R Campbell wrote:



"OK, all that I understand, but how is it morphologically different than a solenoglyph, aside from the axis of the maxilla's movement? Mitochodrial DNA aside, and behaviour means nothing to me as a classification system, My one year old son acts like a cat, but is not feline......Not trying to start an

argument just looking for specific differences that make it morphologically unlike the other solenoglyphs...."



I don't know how catlike your son is behaving but I doubt that he has exhibited any behavior that is unique to cats. On the other hand, Atractaspis do act differently than most snakes, as Greene pointed out, and their behavior is similar to some other elapid snakes. One should not dismiss such unique similarities so casually.



That said, I believe you are looking for differences in the comparative anatomy of Atractaspis fangs and viperid fangs. According to Kate Jackson (2002): "In elapids and atractaspidids the entrance orifice and the discharge orifice are joined by a visible suture along the anterior surface of the fang. In viperids the anterior surface of the fang is generally smooth."



Their differences are not great but again, snakes in the genus Atractspis are more similar to elapids than they are to viperids. An additional difference between viperids and Atractaspis is the way they use their teeth. Snakes in the genus Atractaspis do not rotate their fang forward and open their mouth to bite, unlike viperids. Instead they move their fang laterally and ventrally so that the fang sticks out of their closed mouth and they then "envenomate prey with a unilateral backward stab of one fang projected from a closed mouth" (Deufel and Cundall 2003).



Therefore, even though Atractaspis have long fangs, unlike most elapids, their fangs are nevertheless more like those of other elapids in retaining a visible groove on the anterior surface and they are deployed differently than the solenoglyph teeth of viperids. In fact, the structure of their venom delivery system and their biting behavior seem to have evolved to conform to their elapid like biting behavior.



In order to classify Atractaspis as a colubrid or as the member of a separate family from the Elapidae, one would have to ignore all of the similarities (morphological and behavioral) between Atractaspis and (at least some) elapids and of course the mtDNA data of Heise et al., which shows Atractaspis as a member of the Elapidae. I am more convinced than ever that the Atractaspididae is a polyphyletic taxon.



Reference

Deufel, Alexandra and David Cundall 2003. Feeding in Atractaspis(Serpentes: Atractaspididae): a study in conflicting functional constraints. Zoology 106: 43–61

Jackson, Kate 2002. How Tubular Venom-Conducting Fangs Are Formed. JOURNAL OF MORPHOLOGY 252:291–297

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