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Hello all!

I am doing my thesis work on Heterodon platirhinos and have discovered something troubling. Currently I am doing some work with taxonomy and have noticed that several people consider the Madagascar Hognose Snakes (Leioheterodon) a close ally to American Heterodon sp. How is this possible? I realize that during certain key points in the earths geologic history sections of the Americas where linked with Africa and there was a possibility of Heterodon like snakes making there way into Africa. But isn’t it possible that the similarities between Leioheterodon and Heterodon are examples of convergent evolution at work? Please let me know what you think here.

Thanks a bunch!

Zac

There is no evidence whatsoever that Leioheterodon and Heterodon are in any way closely related. Heterodon belongs to the New World subfamily Xenodontinae, whereas Leioheterodon belongs to the Malagasy subfamily Pseudoxyrhophiinae. The similar snout shape is due to convergence.

The following papers on advanced snake phylogeny should help clarify this:

Kelly, C. M. R., N. P. Barker and M. H. Villet. 2003. Phylogenetics of advanced snakes (Caenophidia) based on four mitochondrial genes. Syst. Biol., 52:439-459.

Vidal, N. and S. B. Hedges. 2002. Higher-level relationships of caenophidian snakes inferred from four nuclear and mitochondrial genes. C. R. Biologies 325:987–995.

Send me an e-mail if you want a PDF of these.

Cheers,

Wolfgang
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Hi Zac

As Wolfgang pointed out, they are utterly unrelated. So much so that all the Madagascar 'colubrids' are actually 'proto-elapids' in that they sit at the base of the Elapidae tree and are much more closely related to them than to a cornsnake. The snouting is also found in various other burrowers including African Naja so nothing should be really read into this other than the shape obviously suits that niche very well as its evolved convergently a number of times.

We had a look at Leioheterodon and Heterodon venom in our latest paper (which also has a taxonomical tree showing the various relationships).

http://www.venomdoc.com/downloads/BGF_Colubroidea_RCMS.pdf

Cheers
B
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