Length: typically 5-8 mm in the genus
New World hoppers formerly placed in genus Oliarus were split from that genus, and placed into a new, exclusively New World genus named Melanoliarus. The female hopper in the photo appears to be of that genus, though it is hard to be sure without a specimen. Members of the tribe Pentastirini, including Melanoliarus species, have five carinae (ridges) on the mesonotum, while species in tribe Cixiini have three.
Determined by Dr. Lois O'Brien, Green Valley, Arizona.
Photo location: Along the Rupununi River, Guayana.
American Insects site