An SSU rDNA barcoding approach to the diversity of marine interstitial cercozoans, including descriptions of four novel genera and nine novel species
Bibliographic record
Abstract
Environmental DNA surveys have revealed a great deal of hidden diversity within the Cercozoa. An investigation into the biodiversity of heterotrophic flagellates in marine benthic habitats of British Columbia, Canada, demonstrated the presence of several undescribed taxa with morphological features that resemble the cercozoan genera Cryothecomonas and Protaspis. Nine novel species of marine interstitial cercozoans are described that are distributed into five genera, four of which are new. Phylogenetic analyses of small subunit rDNA sequences derived from two uncultured isolates of Protaspis obliqua and nine novel cercozoan species (within four novel genera) provided organismal anchors that helped establish the cellular identities of several different environmental sequence clades. These data, however, also showed that the rarity of distinctive morphological features in cryomonads, and other groups of cercozoans, makes the identification and systematics of the group very difficult. Therefore, a DNA barcoding approach was applied as a diagnostic tool for species delimitation that used a 618 bp region at the 5' end of the SSU rDNA sequence. Nucleotide sequence analysis of this region showed high intergeneric sequence divergences of about 7% and very low intraspecific sequence divergences of 0-0.5%; phylogenetic analyses inferred from this barcoding region showed very similar tree topologies to those inferred from the full-length sequence of the gene. Overall, this study indicated that the 618 bp barcoding region of SSU rDNA sequences is a useful molecular signature for understanding the biodiversity and interrelationships of marine benthic cercozoans.
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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 | 0.001 |
| 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 | 0.000 | 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".