The Cenozoic gonyaulacacean dinoflagellate genera<i>Operculodinium</i>Wall, 1967 and<i>Protoceratium</i>Bergh, 1881 and their phylogenetic relationships
Bibliographic record
Abstract
To clarify the systematic positions of the important gonyaulacacean generaOperculodiniumWall, 1967 emend. Matsuoka et al., 1997 andProtoceratiumBergh, 1881, we present in detail the tabulation of the Oligocene–Pleistocene, thermophilic, cyst-defined speciesOperculodinium bahamenseHeadinHead and Westphal, 1999 emend., and the extant, cosmopolitan, theca-defined speciesProtoceratium reticulatum(Claparède and Lachmann, 1859) Bütschli, 1885. Both species have a sexiform hyposomal tabulation, and L-type (Protoceratium reticulatum) or modified L-type (Operculodinium bahamense) ventral organization.Protoceratium reticulatumhas dextral torsion of the hypotheca, requiring assignation of the genus to the subfamily Cribroperidinioideae Fensome et al., 1993, whereasOperculodinium bahamensehas neutral torsion requiring assignation to the subfamily Leptodinioideae Fensome et al., 1993. The stratigraphic range of this subfamily is now extended upwards to the lower Pleistocene. Paradoxically,Protoceratium reticulatumproduces a cyst whose morphology is circumscribed by the cyst-defined genusOperculodinium, either implying polyphyletic origins for this genus or that combinations of ventral organization and torsion used to subdivide the family Gonyaulacaceae cannot always be applied rigidly. In detail,Operculodinium bahamenseis shown to have an unusual ventral tabulation in which the first apical plate contacts the apical pore complex but not the sulcus. The new term “episert” is proposed to describe this plate relationship, which appears to have evolved independently in several lineages of the suborder Gonyaulacineae.
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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 | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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".