A new species of <i>Buchia</i> (Bivalvia: Buchiidae) from British Columbia, Canada, with an analysis of buchiid bipolarity
Bibliographic record
Abstract
Critical reinvestigation of the bivalve Buchia cf. blanfordiana Jeletzky, 1965 from the Upper Jurassic of western British Columbia indicates that it is morphologically distinct from B. blanfordiana Stoliczka, 1866 of the Indo-Pacific region. We analyzed collections from relatively coeval sections containing multiple buchiid species from the Northern and Southern Hemispheres and used ten morphological characters to describe Buchia shell shape and size. We tested for taxonomic differences on left and right valves using a traditional morphometric approach with both linear and angular measurements and Fourier (outline) analyses. Phenetic discrimination revealed considerable overlap in the morphospace, but high classification rates between the two groups when compared with a step-wise discriminant analysis. This study supports the retention of the Indo-Pacific genera Australobuchia Zakharov, 1981 and Malayomaorica Jeletzky, 1963 and confirms that Buchia (=Australobuchia) blanfordiana is restricted to the Southern Hemisphere. Consequently, we propose the new name Buchia columbiana n. sp. for material assigned to Buchia cf. blanfordiana Jeletzky, 1965. Our results have implications for bipolarity and migration of the genus Buchia, supporting previous suggestions that buchiids formerly identified as Buchia from the Southern Hemisphere should be grouped as a separate genus.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.005 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".