Morphological and molecular identification of <i>Saccoglossus</i> species (Hemichordata: Harrimaniidae) in the Pacific Northwest
Bibliographic record
Abstract
Hemichordates, especially enteropneust worms, have become increasingly important in phylogenetic studies to test theories of chordate evolution. However, there are many populations of enteropneusts along the Pacific Northwest coast of North America that have not been identified. Here we show that two common Pacific Northwest enteropneust species, Saccoglossus pusillus and Saccoglossus bromophenolosus, can be distinguished by both morphological and molecular characters, and we identify several populations of both species. We compare them with a closely related species, Saccoglossus kowalevskii, from the Atlantic coast of North America. We compile the morphological characters used to distinguish harrimaniid enteropneusts, and we describe a new staining method to examine the gill bars and proboscis skeleton of enteropneusts to aid in identification. Using 18S and 16S ribosomal DNA sequences, we determine that the range of S. pusillus extends from southern California, where the worm was first identified, to southern Canada. This previously unknown large range shows a dramatic geographic cline in adult body size, with the smallest populations found in the south and the largest adults near Vancouver Island. In contrast, S. bromophenolosus may be a Pacific Northwest species that was relatively recently introduced from the Atlantic Ocean.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 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".