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Pemphigus populitransversus, gall on cottonwood - Pemphigus populitransversus

Pemphigus populitransversus, gall on cottonwood - Pemphigus populitransversus
Plymouth Rock, Winneshiek County, Iowa, USA
October 18, 2009
Collected 11-Oct-2009

Moved from Pemphigus populicaulis. Now this one I'd be comfortable calling Pemphigus populitransversus: an oval gall with a transverse slit, not touching the leaf blade, and on an aspen leaf. P. populicaulis galls are more irregularly shaped, have an oblique opening, and are at the base of cottonwood leaf blades. I wonder if the one in your other image could be an atypically placed P. populitransversus gall?

I showed this to John Pearson, botanist, and it is a cottonwood leaf not an aspen. Does that change things?

I don't think so.
Whereas Pemphigus populicaulis apparently is only found on cottonwoods, Felt doesn't specify a host for Pemphigus populitransversus beyond the genus Populus, which includes both cottonwoods and aspens. I've never found this species on a cottonwood leaf, but this gall looks just like the ones I've found on aspen leaves.

uh oh
It looks as if I have 2 different Pemphigus galls in the same container, so there is no way to know which gall the aphids that emerged are associated with. Perhaps since the galls are both Pemphigus I can move the insects to family level and leave the galls separate. What say you?

I'd unlink the aphids from the gall and move them to genus level, with thumbnails linking to both of the galls that were in the container.

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