From the Super Mario Wiki
Kleptoads are frog-like enemies who appear in Super Mario Galaxy 2. Their name may have derived from kleptomania (like Klepto's name), which is a mental illness where a person has an uncontrollable urge to steal things.
They only appear in Hightail Falls Galaxy in the "Silver Stars in Hightail Falls" mission. They are little blue frog-like creatures that jump and also burrow into the ground and appear out of a random spot similar to Gobblegut. Sometimes, they have a type of item above their heads and try to keep it by jumping. When an item is on the ground, they might pick up the item and try to keep it. Also, if one gets defeated, another tries to pick the treasure up. They can be destroyed by having Yoshi eat them or jumping on top of them.
Names in other languages
|Nigēro (from "nige(ru)", to escape, and "kero", frog)
||From croa cry of a frog and Crapule (Villain)
||From "marrano", an old-fashioned name for criminals; and "rana", frog