I never actually thought about this, but now I'm sure skulltula is from skull and tarantula <__<.
So, I'm pretty sure the official translation should now be skull-chula, as opposter so skull-tull-er as I'd normally say it.
I don't understand why you'd say it like that, seeing as there's no vowel between the 'l' and 't', thus "skull-<b>i</b>t-a" would be wrong, secondly, you are missing out the last 'l', as in "skull-tu-<b>l</b>a" <_____<
It's skull<b>TU</b>la not skull<b>UT</b>a, just pointing that out... again