Last name Yldefonso (Yldefonso 
) , in the entire world, is a rare cognomen. The family name Yldefonso is habitual in Latin America and the Caribbean, particularly Peru, where it is a rare surname, Mexico, and Venezuela. Likewise, Yldefonso is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Yldefonso | Argentina, Peru, Mexico, Venezuela, Philippines |
|
teofilo yldefonso Filipino swimmer (1902-1942), PH (b. 1903) |
|
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ángel yldefonso narro Peruvian politician, PE |
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