Interestingly enough, this word wasn’t up to the standards of Wikipedia and the article has been deleted:
A neologism for a portmanteau created by incorrectly combining a malapropism with a neologism. It is itself a portmanteau of 'malapropism' and 'portmanteau'.
"That was textuous."
Of course, it’s always possible this was a low level hoax. e.g. "It was created by webcomic creator Randall Munroe of xkcd and was deleted as being made up."
But still – isn’t it a word we could use?
http://sesquiotic.wordpress.com/2011/03/25/malamanteau/ has other examples:
“And it’s still useful – it’s by far the tidiest way to refer to words such as misunderstimate, refudiate, insinuendo, bewilderness, flustrated, ambiviolent, and misconscrewed (it up). So it has clear value as a word. It fills a gap neatly. It’s a nice malamute to add to the dog team on the linguistic sled of meaning.