is Welsh, comes from an Old Welsh word for prince or leader (mael), and is the name of a legendary prince in the folk tale of St Dwynwen: https://secure.wikimedia.org/wikipedia/en/wiki/Dydd_Santes_Dwynwen
It's very uncommon as a modern Welsh name, quite probably because of the legend.
Artis as a surname is probably derived from Artois:
http://www.surnamedb.com/Surname/artis