So it occured to me while reading this quote that he was probably not speaking of chimpanzees, Gorillas or Orang-Utans. So what apes would he have known and where these animals so prominent that that one could use them in writing?
The Modern Greek πίθηκος (píthikos) covers both monkeys and apes. Given that monkeys live closer to the ancient Greek world than apes, it is very probably that the Ancient Greek word πίθηκος (píthēkos) originally referred to monkeys, and later expanded to include apes.
The closest monkeys to the ancient Greeks would have been the Barbary macaque of North Africa. Note that this monkey is commonly called the "Barbary ape" - a leftover of the common lumping together of monkeys and apes in one category. The next closest monkey populations are in the Horn of Africa and India, and the ancient Greek world knew about these African monkeys via Egypt, even if not through direct experience, and may have known of Indian monkeys as well.
It's rarely possible to be able to identify examples in art as to species. Often, it isn't even possible to be sure whether it's an ape or a monkey (tails can easily be broken off, or might not be visible depending on the posture of the animal. The most common origin of monkey art from the ancient Mediterranean appears to be Egypt. To give a few examples:
but there are Greek examples too:
Greek or Etruscan: https://www.metmuseum.org/art/collection/search/246271
Greek or Cypriot: https://www.metmuseum.org/art/collection/search/239954
https://commons.wikimedia.org/wiki/File:Monkey-shaped_Perfume_Flask,_about_580-550_BC,_East_Greek,ceramic-Cleveland_Museum_of_Art-_DSC08202.JPG
and also from elsewhere in the Mediterranean world:
Cypriot: https://www.metmuseum.org/art/collection/search/241200
Phoenician or Assyrian: https://www.metmuseum.org/art/collection/search/325089
Finally, there are the spectacular Minoan monkey murals of Akrotiri, Thera (Santorini):
which, it has been suggested, might portray Indian monkeys, possibly revealing early long-distance monkey-trading.