Molecular phylogeny for the Neotropical freshwater stingrays (Myliobatiformes: Potamotrygoninae) reveals limitations of traditional taxonomy
Bibliographic record
Abstract
Abstract The subfamily Potamotrygoninae, the only extant clade of elasmobranchs exclusive to freshwater environments, encompasses four genera and 38 species distributed across almost every major South American river basin. Despite their importance in the ornamental fish trade, the taxonomy and evolutionary relationships within potamotrygonines have not yet been resolved. Here, we present a comprehensive molecular phylogeny for the Neotropical freshwater stingrays, based on extensive species and population sampling (35 species and > 350 individuals from drainages across South America). Our phylogeny corroborates the monophyly of the genera Paratrygon and Heliotrygon and the monophyly of the Potamotrygon + Plesiotrygon clade. Within the Potamotrygon + Plesiotrygon clade, we identify a core Potamotrygon clade characterized by short branches, low nodal support and incongruence with current species-level taxonomy. In the core Potamotrygon clade, specimens of widespread species, such as Potamotrygon motoro and Potamotrygon orbignyi, do not form monophyletic lineages; instead, specimens from these species are often closely related to those of other species from the same river basins. These patterns could be caused by inaccurate taxonomy, hybridization, incomplete lineage sorting and rapid diversification. We discuss the conservation of Neotropical freshwater stingrays from a phylogenetic perspective and suggest ways to prioritize potamotrygonid conservation efforts with respect to endemism and evolutionary distinctiveness.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".