Phenacogaster apletostigma sp. nov. is distinguished from all other species of the genus by the presence of a large and vertically elongate humeral blotch, extending from the lateral line to near the dorsum. Anterodorsal portion of humeral blotch with an anterior extension. The unique shape and size of the humeral blotch, not found in the remaining Phenacogaster species, is considered an autapomorphy of the new species. It is known from the River Araguari basin, Amapá State, Brazil.
Biodiversity; neotropical fishes; taxonomy
