`Molecular data of all sorts have indeed proven more useful than morphological similarities in elucidating branching order. However, it is cladistic dogma to ignore morphological disparity in classification, since Hennig rejects its use.'



I disagree. Both Kluge and Burbrink paid quite a bit of attention to morphology.



` The way Burbrink split Elaphe guttata is no different than the way Utiger et al. have splintered Elaphe; they both ignore morphological disparity and only rely on branching order only.'



Actually, Burbrink takes morphological disparity into account, and demonstrates its existence among the taxa he creates, in the splits of both guttata and obsoleta. He's just willing to accept very low amounts of morphological disparity if they agree with the cladogram.

Utiger et al. has already been addressed in this matter.



`My interpretation is different. As one can see by the two new genera they coin, there isn't any good morphological character to distinguish one genus from another since these characters are variable intragenerically or even intraspecifically.'



This is incorrect. Two characters are given that unambiguously differentiate Orthriophis and Oreophis from each other, specifically:

precaudal vertebrae 193 in Oreophis, 222-272 in Orthriophis (yes, variable intragenerically, but there is no overlap, and thus no ambiguity in the differentiation of the genera)

hemipenis cylindrical and with a basal hook for Oreophis, hemipenis biolobed and without a basal hook for Orthriophis.



`On the other hand, the taxa they recognize clearly are delimited from their consensus cladogram. Each major branch in that cladogram is classified as a different genus. That is no different than Burbrink, who classifies each major branch in his analysis as a different species.'



This is also incorrect. Though the weighted MP tree shows Zamensis as monophyletic, the consensus tree shows a polyphyletic Zamensis, with Zamensis persicus apparently unrelated to the remaining Zamensis. Apart from the very close morphological resemblance between Zamensis persicus and other Zamensis (particularly Z. lineatus and Z. longissimus, with which it was formerly considered conspecific), there doesn't appear to be a compelling reason to conclude that these taxa should be congeneric. Yet Utiger et al. conclude they are congeneric.



`It is true that there is no objective measure of morphological disparity. Darwinian taxa are indeed subjectively delimited. The alternative is far worse. The cladists, who have no guideline for delimiting taxa other than equal rank for sister taxa, are far more subjective. Kluge, for example, states that he can either recognize one, two or three genera given the particular topology of his cladogram. He finally decides that, for the sake of taxonomic efficiency, he will recognize but one genus for Charina bottae, Lichanura trivirgata and Calabaria reinhardtii. I submit that taxonomic efficiency is not an objective method for classifying organisms.'



Any taxonomist could have recognized one, two, or three genera based on the available data. It's hardly a particular fault of cladism that it allows this.



I agree, though, that `taxonomic efficiency' is a very poor justification for any classification, particularly, in this case, because no greater efficiency is gained.



`In fact, it is far more subjective than if one relies on morphological disparity.'



Kluge based his reassessment of the New World erycines entirely on morphology, though. He simply decided that the level of morphological disparity he found between Charina, Lichanaura, and Calabaria wasn't great enough to require a generic distinction. A Darwinian could have done the same.



`The first alternative of lumping all three into the same genus results in a morphologically heterogeneous taxon. The second alternative is to recognize three genera, meaning that Pan paniscus and Pan troglodytes would be classified in different genera, not very satisfactory. The third alternative is to recognize Pan and Homo as valid genera, the nearly universally accepted classification. Without any guidelines, the cladist is free to choose among any of these three equally valid alternatives. The Darwinians, however, are far more likely than not to choose the third alternative of recognizing 2 genera since they take morphological disparity into account.'



All three options are open to all taxonomists, though. I suspect that most cladists would be likely to recognize two genera, as well. I think the primary problem with Kluge's taxonomy isn't that it's cladistic, it's that it isn't very well done.



`The best alternative unfortunately, is one that is not available to the Hennigians, who are intolerant of paraphyletic taxa.'



And yet, as already discussed, an option that was available to Utiger et al. But, of course, that would've resulted in perpetuating a morphologically heterogeneous taxon.



Patrick Alexander

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