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eupelmid - Brasema - female

eupelmid - Brasema - Female
Rockville, Montgomery County, Maryland, USA
August 1, 2020
Size: body 3.3mm
If I've done this correctly, this one keys out to Eupelminae and then to Brasema using Gibson's keys (1)(2).

One area for concern is the wedge-like shape of the thorax in lateral view. This is unlike the guide's photos of this genus with the exception of this one. I suspect that this is a postmortem artifact rather than the actual shape in the living wasp but would appreciate some expert input


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eupelmid - Brasema - female eupelmid - Brasema - female eupelmid - Brasema - female eupelmid - Brasema - female eupelmid - Brasema - female eupelmid - Brasema - female eupelmid - Brasema - female eupelmid - Brasema - female

Moved from Eupelmidae.

ID kindly confirmed by Dr. Gary Gibson via email. He also confirmed that this female is in "full jump mode"

He also added "Female eupelines have a highy derived skeletomusculature evolved for improved jumping in which huge indirect rather than direct muscles are used for jumping. The arched mesonotum is part of the system, as is the middle legs stretched straight forward with the mesocoxae actually fully luxated anteriorly out of their fossa. Because of the force with which females jump they tend to tumble on landing, for which they have been called the 'back-rolling wonders', and the hypothesis is that the middle legs stretch anteriorly during a jump to protect the head and antennae during landing, much as we extend our arms if we fall." (quoted with the permission of Dr. Gibson)

Moved from Chalcid Wasps.

You are quite right about the family of course.
I am by no means an expert on eupelmids, so I typically need to see specimens in person (instead of relying on images) to ID things further. That said, the subfamily Eupelminae and genus Brasema tend to be the most common eupelmids found here, so you certainly may be correct. I believe the wedge shape in the lateral view of the thorax is an artifact of the position of the legs - reflecting whether the insect is in a resting position, or a jumping one.

I'm glad it didn't die in the full "ready to jump" posture. That probably would have at least doubled the number of images required for the dorsal stacks. These were bad enough


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