In Harry Potter and the the Chamber of Secrets, what species is Aragog?

In Harry Potter and the Chamber of Secrets, Aragog is an Acromantula.

Aragog is the enormous spider living in the Forbidden Forest. Hagrid raised him when he was young, but Aragog was later blamed for attacks connected with the Chamber of Secrets and was removed from Hogwarts. Harry and Ron find him while investigating the mystery surrounding the Chamber.

Acromantulas are giant, intelligent spiders in the wizarding world. Aragog can speak, understands human language, and commands a large colony of spiders. His family nevertheless refuses to identify the true monster because they fear it.

The film’s giant spiders are sometimes casually called “tarantulas,” but that is not the canonical species name. The Chamber’s actual monster is a basilisk, not an Acromantula; Aragog’s testimony helps Harry understand that the spiders fled from a creature they feared.