WW wrote:

"It should be used if there is reason to recognise as a separate genus the group of species for which it is the oldest available name. At present, that depends on whether Pseudechis sensu Cogger is monophyletic."



Me:

Actually, what WW meant was that whether Cannia is recognizable as a valid genus will depend on whether Pseudechis is paraphyletic or not. If it is paraphyletic, then the species in Cannia would need to be transferred back to Pseudechis, or else Pseudechis would need to be splintered into as many pieces as neccessary to eliminate paraphyly. In the case of the green tree python, Kluge thought that it was necessary to include Chondropython viridis as a member of the genus Morelia so as not to [gasp] recognize a paraphyletic Morelia. In the case of the ratsnakes and their descendants, Utiger et al. took the opposite tact. Instead of invalidating Lampropeltis, Pituophis, Arizona, Bogertophis, Cemophora, Stilosoma and Rhinocheilus and transferring all the species within these genera back to Elaphe in order to eliminate paraphyly, they instead splintered Elaphe into a dozen or so genera (which are morphologically indistinguishable from one another) to eliminate paraphyly instead.



The cladists' ideological intolerance of paraphyletic taxa therefore would result in wholesale taxonomic changes no matter which extreme option they exercise. And the cladists are straightjacketed by their own ideology to either split excessively or lump excessively to eliminate paraphyletic taxa.



A sane alternative would be to recognize paraphyletic taxa as valid, as Charles Darwin and the Darwinians do. To an evolutionary or Darwinian systematist, it does not matter whether Pseudechis is paraphyletic or not. It only matters whether Cannia is monophyletic (or paraphyletic) and whether it is sufficiently different morphologically from Pseudechis to merit generic recognition. If Cannia is monophyletic or paraphyletic (meaning that all members share the same common ancestor even though not all descendants of the same ancestor are included) and if it is different enough from its ancestral genus, then it merits recognition as a distinct genus. The Darwinian alternative is sane and it is much less destructive taxonomically than the cladists insane intolerance of paraphyletic taxa.

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