Hi
Now that I have both
Elliptorhina sp. I wanted to ask exactly the same question!
There could be a real problem with 'dwarf hissers' because they seem to have low/no genitalia differences and identical body size could suffice....
I
guess the diverse hisser genera
inter se shouldn't be a problem because inter-genus breeding is quite unlikely even though
Gromphadorhina sp. can be crossed with
Princisia sp. but
Princisia is probably no valid genus.
Gromphadorhina and
Elliptorhina look quite different but... good that you ask!
There is at least one thread about the
Blaberus sp. hybridization problem:
Citation by Pharma (too lazy to retype,
original thread):
According to the male genitalia [LM Roth, 1969, Psyche 76,3] (and User Lucihormetica if I remember that correctly) it could/should be only possible within the same group. The Giganteus-group contains only B. giganteus and B. craniifer and there the size of the two species is too different to make a crossing likely. That means that B. craniifer hybrids are only hybrids of different local forms of B. craniifer and not species hybrids. Besides: I can't find a hybride on the link...This furthermore means that B. atropos syn. B. fusca could only possibly breed with species of the Atropos-group and for example B. colosseus only within the Brasilianus-group. Because several of the possible combinations shouldn't/couldn't work because of size and morphology differences (within the same group) or never occurred because at least one of the possible species is not in culture, any sort of species-hybrid in culture is wery unlikely. In addition: Several species have overlaping habitats and therefore it seems obvious that nature took precautions to omit hybridisation (well, there are several known animal and plant species showing fertil hybrids in such cases).
Then: Are you sure to have
B. atropos and not
B. craniifer syn. B. atropos (you in the US seem to often use
B. craniifer only for the 'Black Wings'/'Florida Keys' variety and for all other 'Death Head' varieties
B. atropos)?
Besides: In Germany they tried to interbreed several
Blaberus species for that purpose: nothing resulted from it.
The real problem with this genus seems to be interbreeding of local varieties and unclear origin.
Personally I wouldn't co-culture them and escapees (luckily unable to climb back into a box) win a free trip to Lizards Island

.