Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.

the channel catfish (scientific name:"ictalurus punctatus"), also called the channel cat, is a species of catfish.
channel catfish

the arrondissement of auxerre is an arrondissement of france.
arrondissement of auxerre

antillesoma antillarum is the only species of peanut worms (sipuncula) of the genus "antillesoma".

antillesoma antillarum