A copy editor asked me if I wanted to change the title of my article "Was Lorca a Poetic Thinker?" to "Was García Lorca a Poetic Thinker?" or "Was Federico García Lorca a Poetic Thinker?" I said no. I didn't title my book "Apocryphal García Lorca." That would have sounded awful. My next book is not going to be "What García Lorca Knew." Rhythmically, those titles just don't sound right to me.
It's complicated, because Lorca and Galdós are unique in being known primarily by their maternal surnames. Not quite unique, because I've heard Biedma for Gil de Biedma. It is wrong to say Gassett for Ortega y Gassett, but it's fine to say Ortega. It's wrong to say Márquez for García Márquez, or Llosa for Vargas Llosa, but you can't say "García" for García Márquez or "Pérez" for "Pérez Galdós."
Anyway, I think I was right to stick to my prosodic instinct in this case.