`Tong et al. (2002, Acta Zoological Sinica) write in their abstract: "seven species of Elaphe form a common branch before they cluster with other genera, contrary to Dessauer's assumption of the polyphyletic origin of this genus"

I have not read Dessauer's paper, but Tong et al. have. They claim that Dessauer only assumed that Elaphe is polyphyletic.'



Dessauer's written a number of papers, as I'm sure you're aware. To which paper do Tong et al. refer? And, of course, what are their reasons to characterizing his claim of a polyphyletic Elaphe as `assumption'?



` I have read Dowling's paper. He also presents no evidence that Elaphe is polyphyletic but thinks that it may be.'



I may have to go find that paper just to check. In any case, I was hoping for something more specific than `he presents no evidence'.



`Since your library does not subscribe to this journal, you would probably have to ignore it. I have not been able to find this paper even though the library has it; it is missing from the shelf. I will not ignore it.'



We'll both have to ignore it until we know what it says. But the small number of taxa alone argues against any adequate test of the phylogenetic relationships within Elaphe sensu lato.



`Similarities in scalation, in body proportions, in hemipenial morphology and in microdermatoglyphics of the dorsal scales.'



What characters specifically? From K. Dieter-Schulz's monograph on Elaphe:

`The only existing complete work on Ratsnakes so far was undertaken by Boulenger (1894b) and was based exclusively on morphological characteristics. His definition however does not permit a separation of the genus from other colubrids, e.g. the genus Coluber.' K. Dieter-Schulz doesn't present a workable definition (it isn't his aim), which apparently leaves us without any morphological definition for the species that has been based on a comprehensive study of the genus. On scalation in particular it's worth mentioning that Lenk et al. state that groups corresponding to Rhinechis, Elaphe sensu stricto, and Zamensis were recognized prior to Boulenger's work on the basis of differences in pholidosis. On hemipenes, K. Dieter-Schulz writes that `the male copulatory organs of members of this genus are extremely variable' (p. 21).



`As I said, paraphyletic taxa may be splintered if some members of such taxa can be shown to be morphologically disparate. For example, I am open to the idea that some species may be removed from the paraphyletic Elaphe on morphological grounds.'



Then why have you stated repeatedly that splitting paraphyletic taxa is `scientifically untenable'?



`So far you have provided no evidence that Utiger et al. resurrected numerous old names on the basis of morphological disparity.'



OTOH, I have provided reference to a paper demonstrating morphological disparity among the Old World members of Elaphe sensu lato (namely, Helfenberger's 2001 paper)/ K. Dieter-Schulz is another good source. So long as the taxa are morphologically disparate, why be so concerned withi whether or not this morphological disparity was explicitly stated as the reason for the splits? Is your objection to the validity of the taxa themselves, or simply that Utiger et al. didn't make what you feel to be the appropriate nods to morphology?



Patrick Alexander

[ Show Entire Thread ]