Diversity of spermatozoan morphology in two families of Branchiobdellida (Annelida: Clitellata) from North America
Bibliographic record
Abstract
The spermatozoa of 13 species belonging to seven different genera of the branchiobdellidan families Cambarincolidae and Bdellodrilidae (Annelida: Clitellata) were examined and compared with previously described members of the family Branchiobdellidae. Based on an examination of the spermatozoa in this relatively large number of species within the order, the variation in sperm morphology is now known to be much greater than was previously expected. Considerable variation was found in nearly all characters examined: the acrosome varied in length from 3 to 60 µm and in shape from straight for most of its length to twisted for its whole length. The nuclei also varied in size (from 4 to 22 µm) and in shape from straight to twisted. Four parallel but twisted mitochondria were present in all species examined, and differed only in length. The marginal fiber that coiled around the flagellum varied in size and pitch. By comparing the present data with those from other branchiobdellidans, we found that the apical concavity of the nucleus, the presence of the marginal fiber of the tail, and the absence of a true basal body with the central apparatus of the flagellum penetrating the midpiece mitochondria are the only characters common to all members of the Branchiobdellida. Sperm characters in this taxon are extremely variable, even within a single genus, thus making the definition of "a single" sperm model for the whole group highly problematic. However, the new data will be of significant value in future phylogenetic work.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 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) | 0.002 | 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 teacher head, 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".