Description of a New, Narrowly Endemic South American Darter (Characiformes: Crenuchidae) from the Central Guiana Shield Highlands of Guyana
Bibliographic record
Abstract
Characidium amaila, new species, is described from rapids of the upper Kuribrong River (Potaro–Essequibo drainage) upstream of Amaila Falls. It is diagnosed from most other species of Characidium by lacking scales on the isthmus and chest, and by having 8–13 premaxillary teeth, the first four pectoral-fin rays noticeably thickened, 34–36 lateral line scales, and branchiostegal membranes that are free from each other across the isthmus. Characidium amaila is further distinguished by its large adult body size (max. = 85.5 mm SL), and by having a tan body base color with a dark midlateral stripe that originates on the upper lip and continues posteriorly to the base of the middle caudal-fin rays, a gray to dark-black dorsum with two horizontal rows of small light spots formed by aligned light-colored scale centers, a dark humeral spot, up to 15 irregular black bars that extend from dorsum to lower sides, a light opercular margin, and fins that are uniformly dusky. Several cranial, vertebral, and swim bladder characteristics also support distinctiveness of the new species.Characidium amaila es descrita de los rápidos de el alto río Kuribrong (cuenca del Potaro–Essequibo) aguas arriba de las Cascadas de Amaila. Se distingue de la mayoría de las otras especies de Characidium por la ausencia de escamas en el istmo y el pecho, y por tener 8–13 dientes premaxilares, por poseer los primeros cuatro radios de la aleta pectoral notablemente ensanchados, 34–36 escamas en la línea lateral, y por tener las membranas de los radios branquiostegales separadas del istmo. Characidium amaila se distingue además por el gran tamaño del adulto (max. = 85.5 mm SL) y por tener el cuerpo de color base café claro con una banda medio lateral que se origina en el labio superior y continúa posteriormente hasta la base de los radios medios de la aleta caudal; el dorso gris a negro con dos hileras horizontales de pequeños puntos claros formados por la alineación de los centros más claros de las escamas; una mancha humeral oscura; hasta quince barras negras irregulares que se extienden del dorso a la parte inferior de los flancos; el margen del opérculo de color más claro y aletas uniformemente grisáceas. Varios caracteres craneales, de las vertebras y de la vejiga natatoria apoyan el diagnostico de esta especie nueva.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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 source (direct Gemma or distilled Codex), 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".