Pythonichthys asodes, sp. nov., is described from Panamá Bay. This is the first eel of the family Heterenchelyidae from the Pacific Ocean. P. asodes is placed in Pythonichthys on the basis of a complete inner row of maxillary teeth, lack of fleshy folds along
the posterior inner border of the maxilla, lack of a median dermal crest on the head, a relatively long head and trunk, and low vertebral count. It differs from all species of Pythonichthys in that the vomerine tooth row is continuous with the intermaxillary dentition, and the dorsal
origin is in advance of the pectoral girdle. A key to the four species of Pythonichthys is given.
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