Bryan has published quite a few papers in which asian rat snakes get a mention.
This one deals with Coelognathus radiata
(which we were milking a lot of concurrently with the Ptyas)
The best one for all round coverage of the topic though (because it deals with venom-delivery as well) is his recent "Evolution Of An Arsenal" paper: http://www.venomdoc.com/downloads/2008_ ... rsenal.pdf
From memory (Bryan is obviously the best person to ask), there is no significant (although the rear tooth is ever so slightly enlarged) differentiation in the dentition of the rat snakes ie. they are not "rear-fanged", and there is certainly no grooving on their teeth (they are not "opisthoglyphous"). There are no compressor muscles either of course so I think the venom-delivery system could be described as "primitive" (in the technical, non-derogatory sense). Having said that, they are more than capable of delivering at least some venom, they have no trouble whatsoever breaking the skin (as the photo below proves
) and in the case of the Coelognathus
I think there is fair reason to believe that the venom is involved in prey capture. Ptyas
however, have evolved in a different direction.
A Coelognathus radiatus
bite (needless to say their venom is not medically significant to human bite victims):
These guys (C. radiatus
) are fun to play with too: