Where to modify the pseudonym used to rate Android apps?

I am currently rating android applications that I downloaded with the username firstname.lastname where firstname and lastname are mine. However, I would like to put a pseudonym on it because my real name reveals to everybody the device I am using, which should be private. Currently, my rating looks like this one: firstname.lastname on May 22, 2012 (Samsung Galaxy S2 with version 1.0) I looked into my public profile of Google+, but I cannot find something which looks like firstname.lastname. I looked on the Google Play website, but I did not find related preferences. Where can I change this name? Is it in the device itself or what?