All salamanders possess anterior ventral glands (character 10, state 1) except the Sirenidae, indicating an independent loss of these glands in the Sirenidae (character 10, state 0).
In all salamanders, except for the Piethodontidae (Strickland, 1966; Williams et al, 1984), Rhyacotritonidae, and Sirenidae (Willett, 1965), a longitudinal duct (Bidder's duct or marginal longitudinal duct) connects the lumina of the multiple vasa efferentia and also serves to communicate the vasa efferentia leading immediately from the testes to the afferent epididymal ducts (Williams et al., 1984).
The afferent epididymal ducts empty into a renal corpuscle and, thus, are delineated grossly from the efferent epididymal ducts by a renal corpuscle in all salamanders except the Eurycinae (Williams et al., 1984), Rhyacotritonidae, and Sirenidae. The renal corpuscle and efferent epididymal ducts represent the remnant mesonephros that is modified for sperm transport.
The Rhyacotritonidae and Sirenidae (Willett, 1965) have identical genital kidney duct morphologies that are different from all other salamanders but similar to that of caecilians (Wake, 1970).
The simple condition is found only in the Proteidae (Rosenquist and Baker, 1967) and Sirenidae (Willett, 1965) and can also be considered the larval condition, as this condition is found in larval salamanders (Rodgers and Risley, 1938).
However, recent phylogenetic analyses concluded that these complex structures might have evolved independently due to the recovery of a paraphyletic Salamandroidea with respect to the placement of the Sirenidae within the traditional Salamandroidea (Larson, 1991; Gao and Shubin, 2001; Larson et al., 2003; Frost et al., 2006).
Thus, Willett (1965) predicted an affinity of the Sirenidae and Proteidae based on identical morphology of the pelvic kidney collecting ducts.
(2005) and Struck (2007) for optimization interestingly, the male genital kidney anatomy of the Rhyacotritonidae is identical to that of the Sirenidae (Willett, 1965), and the male pelvic kidney anatomy of the Rhyacotritonidae is identical to that of the Cryptobranchidae (Ratcliff, 1965) and Hynobiidae (Yamagiwa, 1924).