I think Mac means son of in scotish/irish gaelic so "McSurname" would be in English "surnameson" or "surnameS" and in Spanish it could be "de Surname" or "SurnameZ" or SurnameS". EG: Martin would be:
Irish/Scotish: Mc Martin/ O'Martin
English: Martinson/ Martins
Spanish: De MartÃn/ Martinez/ Martines
There is actually a Spanish name which is cayo, that comes from latin Caius, so the translation could be:
McCAY=DE CAYO or CAYEZ
May 02, 2009 Rating
... by: Anonymous
I don't think any surname starting with Mc has an equivalent in Spanish
