Taxonomy & naming
Paratrygon lucindai was described by Loboda in 2026 in a single Neotropical Ichthyology paper that simultaneously named four new species of Paratrygon, each endemic to one of the four largest clear-water rivers of the Brazilian Crystalline Shield: the Tocantins (P. lucindai), Araguaia (P. araguaia), Tapajós (P. munduruku) and Xingu (P. raonii). The description raised the genus from three previously recognized species, P. aiereba, P. orinocensis and P. parvaspina, to seven, and is placed in family Potamotrygonidae, subfamily Potamotrygoninae, order Myliobatiformes.
The holotype is an adult male, UNT 7469, 19.88 in disc width, collected from the rio Tocantins near its confluence with the rio Manoel Alves, Municipality of Ipueiras, Tocantins State, Brazil (11°19'S, 48°28'W) in January 2004, and is held with the paratype series at the Universidade Federal do Tocantins (UNT). Molecular work by earlier authors (Fontenelle et al., 2021) had already flagged Tocantins-basin Paratrygon as genetically distinct from typical P. aiereba, tentatively as "P. aiereba – Rio Tocantins"; the 2026 paper formalizes that lineage as its own species using coloration, dentition, dermal-denticle morphology, lateral-line canal architecture and skeletal characters, alongside the earlier molecular signal. Catalog of Fishes (Eschmeyer, CAS) is the authority for the valid name used here.
Morphology
Paratrygon lucindai has the disc-flat body plan of its genus: a large, rounded pectoral disc with the eyes and paired spiracles set on the dorsal surface and the mouth, nostrils and gill slits ventrally. The holotype male measured 19.88 in disc width; adult specimens examined in the description averaged 23.39 in and reached 31.54 in disc width (roughly 23.2–31.5 in), with total length (including the long, whip-thin tail) averaging 28.92 in and reaching 37.44 in.
The diagnostic coloration is dorsal disc gray, dark gray, brown, dark brown or reddish brown, patterned with large round spots — beige, gray, brown, dark brown or reddish brown, two to three times the diameter of the spiracle, sometimes five to six times — scattered across the disc and more evident toward the fin margins; small vermiculated dark spots occur in some specimens as well. This spotting distinguishes it from the small-spotted P. aiereba and from the very dark, vermiculated coloration of P. munduruku and P. raonii. Spiracles are small and rounded (mean 4.4% disc width) with a small, globular spiracular process. As in the rest of the family, males carry paired claspers and a serrated venomous spine sits near the tail base; P. lucindai has one of the thinnest caudal stings recorded in the genus.
Habitat
Paratrygon lucindai is endemic to the upper and middle portions of the rio Tocantins and its tributaries in Tocantins State, Brazil. The Tocantins is one of the Amazon basin's major "clear water" rivers, rising from the weathered Precambrian soils of the Brazilian Crystalline Shield rather than the sediment-laden Andes; clear-water rivers of the eastern Amazon are relatively transparent, olive-green in color, slightly acidic (pH roughly 6.0–6.8) and carry very little suspended sediment or dissolved mineral load — the nearby Tapajós, a comparable system, measures a conductivity of only about 14 μS/cm.
This is a sharply different chemical environment from the muddy, whitewater channels of the central Solimões-Amazonas system that the widespread P. aiereba occupies, and the describing paper argues that this basin-scale contrast in water chemistry between clear-water and white-water rivers is itself a plausible driver of diversification within Paratrygon. Like the rest of its family, P. lucindai is a benthic species that respires through the spiracles on top of its head while resting on or partly buried in the substrate.
Feeding
No dedicated dietary study of Paratrygon lucindai has been published; the description is a taxonomic and morphological revision rather than an ecological one. What is known comes from the biology shared across the family (Potamotrygonidae): river stingrays are benthic ambush predators that use the electro-sensory ampullae of Lorenzini, densely distributed on the ventral disc, to detect the faint bioelectric fields of prey hidden in or on the substrate.
Across the genus and family, the diet centers on bottom-dwelling invertebrates — aquatic insect larvae, crustaceans, molluscs and worms — supplemented with small fishes where available, taken by pinning prey beneath the disc and working it to the crushing tooth plates in the ventral mouth. There is no species-specific feeding data for P. lucindai beyond this family-level pattern.
Mating
As in all elasmobranchs, fertilization in Paratrygon lucindai is internal: a male grips a female's disc, typically biting at the margin, and inserts one of his paired claspers to transfer sperm. No courtship or mating observations specific to this species have been published — the 2026 description is a morphological revision based on preserved museum material, not a field or captive-breeding study.
This reproductive mode is uniform across Potamotrygonidae, so the general pattern — vigorous courtship with disc-margin biting, no pair bond, and no male role after mating — can be stated with confidence even though it has not been directly observed in this particular species.
Breeding
Paratrygon lucindai is presumed viviparous, like every member of its family, nourishing developing embryos after the small yolk supply is exhausted through matrotrophic histotrophy — a protein- and lipid-rich uterine secretion ("uterine milk") absorbed directly by the pups. This is documented across Potamotrygonidae generally; no litter-size, gestation-length or pupping data specific to P. lucindai have been published.
Given the very large adult size of this species (disc widths approaching 31.5 in), a small-litter, long-gestation reproductive strategy broadly similar to that described for the type species P. aiereba would be expected, but this remains an inference from the genus rather than a documented fact for P. lucindai itself.
In the aquarium
Paratrygon lucindai is not an aquarium fish. It was described from museum material only in 2026 and has no history in the trade; more fundamentally, the genus Paratrygon consists of exceptionally large, deep-bodied "discus rays" whose adult disc widths run 19.7–35.4 in or more, a scale that puts them beyond any home aquarium and squarely into the realm of large public displays and dedicated research collections — a fact that applies to the whole genus, not just this species.
Were specimens ever to reach the trade, the requirements would be extreme by any standard: many square metres of floor space, a deep bed of soft, fine sand for a species with a long, delicate whip-tail, warm and softly mineralized water held to a strict standard, and total avoidance of copper-based medication. The serrated venomous spine is a genuine medical hazard. Given the species' single-river endemism and its status as a 2026 description, any collection pressure for the aquarium trade would be difficult to justify.
Conservation
Paratrygon lucindai has not yet been formally assessed by the IUCN Red List; as a species described in 2026 it currently carries no Red List status. The describing authors, applying IUCN Red List criteria informally in their taxonomic paper, suggested a category of Least Concern, noting that P. lucindai is the best-represented of the four newly described clear-water Paratrygon in museum collections — it has been collected throughout the main channel of the upper and middle Tocantins and its tributaries — and that its populations do not appear to face imminent threats. This is the describing authors' own proposed assessment, not an official Red List determination.
The authors nonetheless flagged all four of the new clear-water Paratrygon species, including P. lucindai, as among the most vulnerable in the genus by virtue of their single-river endemism, in a region under mounting anthropogenic pressure — particularly the Tocantins-Araguaia system, which is heavily affected by damming, agricultural expansion and mining. A formal Red List assessment, and continued monitoring of the Tocantins basin, are the clear next steps for this recently recognized species.