An online friend had uploaded the picture on his server. I am not sure whether he knows the original source and have not been able to ask yet; if someone knows, thank you a lot! The IQDB did not recognize the image.

Riddle solved, parenting and tagging done accordingly. I am feeling a bit stupid now, but... the IQDB does not help in cases like this. Next time, I will be more careful comparing the filename with possible information sources.