Taxonomy & naming
Paratrygon araguaia was described by Loboda in 2026, in the same Neotropical Ichthyology paper that simultaneously named three sibling species from the Tocantins, Tapajós and Xingu rivers, raising Paratrygon from three previously recognized species to seven. It is placed in family Potamotrygonidae, subfamily Potamotrygoninae, order Myliobatiformes.
The holotype, MZUSP 104390, is a juvenile female of 11.3 in disc width, collected from the rio Araguaia at the District of Luiz Alves, Municipality of São Miguel do Araguaia, Goiás State, Brazil (13°13'3.04"S, 50°35'07.86"W) in June 2005; the paratype series, also all juveniles ranging roughly 7.8–11.93 in disc width, comes from the same locality and from Município de Caseara further downstream in Tocantins State. Earlier molecular work (Frederico et al., 2012; Fontenelle et al., 2021) had already flagged this Araguaia-basin lineage as genetically distinct from typical P. aiereba; the 2026 description formalizes it using coloration, spiracle shape, dermal-denticle and skeletal characters. Catalog of Fishes notes that the species epithet was misspelled as "araguaiaensis" in the paper's own etymology section — the valid, correctly formed name is Paratrygon araguaia, and that is the name used here and by Catalog of Fishes (Eschmeyer, CAS), the authority followed on this site.
Morphology
Every specimen examined in the original description of Paratrygon araguaia was a juvenile, ranging from about 7.8–11.93 in disc width (roughly 7.9–11.8 in); the true adult size of the species is not yet documented. The disc is subcircular, averaging about 108% of its width in length, with a slightly concave anterior margin.
The dorsal disc is brown or dark brown and carries two distinct spot types: larger, more conspicuous pale spots in beige or light brown, rounded and roughly the size of the spiracle, and smaller dark, thread-like (vermicular) spots interspersed between them — a combination that separates P. araguaia from its close relatives P. munduruku and P. raonii, which are darker overall with only vermicular spotting, and from P. lucindai, which instead shows large round spots without the paler rounded type. The spiracles are comparatively large and rounded (mean 5.3% disc width) with a short, straight spiracular process, and the rostral cartilage projects further forward between the nasal capsules than in any other Paratrygon species. As in the rest of the genus, a serrated venomous spine sits near the tail base; in P. araguaia the sting is unusually thick for the genus.
Habitat
Paratrygon araguaia is endemic to the upper and middle rio Araguaia and its tributaries, spanning Goiás and Tocantins States in Brazil. The Araguaia is one of the Amazon basin's major clear-water rivers, rising from the weathered Precambrian soils of the Brazilian Crystalline Shield rather than from Andean sediment; such rivers run relatively transparent and olive-green, are slightly acidic (roughly pH 6.0–6.8) and carry very little suspended sediment or dissolved mineral load compared with whitewater systems.
This clear-water chemistry sets the Araguaia sharply apart from the muddy, sediment-rich channels of the central Solimões-Amazonas system occupied by the widespread P. aiereba, and the describing authors propose that this basin-scale difference in water chemistry between clear-water and white-water rivers may itself have driven diversification within the genus. As a benthic ray, P. araguaia respires through the spiracles atop its head while resting on the substrate, in the manner typical of the family.
Feeding
No dietary data specific to Paratrygon araguaia has been published; its 2026 description is a taxonomic and morphological revision of museum material, not a field or feeding study. What can be stated comes from the biology shared across Potamotrygonidae: these are benthic ambush predators that locate prey using the electro-sensory ampullae of Lorenzini on the ventral disc, which detect the faint bioelectric fields of animals hidden in the substrate.
Across the family the diet centers on bottom-dwelling invertebrates — aquatic insect larvae, crustaceans, molluscs and worms — supplemented opportunistically with small fishes, pinned beneath the disc and worked to the crushing tooth plates of the ventral mouth. No feeding observations exist for P. araguaia beyond this general family pattern.
Mating
As in all elasmobranchs, fertilization in Paratrygon araguaia is internal, accomplished when a male grips a female's disc — typically biting at the margin — and inserts one of his paired claspers to transfer sperm. No mating behaviour has been directly observed or published for this species; the 2026 description draws entirely on preserved juvenile specimens.
Because internal fertilization via claspers is uniform across Potamotrygonidae, this general reproductive mode can be stated with confidence for P. araguaia even without species-specific observations, though details of its courtship remain unknown.
Breeding
Paratrygon araguaia is presumed viviparous, in keeping with the rest of its family, nourishing developing pups after the egg yolk is exhausted through matrotrophic histotrophy — a nutrient-rich uterine secretion taken up directly by the embryos. This is documented across Potamotrygonidae in general; because the type series of P. araguaia consists entirely of juveniles, no adult reproductive data, litter sizes or gestation length have been recorded for this species.
The absence of any mature specimens in the founding description is itself notable: it means the adult form of P. araguaia, including its full disc width and reproductive biology, remains to be documented from future fieldwork on the Araguaia system.
In the aquarium
Paratrygon araguaia has no history in the aquarium trade — it was described only in 2026 from preserved museum material, all of it juvenile. More fundamentally, Paratrygon is a genus of unusually large "discus rays": its known species reach disc widths of 19.7–39.4 in or more as adults, a scale that places the genus beyond any home aquarium and into the domain of large public displays and dedicated research collections, a statement that holds for the genus as a whole rather than for this species specifically (whose adult size is not yet known).
Were specimens ever encountered in trade, the husbandry demands would be severe: many square metres of floor space, a deep bed of soft sand, warm and carefully controlled water chemistry, and total avoidance of copper-based medications, with the venomous tail spine a genuine hazard. Given the species' narrow, single-river endemism and its very recent description, there is no responsible basis for aquarium collection.
Conservation
Paratrygon araguaia has not been formally assessed by the IUCN Red List; as a species named in 2026 it currently carries no Red List status. The describing authors, applying IUCN criteria informally within their taxonomic paper, suggested a category of Data Deficient, noting that the species' full extent of occurrence in the Araguaia system is not yet known and that further research on its populations is needed. This is the describing authors' own proposed assessment, not an official Red List determination.
The authors singled out the four newly described clear-water Paratrygon species, including P. araguaia, as possibly the most vulnerable in the genus, precisely because each is endemic to a single river system in a region facing substantial anthropogenic pressure — a concern the authors raised with particular emphasis for the Tocantins-Araguaia system, which is affected by damming, agricultural expansion and mining. Basic distributional and population survey work is the clear priority for this recently recognized, still juvenile-only-known species.