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Parasitoid wasp - Rileya - female

Parasitoid wasp - Rileya - Female
Mansfield, Richland County, Ohio, USA
August 29, 2015
Size: 1-2 millimeters
This tiny wasp was found while dissecting the gall of a midge, Asphondylia rudbeckiaeconspicua, which attacks Green-headed Coneflower, Rudbeckia laciniata. The wasps - 5 of 6 galls examined hosted them - were deep within the gall. A guild of three parasitoid wasps are known to inhabit this type of gall: Rileya americana, Torymus advenus, and another species of Torymus (ID uncertain). Info/photos of these parasitoids is hard to come by - does anyone know which species this wasp may be? Or is it something altogether different? Thanks in advance for any help!

Images of this individual: tag all
Parasitoid wasp - Rileya - female Parasitoid wasp - Rileya Parasitoid wasp - Rileya

Moved from ID Request.

Eurytomid (female)…
Like torymids, many eurytomids are also known parasitoids of gall midges. There is a species mentioned in the literature (Rileya americana) that is associated with the specific host midge that you mention; however, I have not found any images available to confirm this. There certainly may be other associations that are not currently known.

See reference here.

Thanks Ross. Yes, I found a 1994 paper that cites the known parasitoid wasps of this gall, as noted in my description accompanying this submission. Rileya americana is one of them, but I can find no photographs to try and see if that might be a match for my images.

I just emailed Dr. Grissell, who is a world-class expert on eurytomids and torymids for his comments on these images. Will let you know his reply.

Excellent - thanks Ross
I appreciate your efforts, and look forward to what Dr. Grissell might have to say.

Dr. Grissell's response…
"Although it is a Rileya, I couldn't put a species name on it. Rileya americana was synonymized under Rileya insularis by Michael Gates in 2008. So americana would be wrong under any circumstances. Wish I could help you out better, but these wasps are difficult enough to identify when you can see them physically! Images are a bit more difficult".

Nice work and images, Jim, as I'm sure they helped in the determination.

A new genus page (Eurytomidae>Rileyinae>Rileya Ashmead 1888) can be created for this wasp.

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