Lorelei is the name of a Siren in Germanic legends, it seems. Sirens have beautiful vioces, which lead men to their deaths. This Lorelei isn't like that.

[Said Altaria sings softly to Madoka. Light pets her before turning her attention back to Madoka.] She's a shiny Altaria. It's why she's gold, not blue. I got her from a breeder, and when she hatched, I was quite as confused as you are.