"The butterfly and the ape."

Translation: Η πεταλούδα και ο πίθηκος.

[linguista420]

Now we know why they called it “Australopithecus”.

[lfd]

What is the difference between ‘ο πίθηκος’ and ’το πιθήκι’?

[troll1995]

Πιθήκι is more likely used as an insult and not to describe the animal. Πχ Κάνει σαν πιθήκι = He is acting like a monkey! If used with the diminuitive (το πιθηκάκι) it is used to talk about the baby monkeys.

[chari288242]

μαϊμού is not possible?

[jsclingman]

What are the neuter versions of the articles?

[D_..]

Looks like you haven't read the tips for the second skill (https://www.duolingo.com/skill/el/Basics-1/tips-and-notes) and are unwilling to google it too... ;)

[jurgen_maes]

η πεταλούδα και η μαϊμού

[D_..]

Apes are not monkeys and monkeys are not apes. This also applies to the Greek terms.