R2D2 Wasp

Size about 4mm. Found on lemon tree. Its general appearance reminds more of a bug with hardly any visible waist and a body width not changing much from top to bottom. My first thought was that it looked like the R2D2 robot with a bulky round head. I have not looked into its identification yet. I am confident that it is a wasp despite the fact that a stinger that I had seen turned out to be a backwards stretched leg. The animal looks like t is wearing white socks. Its head is so clear and well-formed, with beautiful eyes, oculi, and antennae. Long wings. This species does not resemble any other wasp species I have come across and will take some time to identify. Any suggestions appreciated. Update 19/1/2017: I found an identification. This wasp seems to have a global distribution with a similar looking picture available from Portugal http://www.diptera.info/forum/viewthread.php?thread_id=42981). Other picture records match but none of them are specified beyond genus level. ALA distribution map has only three species available for Brisbane: Anastatus benthami, Eupelmus poggioni, Anastus darwini.