Cryptic speciation in the “<i>Marshallora nigrocincta</i>” species complex (Gastropoda, Triphoridae) from the Western Atlantic
Bibliographic record
Abstract
Marine gastropods of the “Marshallora nigrocincta” species complex range from southeastern Canada to southern Brazil, comprising M. nigrocincta, described from the northeastern United States, and Marshallora modesta, from the Caribbean. This study aims to disentangle this complex, elucidating how many species are indeed present in the western Atlantic, and whether M. nigrocincta is different from M. modesta. The mitochondrial markers COI and 16S were congruent in splitting the complex into six lineages: one belonging to M. nigrocincta (mainly from eastern United States), other two lineages related to M. cf. modesta (one from Florida, USA, and the second from Colombia), and three undescribed species from Brazil. Intra- and interspecific genetic distances, respectively, vary from 0–2.7%/6.3–13.5% (COI). The nuclear gene 28S was conservative to separate Marshallora sp. A (Brazil) from M. cf. modesta 2, but recognized M. cf. modesta 1, M. nigrocincta, and Marshallora sp. B (Brazil). The shell morphology is highly variable, but the presence of three basal cords seems to occur only in M. nigrocincta. The radular morphology exhibits a wide variation in the number of cusps of the central and lateral teeth. The new species herein identified will require formal descriptions following further fieldwork efforts, since the selected voucher material was lost during a fire. New generic allocations are made to Marshallora amicorum comb. nov., Marshallora pusilla comb. nov., and Marshallora medinae comb. nov., which is regarded as nomen dubium. This study may stimulate the incorporation of DNA analysis in the systematics of Triphoroidea, improving the knowledge about its biodiversity.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".