Sunday, May 15, 2016

Perlesta stoneflies -- still have to leave them at the level of genus

A little surprised by this one this morning -- not that we shouldn't be finding Perlestas (common stonefly, Perlidae) at this time of year -- this is when we normally see them (May, June, July), but I was in a small mountain stream.  Don't see many Perlids in this type of stream other than Eccoptura xanthenses.  That means that there are Perlestas in most (all?) of the streams that I visit, from these small, first order streams, to medium streams like the Doyles and Buck Mt. Creek, to our large river, the Rivanna.

While most Perlids are multivoltine (life cycle of 2-3 years), Perlesta is not.  It matures, hatches, and mates within the space of a year (univoltine).  And, unfortunately, we're still in the dark on the question of species ID.  As I've mentioned before, Steve Beaty published online a revised version (4.1) of "The Plecoptera of North Carolina" just last year in December.  But his advise on Perlesta remains the same: "LEAVE AT GENUS".  (p.48)  He lists the names of 13 different species but notes that "most of [these] are currently undescribed in the immature stage." (p. 49)  So we wait.  I have no doubt that the species that I found today is not the same as those that I find in the Rivanna.

I had high hopes of finding some new Isoperlas today, but all that I saw was I. holochlora.  Maybe tomorrow at Entry Run up in Greene County.


Just two other pics from today.  A fairly mature Ameletid: Ameletus cryptostimulus.  (There were a lot of them.)

And a small Leucrocuta flatheaded mayfly, the one that I think is Leucrocuta juno (see the entry of 5/27/15).   Regret that the tails aren't fully intact.

This too, is a species I only see in first order streams.

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