Presynaptically acting neur0toxic PLA2s are widespread in viper venoms, having been id'd from true vipers (ie V. ammodytes), Asian pitvipers ([?]. gramineus (the [?] simply means that I can't remember which genera its in now, I think either Protobothrops or Ovophis)), a number of different rattlesnakes and no doubt are also in Bothrops and related genera. SO, all the 'new' neurotoxic venoms (ie some populations of C. helleri) are not new or the result of hybridisation but rather have always been there, just haven't been looked at. They are structurally distinct from the presynaptic neurotoxic PLA2s from elapids so antivenom for one will have little effect on the other.