Are morphological characters distinctive enough to discriminate between two species of freshwater eels, Anguilla celebesensis and A-interioris?

To test the reliability of morphological keys for identifying two freshwater eel species, Anguilla celebesensis and A. interioris, mitochondrial DNA sequences were analyzed. Of eleven specimens examined five were from Sulawesi and six from New Guinea. Specimens were morphologically identified as ten A. celebesensis and one A. interioris. However, mitochondrial DNA sequence analysis indicated the existence of two genetically distinct groups, which corresponded exactly to the sampling localities. This contradiction might be attributable to inadequate descriptions of the anguillid species, for which intra-specific variations have been significantly underestimated. New approaches, such as molecular analysis, are necessary for species' identification of freshwater eels.