This whole discussion is somewhat moot as a real biologist would almost always write "species of octopus", singular.

“Literally” doesn't actually mean figuratively, even in use; it's used (figuratively itself) as an intensifier applied to some other figurative expression. This actually has the opposite effect to “figuratively”, which by explicitly stating that a use is figurative acts as a qualifier, rather than an intensifier, of the figurative expression it modifies.

> What's popular isn't always correct and dictionaries by definition reflect usage.

What's popular is correct by definition, that's why dictionaries reflect usage, they don't prescribe it. Language is about communication, not syntax, people do use "literally" when they mean figuratively and you know it, I know it, so they are communicating, the word has obtained new meaning. Words are not static things.

I was walking across campus with a friend and we came upon half a dozen theoretical linguists committing unprovoked physical assault on a defenseless prescriptivist. My friend was shocked. She said: "Aren't you going to help?"

I said, "No; six should be enough."

(copypasted from http://itre.cis.upenn.edu/~myl/languagelog/archives/002938.h...)

Adam Ruins Everything had a episode that covered this: https://www.youtube.com/watch?v=fu5XDrdD7KM

In short: The dictionary isn't the "law", it lags behind the language as it is actually used. Once the "reverse" definition of "literally" became common in usage it became the new definition - not what a dictionary used to define it as.

What's the point of being "correct" if nobody understands you?