Viable cross-progeny between C. elegans and other species?

Model Organism: Worms Scientific Discussion
1

Hi Worm friends,

Can C. elegans cross with other C. species? Can they produce viable progeny for at least one generation?
Has anyone used the recently discovered sister species C. inopinata? Can you mate C. elegans with them?

Thanks!

2

So far as I know, there are no known species that produce viable cross-progeny with C. elegans. This apparently includes C. inopinata:

Mating tests between C. elegans and C. sp. 34 yielded no viable progeny (Document S2).