Last reviewed: 7 June 2023
Keys to European Gasteruption species
G. zarudnyi is included in some of these keys under the name G. phragmiticola. G. graciloides (= gracilis) is not included in any of these keys. It is listed on the 2019 checklist for Russia, but only for the far east (Primorsky and Kamchatka) and Kazakhstan.
Identifying Gasteruption jaculator and assectator
G. jaculator is not the only species in Europe in which the females have a very long ovipositor with a white tip. G. assectator is also not the only species in which the females have a short ovipositor. Those two species are the best-known and most successful of their kinds, but in almost all of Europe, there are similar species like G. caucasicum, G. tournieri, and G. undulatum which are also fairly common.
Without a good photo of the back of the head from above, G. jaculator can be indistinguishable from G. caucasicum, G. tournieri, and others. Even with good photos, it can be hard to separate from species like G. diversipes and G. opacum.
G. assectator can be very similar to G. undulatum, and even experts confuse it with G. minutum. G. assectator is extremely similar to G. boreale and G. nigritarse, which I wouldn't personally separate without looking at the ovipositor through a microscope.
European Gasteruption checklists
Fauna Europaea does not have up-to-date lists of the Gasteruption known in most territories. Some species are missing, some species are misnamed, and some species are probably wrongly included.
You may be able to find better checklists online, either for your territory or for nearby ones, though be aware that checklists can go out of date in less than a decade: e.g. this one for Britain and Ireland should now include G. erythrostomum. There are usually more Gasteruption in more southern countries, so checklists from places north of your observation are more likely to be missing species found there.
Some keys roughly describe where the species they feature are found. You can also check for newer observations of species in your territory by searching GBIF.