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Seeing psammophis being considered closer to elapids than colubrids was a bit of a surprise to me. Not for any academic reason, as I'm a layperson, but because everything I've read on them has them conventionally listed as colubrids. I've never even seen this questioned before. Branch shows some of the species of psammophis as being dangerous in the "Snakes of Southern Africa" field guide, but doesn't get into the elapid/colubrid discussion as I recall.

What characteristics tend to relate the genera to elapids more strongly that to colubrids?

Are there other colubrid genera that this may potentially apply to as well, and specifically I'm wondering about hydrodynastes and philodryas. Hydrodynastes already looks quite elapid-like so it doesn't seem to be a stretch.

Actually that was a firecracker compared to what we have coming out.

In any case, the advanced snakes (Colubroidea) are a very diverse group. Psammophiinae (which we took to calling 'protoelapids' as a very casual term) are most closely related to the Atractaspidae (stilleto snakes and such) and the Pseudoxyrhophiinae (which is made up by all the Madagascar advanced snakes, such as Leioheterodon). After that, the nearest neighbors (and still very close) are the Elapidae. on the other side of the Elapidae are the other 'colubrids' and there are several distint lineages there as well, including the Colubrinae, Homolapsinae, Natricinae, Xenodontinae and others.

The Xenodontinae lineage is a mixed bag. Heterodon and Hydrodynastes would typically cause mostly just localised swelling but I wouldn't really peg them for much more. In contrast are the Philodryas species (which are also Xenodontinae) which are well documented to have severe bites.

Sitting as a very basal split at the absolute bottom of the Colubroidea tree are the Viperidae.

This is all stuff thats already known. Our venom results are going to cause a pretty big seismic shift. The first two papers will be out sometime in July and the third in August. I'll of course post when they're out.

Cheers
BGF