At the moment there are eight recognized species within this genus. There is, however, still a lot unclear about the taxonomy of these animals. An example of this are the species complexes. We consider T. verrucosus a complex of multiple species/subspecies, because there are significant differences in morphology and behavior between the different morphological forms.

There probably are more undiscovered species and populations of crocodile salamanders out there. In Vietnam for example a new species was discovered a few years ago, which has recently been described as T. vietnamensis.

On the right you can find the currently recognized Tylototriton species with information concerning their ecology, behavior, distribution and morphology.
 

Echinotriton species
The genus Echinotriton (Nussbaum & Brodie 1982) consists of two species: E. chinhaiensis, occurring in Zhejiang of China (Cai & Fei 1984) and E. andersoni, endemic to five islands of the Ryukyu archipelago, Japan (Nussbaum & Brodie 1982; Nussbaum, Brodie  & Yang 1995). These highly limited distributions make these species very vulnerable to habitat loss and other threats.

Echinotriton is unique among amphibian genera in having an anteriorly curved spine on the posterolateral surface of each quadrate. Echinotriton is most similar to Tylototriton, but differs in a number of significant morphological and life history features. The ribs of Echinotriton are free of muscular attachment distally, sharp-tipped, and often penetrate the skin through the primary warts. Furthermore Echinotriton has a stockier body than Tylototriton, with shorter limbs, digits and tail (Nussbaum & Brodie  1982). Echinotriton also display very different behaviour as compared to Tylototriton: whereas Tylototriton reproduce during an aquatic period, Echinotriton remain completely terrestrial and deposit their eggs on land, the larvae are washed into water bodies where they develop. These two species are an interesting subject to study the geographic history of the isolation between the Ryukyu archipelago and the mainland of Eastern Asia.

Paramesotriton species
Wart Newts (Paramesotriton sp.) are almost completely aquatic newts from China, Vietnam and Laos. Some species occasionally leave the water outside the breeding season such as P. deloustali (Rehak 2002), but P. caudopuncatus seems to be aquatic during the whole year. Juveniles spend time on land after metamporphosis (Rehak 2002; G. Espallargas comm.) As can be concluded from their name, they have a particularly warty skin. Dorsally the species are mostly dull colored, but on the underside a pattern of yellow to red spots is present.

Two aspects of this genus are still almost completely unknown; the natural biology and taxonomy. No year round- or population studies have been done on Paramesotriton species. On taxonomic level, there is still much to discover. The most striking species of the genus, Paramesotriton laoensis was only described in 2002. To show the present uncertainties within the genus, a phylogenetic tree is shown below. Several separate evolutionary lineages can be identified, two of those in Vietnam (Paramesotriton sp. from Cao Bang, related to P. fuzhongensis, and Paramesotriton sp. from Bac Kan, related to P. deloustali). As can be seen in the tree, several cryptic lineages exist, which represent likely future species/subspecies.

Also striking is the position of P. laoensis. This, together with morphological traits shared with Pachytriton, created the opinion that P. laoensis is in fact not a Paramesotriton, and should be placed in its own new genus (Weisrock et al. 2006).

E. andersoni
 
E. chinhaiensis

P. caudopunctatus

P. chinensis

P. deloustali

P. fuzhongensis

P. guanxiensis

P. hongkongensis

P. laoensis