I would say there probly would be other species they could live with but i doubt you will find anyone brave enough to reccomend anything.
Some ppl say you can only safely keep 1 species of reptiles together, that obviously isnt true but it is a much safer practice.
In general there are no set rules as to what species you can keep together, there are alot of varying factors such as individual temperment, feeding response, animal size, enclosure size, eclosure decoration.... etc.
Things can also change when animals get hungry, territorial...etc.
Many species can even harm or kill there own kind.
cheers
cris