`So, in your opinion, he will ignore morphological disparity if it does not jive with his cladogram? That is still ignoring morphological disparity to me.'



Not at all. He appears to've gone to quite a bit of trouble to demonstrate that statistically significant morphological disparity exists between the taxa he created. It's just that the morphological disparity, statistically significant or not, is pretty minor. My impression (not being as familiar with genetic data as I'd like) is that the genetic data don't support his taxa all that well, either. His problem isn't that he bases his taxa on cladist ideology, it's that he's willing to split taxa based on minor differentiation, i.e., he's a splitter.



`Does the number of vertebrae distinguish Oreophis or Orthriophis from other species of Elaphe?'



We'd need a comprehensive and accurate generic description for the other members of Elaphe to know that, I think. We don't have one. Last I checked, we didn't even have such a description for Elaphe sensu lato.



`Do the differences in hemipenial morphology, even if they are confirmed, justify the erecting (pun intended) of new genera?'



In conjunction with the genetic data and generally poor morphological (and ecological, for that matter) unity of Elaphe sensu lato, yes. Alone? Probably not.



`You are correct about Zamensis not being a major branch in their consensus cladogram. You are incorrect that Zamensis is polyphyletic. All species of Zamensis do share a common ancestor, but this ancestor, at least according to the consensus cladogram, is also ancestral to all other genera they recognize, with the exception of "Euprepiophis." You have a very peculiar definitino of polyphyletic.'



All snakes, so far as we know, share a common ancestor. Does that make all arbitrary assemblages of snake species paraphyletic? Nope. Neither Utiger et al.'s data, nor any other data of which I'm aware, support the existence of a common ancestor for Zamensis that is more closely related and/or more morphologically similar to the members of Zamensis than to other members of Elaphe sensu lato. So neither paraphylys nor monphyly are supported.



If you think I'm using a definition of polyphyly with which you disagree, present your preferred definition and we can see how well that one works in this situation.



`That is not my point though.'



You said that a problem with cladism is that its guidelines for taxon distinctions are `more subjective' than those of other taxonomic philosophies. Your support for this position was the fact that Kluge, as a cladist, could have recognized one, two, or three genera within what he called `Charina'. I pointed out that any taxonomist could have done so. This removes your support for the argument that cladism is more subjective. If the relevance was unclear earlier, hopefully it is less so now...



`It can be a factor, especially if there is little morphological disparity among taxa within a monophyletic group.'



Certainly. But I think we agree that taxonomic efficiency should not be the only factor.



`One can say that I support the recognition of a paraphyletic Elaphe partly because of taxonomic efficiency,'



IMO, taxonomic efficiency decreases when taxon are created that are not very informative about their members. The large amount of variation within Elaphe sensu lato makes the generic name fairly uninformative about its members, so taxonomic efficiency is gained by splitting it into more morphologically, ecologically, behaviourally, and genetically comprehensible units.



`but the primary reason remains the fact that there is no good reason in terms of morphological disparity to split it.'



As mentioned previously, some of the genera involved were originally (back in the 19th century) considered distinct from Elaphe on the basis of morphology.

And, of course, morphological data are not the only data, nor necessarily the most important data.



`There is no evidence that he ever considers morphological disparity in the classification of Charina, Lichanura and Calabaria. It is not present in his discussion. The only factor he considers is taxonomic efficiency. That is simply untenable.'



The clade that he calls Charina is united by morphological disparity from the other erycine snakes. His genus is, therefore, explicitly based on morphological disparity. He also apparently doesn't consider the morphological disparity within Charina to be of taxonomic significance. We both disagree with him in that, but that doesn't seem to be the result of cladism.



`If Elaphe is morphologically heterogeneous, then Utiger et al. have provided no evidence to support it.'



OTOH, if Elaphe sensu lato is morphologically homogeneous (or at least sufficiently so to warrant generic identity) I'm aware of anyone who's provided evidence to support it.



`The fact that one has to look inside the lung to distinguish Old World Elaphe from New World Elaphe is stong evidence that your argument is baseless.'



? I don't know about you, but I don't have to look inside a snake's lung to know whether it belongs to Pantherophis or Elaphe sensu stricto.



`The fact that Helfenberger, a junior author of Utiger et al., has to look inside the visceral organ for topographic differences among the species of Elaphe is further evidence that your claim of a heterogeneous Elaphe is also incorrect.'



I'd be interested in your reason for thinking that internal anatomy is not of any use in generic distinctions. Or, if this is not what you're claiming here, you'll have to make your intent clearer and tell me why the data on internal anatomy gathered by Helfenberger is not of use.



Given that internal anatomy (including hemipenes) has been used extensively in taxonomy both in snakes and in vertebrates generally, I think you'll have a hard time supporting an argument against its validity in taxonomy.



`There are some authors who, rightly or wrongly, argue that Bogertophis may not be morphologically disparate enough to warrant removal from Elaphe. That would contradict your unsupported assumption that Elaphe is a morphologically heterogeneous genus.'



1) Who are the authors you refer to?

2) Many authors (Dieter-Schulz, Helfenberger, others that came up earlier in this thread, and more that I don't recall offhand in reference to Gonyosoma, Bogertophis, and Senticolis, which do not belong to Elaphe sensu lato as it was considered to exist prior to the splits of Utiger et al. and Helfenberger) have stated that Elaphe is morphologically heterogeneous. What authors have claimed otherwise?

3) Why should an author claiming that Bogertophis should be included in Elaphe (I'm assuming sensu lato) be taken to indicate that Elaphe sensu lato is homogeneous?



Patrick Alexander

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