The toxicity of Taricha is certainly well-established [re - "tarichatoxin"]. Part of the reason for a lack of Salamandridae is that North America has only two genera and seven species of salamandrids. The reason for other species being absent from the list as well, is because that list is clearly specific to the eastern USA only [it's a Northeast PARC website]. Since the only tiger salamander in the eastern USA is the eastern tiger, and Taricha does not occur east of the Rockies, that would be why these western forms are not included. It can be very important to know the context in which data is presented.
Regarding the taxonomy - eastern tigers are not closely related to any other species. The eastern and California complexes have been isolated from all other species for a vast length of time. The Mexican and other western forms are mostly fairly recently separated from one another, with Ambystoma mavortium being a complex of species which is closely related to A.mexicanum, A.andersoni, A.dumerilii, and all the other Mexican species. Ambystoma mavortium is neither a single species, nor the same species as A.tigrinum.
