The Arbolean were a species.
Zelopan disguised himself as an Arbolean. Tom Daley thought they looked like a humanoid/plant hybrid. (PROSE: The Golden Hendecahedron)
Behind the scenes[]
Throughout The Golden Hendecahedron several references to The Leisure Hive were made. The Arbolean are described to be similar to the Argolin, with Zelopan being described as having "light-green" skin with "yellow and green hair" that looked like a "bulb of garlic". The Presenter is described similar to the Foamasi, a race that appeared alongside the Argolins in the Leisure Hive.