There aren't any vermin as options though, which is the weird part. A fiendish Large Monstrous Spider/Sword Spider is a Magical Beast due the template changing their type, meaning that everything either has the Magical Beast type or the Outsider type. The sidebar specifies Vermin gaining hit die, which doesn't make sense, as there's no vermin option.

Also random side note - If a creature loses the Mindless quality (due to the Int gains) does it retroactively gain Feats/Skills, or do only new HD give it Feats/Skills? I'm reading Ur-Priests Monstrous Handbook right now, but I can't find an answer to the question.