During the study of the metazoan parasites of fishes from Araguaia River, municipality of Araguatins (05 degrees 39'S, 48 degrees 07'W), State of Tocantins, Brazil, a third stage larvae of an undescribed species of Terranova were collected from the mesenteries of Plagioscion squamosissimus. These larvae were characterized to present large size, excretory pore situated near of the base of ventrolateral lips, presence of short intestinal caecum dorsal to oesophagus, ventriculus less than seven times as long as wide and absence of mucron. This is the first record and description of larval of species of Terranova parasitic in South American freshwater fishes.