Tuesday, April 22, 2014

And the answer is -- it "may" be A. internata, it may "not" be A. internata

This Acroneuria common stonefly from Sunday at Entry Run may be Acroneuria internata, but the jury is out.  That's the word from Steven Beaty.  They see this same type of Perlid in North Carolina, and they're not really sure what to call it.  At the moment they regard it as a particular form of A. abnormis, preferring to take the conservative route.   At issue, the thickness of the light colored tergal bands.  On A. internata -- you will recall -- they are "of uniform thickness"; on this nymph they are not.  The bands are thick in the middle but slightly thinner on the sides.

In the end, there is only one way to know what this is -- a uniquely patterned A. abnormis or in fact A. internata: rear one to maturity and then see what it turns into as an adult.  That's the only way we'll know the answer for certain.

I'm not sure I possess the skill set or the equipment to carry this out.  But we've now found 3 Isoperla Perlodids and this Acroneuria Perlid for which we don't know the species ID.  I might go to NC to see how the rearing is done.  Until then: this is the common stonefly (Perlid), Acroneuria sp., possibly A. abnormis, possibly A. internata.   That's where it stands.  Lots of uncertainty in the entomological world when it comes to species ID of some of our stoneflies.


Off to Oregon on Thursday -- back early next week.  If the sun shines in the West, I'll be out seeing what I can find in the streams around Portland.

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