Someone used "memo" or "memeo" but I hardly agree either. The first is misguiding as "mem" means self, so "memo" makes people think "memo" is the noun form. "Memeo " is an unnecessary transliterated name and itself has no meaning. In an artificial and logical language we should always avoid increase the number of basic roots. So I have a suggest: according to its original meaning, the metaphor to sharing and passing away of ideas and behaviors, why we not use "kulturo-geno " or "ago-geno "? If some guy doesn't know "meme" but he can have intuitive understanding to the basic meaning at the sight of "kulturo-geno ". Could anyone suggest a good idea?
”Meme” is memeo, as far as I know. :-) I don’t agree with you on this: ”In an artificial and logical language we should always avoid increase the number of basic roots.” Esperanto is a living language, and the number of roots has been increasing since Zamenhof released it. The word geno, as you suggest in ”kulturo-geno” and ”ago-geno”, did not originally exist in Esperanto.
The word memeo is used on wikipedia. https://eo.wikipedia.org/wiki/Memeo
It does seem to be used a lot even though there is nothing official. If you don't like it, you can just called it a joke instead of a meme.