In culmination, male urogenital duct structures support a monophyletic Salamandroidea; however, support weakens with the exclusion of male cloacal morphology.
In general terms, male salamanders with external fertilization (i.e., the Cryptobranchidae, Hynobiidae, and Sirenidae) have few or no cloacal glands whereas salamanders with internal fertilization (all other salamanders; i.e., Salamandroidea) have abundant cloacal glands.
Thus, here, we also test the hypothesis that male urogenital duct anatomy will support a more traditional salamander phylogeny with a monophyletic Salamandroidea over a more controversial phylogeny with a paraphyletic Salamandroidea.