance in the middle regions of the elytra to a bronze-metallic appearance towards the elytral margins. The species shows a high regional variability in body size, convexity, colouration and reticulation of the elytra, with specimens found in the Amazon region being less round and less convex. Like all Gyrinid beetles Gyrinus gibbus has horizontally divided eyes, allowing them to observe the surroundings underwater and on the surface alike. Gyrinus gibbus can be distinguished from the very similar Gyrinus ovatus by the harsher contrast between the polished and metallic areas on the elytra. Furthermore, the elytral apex of Gyrinus gibbus shows a complete border, while in Gyrinus ovatus the epipleural angle bears a spiky denticle. Feeding habits 

Gyrinus gibbus feeds on small insects and spiders. Distribution 
Gyrinus gibbus is distributed in many parts of Latin America, including Argentinia, Bolivia, Brazil, Colombia, Costa Rica, Ecuador, Mexico, Paraguay, Peru, Uruguay and Venezuela. Gyrinus gibbus prefers stagnant or slow flowing waters. In Venezuela the species seems to be strongly associated with streams and river habitats where it occurs in the calmer zones of those water bodies. References 

Gyrinidae
Beetles described in 1838
Beetles of South America
Aquatic insects