Metulio is from Metulius, which was the name of one of the men that killed Julius Caesar
. Often is used Metellus, but i found a reliable source saying his real name is Lucius
Metulius Cimber. Metulius only gives two results at Google.com, so i tried Medulius, which came back with lots more. Medulius means 'a person of the Medulii tribe' (Medulii is plural and Medulius is singular). The Medulii tribe were Celtic and lived near Médoc, a place in nowadays France
(then it was called Gaul). The Latin name of Médoc is Meduli Litus
meaning 'land of the Medulii'. I couldn't find the meaning of the tribe's name itself, though.