Synodontidae

Synodontidae View in CoL View at ENA ( Aulopiformes ) ( Fig. 18A–C View Figure 18 )

In our specimen of Saurida brasiliensis there is a single, large cartilage situated on the distal diastemal edge of hypural 2, from where it tapers ventrally with a median process all along the distal margin of hypural 2 ( Fig. 18A, B View Figure 18 ). The bases of the upper three caudal fin rays of the lower lobe are different from the regular caudal fin rays: a dorsally directed process of the second uppermost ray of the lower lobe fits into a notch formed by a dorsal and ventral process of the base of the uppermost ray from the same lobe. The second ray has also a ventrally tapering process that overlaps the base of the ray ventral to it (third ray counted from the diastema). The respective cartilage serves as support for these three rays. It nevertheless remains unclear if this cartilage is a CMC due to its position or even if this finding in our S. brasiliensis specimen shows the regular condition: the same fin-ray configuration was found in our two specimens of Saurida gracilis , but in these specimens, cartilage did not stain well, so we refrain from drawing a conclusion on the identity and bearing of this cartilage in S. brasiliensis .

In Trachinocephalus myops a diastema is well visible, but there are no CMCs ( Fig. 18C View Figure 18 ). The lowest ray of the upper caudal lobe articulates directly in the diastema, but without cartilaginous support ( Fig. 18C View Figure 18 ). In Harpadon microchir the distal part of hypural 3 has a laminar extension that restricts the diastema caudally. There are also no CMCs present.