From the Super Mario Wiki
The Tail Boo is a Boo with a Tanooki tail that appear Super Mario 3D Land. Its powers were granted to it by the Super Leaves, and it can additionally attack Mario by swinging its tail like Tanooki Mario. Its tail is white and greyish, unlike Tanooki Mario and other Tanooki-tailed enemies, which have brown and black tails.
Tail Boos first appear in World 4-4. When Mario looks at one to stop it, it will perform a tail whip before closing its eyes, in the exact same way as normal Boos. They can only be defeated if Mario has touched a Star and runs into them with his invincibility, just like normal Boos. Some of them give Mario a Super Leaf or a Statue Leaf after they are defeated.
Names in other languages
||Boo à Queue
||Boo with tail