The Guiana dolphin (also known as estuarine dolphin or costero) is a dolphin which lives alongside central and Southern America. It was agreed as a separate species back in 2007. It looks like a bottlenose dolphin (though smaller at 2.1m. They do not bowride, but avoid them.
It has an electroreceptive sense – the suggestion is that all toothed whales have this, but it is unclear. It was described as a separate species back in 1864 (from the Tucuxi). This was questioned for some time, but is certainly confirmed from now.
It is found in estuaries and similar up and down the coast. The population in Guanabara bay is currently near Rio de Janeiro, down from 70 in 1995 and 400 in 1985.
Below is some footage of some of these dolphins\