Which Beasts did Hagrid Crossbreed?

[Hillman, Lee]

No: HPFGUIDX 33828

I was talking to a young friend of mine yesterday, and he asked me two
questions about information in Fantastic Beasts. 
 
One is a theory we've heard before: that Lethifolds who consume humans turn
into Dementors.
 
The second was a very good question (with a very good answer!) that amazed
me because we've never asked it on this list before. Trust inquisitive
ten-year-olds!
 
His question was, "Which two beasts did Hagrid crossbreed to make
Blast-Ended Skrewts?"
 
And his answer was, Mackled Malaclaws and Fire Crabs.
 
I think he's definitely right about the Firecrabs, but I'm not sure what it
was about the Malaclaws that made him think they were the other creature.
Are there other creatures either mentioned in the books or from conventional
mythology that, if combined with a Fire Crab, could produce a Skrewt?
 
Gwen