Ameson metacarcini sp. nov. (Microsporidia) infecting the muscles of Dungeness crabs Metacarcinus magister from British Columbia, Canada
Bibliographic record
Abstract
The Dungeness crab Metacarcinus magister supports a large and valuable fishery along the west coast of North America. Since 1998, Dungeness crabs exhibiting pink- to orange-colored joints and opaque white musculature have been sporadically observed in low prevalence from the Fraser River delta of British Columbia, Canada. We provide histological, ultrastructural, and molecular evidence that this condition is caused by a new microsporidian parasite. Crabs displaying gross symptoms were confirmed to have heavy infections of ovoid-shaped microsporidian spores (~1.8 × 1.4 µm in size) within muscle bundles of the skeletal musculature. The parasite apparently infected the outer periphery of each muscle bundle, and then proliferated into the muscle fibres near the centre of each infected bundle. Light infections were observed in heart tissues, and occasionally spores were observed within the fixed phagocytes lining the blood vessels of the hepatopancreas. Transmission electron microscopy (TEM) revealed multiple life stages of a monokaryotic microsporidian parasite within the sarcoplasm of muscle fibres. Molecular analysis of partial small subunit rRNA sequence data from the new species revealed an affinity to Ameson, a genus of Microsporidia infecting marine crustaceans. Based on morphological and molecular data, the new species is distinct from Nadelspora canceri, a related microsporidian that also infects the muscles of this host. At present, little is known about the distribution, seasonality, and transmission of A. metacarcini in M. magister.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".