The skull of the bizarre mudpuppy (Necturus) under review

Updated March 17, 2021
with the addition of Proteus and new identifications for several bones in Necturus.

Necturus maculosus (Rafinesque 1818, Fig. 1) is the extant mudpuppy, a salamander with gill slits.

Strangely,
the maxilla is absent (Fig. 1). The ectopterygoid is ventral to the pterygoid. All jaw bones that reach the margin have large teeth. the postorbital and postfrontal are both stretched out.

On the palate,
the choana (internal naris, Fig. 1) is barely open and it does not have a posterior border. A central opening perforates the anterior palate. Otherwise the parasphenoid is wider than in any other taxon. It creates a nearly solid palate.

On the mandible,
both the dentary and the coronoid have teeth.

Sister taxa  
do not have such a long premaxilla. Similarly online images do not identify the palatine, but label the entire bone a vomer. Traditionally and in sister taxa vomers do not extend to the lateral skull. Thus, several skull bones here are reidentified based on homologs with sister taxa. Thus Necturus is not quite as bizarre as dissection guides indicate.

Figure 1. Necturus skull and in vivo. The maxilla is missing. Note the pterygoid and ectopterygoid are fused. The ectopterygoid has large teeth aligned with the palatine teeth. The frontal is divided in two.

Figure 1. Necturus skull and in vivo. The maxilla is missing. Note the pterygoid and ectopterygoid are fused. The ectopterygoid has large teeth aligned with the palatine teeth. The frontal is divided in two.

Postcranially,
pedal digit 5 is absent, distinct from all sister taxa. In the large reptile tree (LRT, 1471 taxa) Necturus nests between Rana, the bullfrog, and Andrias, the Chinese giant salamander.


References
Rafinesque CS 1818. The American monthly magazine and critical review 4: 41.\

wiki/Necturus

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