Hi mate
Very nice snakes, the Madagascar hognosed are some of my favorites. They are utterly unrelated to the American hognosed, they are not only in a different genus (Leioheterodon vs. Heterodon) but are actually in a different snake family as well (Pseudoxyrhophiinae vs. Xenodontinae). In fact, all the Madagascar 'colubrids' belong to the Pseudoxyrhophiinae family and this family is much much more closely related to a cobra than it is to the American hognosed. We had a look at the venom of the giant madagascar hognosed (Leioheterodon madagascarensis) as well as the western hognosed (Heteron nasicus) in one of our most recent papers. If you are interested, follow the link below, go to the publications section and download the LC/MS paper. Its got a nice big taxonomical tree that shows the relative relationships.
Cheers
B
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Dr. Bryan Grieg Fry
Deputy Director
Australian Venom Research Unit
University of Melbourne
www.venomdoc.com