What patronymic does a Russian bastard have?

This question popped into my mind several days ago, and hasn’t left me alone since. Being illegitimate myself, I’m always curious about what sort of traditions follow baseborn children around the globe.

Russians have three names – the given name, a patronymic, and the surname. Let’s take an individual named Anastasia Nikolaevna Romanova. Obviously Anastasia is her given name, Nikolaevna is a patronymic derived from her father’s name, and Romanova is her surname.

But what of a Russian child born illegitimate, father unknown, or possibly a sperm donor? What patronymic does this child receive? Is the mother’s name converted into some sort of matronymic? None?

Help me, Dopers!