A rare Macristium-stage Bathysaurus mollis (Aulopiformes, Bathysauridae) from the South Pacific

We describe a rare larva of the family Bathysaurus mollis which was collected off the coast of New Caledonia on November 30, 2014. Larval stages of the two species of the family Bathysauridae (B. mollis and B. ferox) are exceptionally rare and only 11 were reported for both species together including our specimen. In 1903 Regan described the first larva as a new species, Macristium chavesi, not aware that the individual is the larval form of a species already known to science, Bathysaurus ferox. Based on the larvae known to date, the size of the larvae ranges from about 20 mm to 127 mm standard length, indicating a long duration of the larval stage. Our larva is in exceptional condition and with 98.6 mm standard length on the larger side of the larval phase. We further summarize the literature and comment on the reduction of the maxilla in bathysaurids.

Automated summary

We report a rare larva of the family Bathysaurus mollis that was collected off the coast of New Caledonia on November 30, 2014. Larval stages of the family Bathysauridae are uncommon, and only 11 specimens have been reported for both species, including our own. Our larva is in exceptional condition, measuring 98.6 mm in standard length, which is on the larger side of the larval phase. Additionally, we summarize previous literature and provide commentary on the reduction of the maxilla in bathysaurids.