Reptile & Amphibian Forums

Hello all-
I have noticed many postings regarding new world members of the Elaphe genus (corn, rat snakes, etc.) as Pantherophis genus. I would like to make this the topic of a term paper I need to write, but cannot find any sound scientific reasoning for this change. How did this taxonomic change come about, by whom & when did it happen? But most importantly, was it published in a PEER REVIEWED journal?

Thanks in advance for all of your help!!
-Byron

I've temporarly uploaded a PDF copy. The link is below.

Cheers
Bryan
Utiger ratsnake paper

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Dr. Bryan Grieg Fry
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Australian Venom Research Unit,
University of Melbourne
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Population and Evolutionary Genetics Unit,
Museum Victoria
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http://www.venomdoc.com

Thank you very much for the article! I knew someone on this forum could point me in the right direction.

The genus Pantherophis was indeed resurrected by Utiger et al., who consider these species, traditionally placed in the genus Elaphe, to merit a genus of its own. They base their conclusion primarily on mtDNA data, although they also included hemipenial morphology in their analysis. There is one big problem with their analysis: their placement of the American species Senticolis triaspis, or the green rat snake. Although considered a ratsnake by many, Senticolis triaspis does not seem to be closely related to any of the species of American Elaphe (Utiger et al.'s 'Pantherophis') according to other studies, such as those by Herndon Dowling. Utiger puts this species within the ratsnake (Elaphe) clade, even though the statistical support for this placement is very weak. The questionable placement of Senticolis thus calls into question the reliability of Utiger et al.'s analysis. Since their classification is based almost exclusively on branching order inferred from mtDNA data and hemipenial structure, the likelihood that the exclusion of hemipenial characters or a more robust reanalysis of the mtDNA data will overturn their phylogeny is high. Therefore it would be premature even for cladists who agree with the practice of classifying organisms strictly according to branching order to adopt Utiger et al.'s taxonomic proposal.

There are many who do not classify organisms according to branching order alone. For these scientists, there is thus an additional reason to reject Utiger et al.'s classificaiton even in the unlikely event that Utiger et al. has found the true historical phylogeny of this group. For many scientists, a new genus is merited only if one or more species have evolved novelties that can be used to distinguish it or them from the parental genus. For example, the genus Lampropeltis has been recognized (rightly or wrongly) as a distinct genus from its parental genus Elaphe because Lampropeltis differs from Elaphe in having smooth dorsal scales and an undivided anal plate. The genus "Pantherophis", on the other hand, cannot be distinguished morphologically from "Pseudelaphe" or from Eurasian species of Elaphe, nor can the European genera of ratsnakes erected/resurrected by Utiger et al. be distinguished from one another. Therefore it is better, according to this school of taxonomists (namely the evolutionary systematists or Darwinians), to retain the species Utiger et al. placed in Pantherophis and others within Elaphe.

To summarize, the genus Pantherophis is problematic because the data supporting its phylogenetic relationship to other ratsnakes by Utiger et al. is problematic. Additionally, Utiger et al.'s classificatory practice is also controversial, since it is a cladistic classification. Since not all biologists subscribe to cladistic ideology, Utiger et al.'s classification may also be rejected on ideological grounds by other systematists. A third objection to their proposal is taxonomic stability. Their rearrangement introduces about a dozen new/resurrected genera, which are morphologically undefinable and indistinguishable from one another, while wreaking havoc with the existing taxonomy. This reclassification simply does not do any good. It does not improve our understanding of the relationships among the ratsnakes. In fact, it only obscures the close relationships among them. Utiger et al.'s proposal should therefore be rejected.