2010: Age, body size, and sexual dimorphism in size and shape in Salamandrella keyserlingii (Caudata: Hynobiidae).
(eds.), Handbusch der Reptilien und Amphibien Europas, band 4/I Schwanzlurche (Urodela) I (Hynobiidae, Proteidae, Plethodontidae, Salamandridae I: Pleurodeles, Salamandrina, Euproctus, Chioglossa, Mertensiella).
Despite the similarity of the genital kidney to that of sirenids, the pelvic kidney of the Rhyacotritonidae is most similar to that of the Cryptobranchidae and the Hynobiidae (i.e., collecting ducts that communicate individually with the cranial portion of the cloaca), a condition that could be considered homoplastic in the context of our current understanding of salamander phylogeny.
The most complex condition, found in the Ambystomatidae, Hynobiidae, Proteidae, Salamandridae, and Siren idae, consists of the following ducts leading from the testes sequentially: the vasa efferentia, Bidder's duct (longitudinal collecting duct), afferent epididymal ducts, and efferent epididymal ducts.
in all other salamanders the collecting ducts bend caudally during development (Rodgers and Risley, 1938) and either anastomose and enter the cloaca (in the Plethodontidae and some Salamandridae; Francis, 1934; Baker, 1965; Strickland, 1966), anastomose and enter Wolthan ducts (in the Ambystomatidae, Amphiumidae, and some Salamandridae, Baker, 1945; Baker and Taylor, 1964; Baker, 1965), or enter the cloaca individually (in the Cryptobranchidae and Hynobiidae; Ratcliff, 1965; Yamagiwa, 1924).
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.
The major difference between the two topologies was the recovery of the Sirenidae as the basal salamander lineage (results in a monophyletic Salamandroidea; Wiens et al., 2005) or the recovery of the Cryptobranchidae + Hynobiidae clade as the basal salamander lineage and the Sirenidae as the sister taxon to Proteidae (results in a paraphyletic Salamandroidea; Struck, 2007).
Collecting ducts that do not communicate along the length of the Wolffian ducts adjacent to the pelvic kidneys (character 1, state 1) evolved either once on the branch leading to all salamanders, excluding the Sirenidae (with secondary loss in the Proteidae; character 1, state 0), or evolved independently on the branches leading to the Cryptobranchidae + Hynobiidae and the Salamandroidea excluding the Proteidae.
However, collecting ducts that do not communicate with the Wolffian ducts along their lengths traveling adjacent to the pelvic kidney (character 1, state 1) were recovered as the ancestral state for the Cryptobranchidae + Hynobiidae and all other salamander excluding the Proteidae and Sirenidae.
The Cryptobranchidae + Hynobiidae, Ambystomatidae Dicamptodontidae + Salamandridae, and Proteidae lineages possess a Bidder's duct, while this characteristic is lacking on the branches leading to the Sirenidae and Amphiumidae + Plethodontidae + Rhyacotritonidae.