Gymnosoma rotundatum is a parasitoid fly found in Europe and Asia.

[7] The larvae grow as parasites of shield bugs in the Pentatomidae family.

In Britain, the species is often recorded in warm dry sites, where it visits a range of open shallow flowers.

[8] British Isles, Belarus, Czech Republic, Hungary, Latvia, Lithuania, Moldova, Poland, Romania, Slovakia, Ukraine, Denmark, Albania, Andorra, Bosnia and Herzegovina, Bulgaria, Corsica, Croatia, Greece, Italy, Macedonia, Malta, Portugal, Serbia, Slovenia, Spain, Turkey, Austria, Belgium, France, Germany, Netherlands, Switzerland, Japan, South Korea, Iran, Russia, Transcaucasia, China, Japan, Taiwan.

This article related to members of the fly subfamily Phasiinae is a stub.