by Alex » 06 Sep 2013 19:48
The tridentate apical tergum is unique to the genus Trichrysis, atleast in northern/middle europe, which removes C. iris, Spinolia unicolor and other blue-green chrysidids. The most common species is the ubiquitous T. cyanea, but there are more species in the genus outside northern europe, I'm not sure if there's any congeners in the Netherlands - likely not?
/A