Gasterruption assectator aggregaat
In the 2016 published paper by Niklas Johansson and Kees van Achterberg  the authors describe three Gasteruption species that previously were defined as the species Gasteruption assectator.
When there is a suspicion that about a species that it may actually include a number of species this is referred to as a species complex, informally also called a species aggregate .
Based on newly found morphological characters it turns out that Gasteruption assectator actually includes the following three species:
- G. assectator
- G. boreale
- G. nigritarse
The species are identified based on the following morphological characters :
|1||Width of hypostomal bridge||♀, ♂|
|2||Shape occipital carina||♀, ♂|
|3||Sculpture mesoscutum, coxae and head||♀, ♂|
|4||Colour facial hairs||♀, ♂|
|5||Hairs at tip ovipositor sheaths (dorsal view)||♀|
|6||Ratio length ovipositor sheath and tibia||♀|
|7||Shape head dorsally||♂|
In the field these characters will be difficult to identify, especially characters 1 and 2 as they are accessible ventrally and character 5 is visible under appropriate enlargement. The other characters can be accessible in principle on good and sharp photographs.
On this site a species from this group with unclear characters is for the time being categorized as ‘Gasteruption assectator agg.‘ instead of ‘Gasteruption sp.‘ to make emphasize this background.
Potential garden species (Krimpen aan den IJssel)
G. nigritarse has been found in the East and South of the Netherlands  and therefore a less likely candidate as future garden visitor here in the West.
G. boreale has been found in the vicinity and can be a potential candidate visitor.
G. assectator is present in the garden.
References1 Johansson N, Achterberg C van (2016) Revision of the Palaearctic Gasteruption assectator aggregate, with special reference to Sweden (Hymenoptera, Gasteruptiidae). ZooKeys 615: 73-94. https://doi.org/10.3897/zookeys.615.8857
2 Sigovini, Marco & Keppel, Erica & Tagliapietra, Davide. (2016). Open Nomenclature in the biodiversity era. Methods in Ecology and Evolution. 7. 1217-1225. 10.1111/2041-210X.12594.