Tuesday, September 5, 2017

Another brushlegged nymph from Buck Mt. Creek: see no reason to doubt the ID -- Isonychia georgiae

I took photos of two of these nymphs yesterday: this is the second.  The morphology this time really confirms, I think, the ID of Isonychia georgiae.

"Filamentous forecoxal gills each with single filament."

Yes.  "Abdominal sterna with markings similar to any of Figs. 2.386-2.389."  Figure 2.388 looks something like this.  (.°.)  In the middle of the sterna there are what look like parentheses marks.  Above and between those marks there is a small pale circle, while in-between those marks at the bottom there are two smaller pale dots.  Have a look at sterna 6-8 on our nymph.

Bingo!  That pattern's as clear as can be, especially on sterna 6.

Finally, "Abdominal sterna 6-8 with markings similar to any of Figs. 2.386-2.388; abdominal terga yellowish brown to dark reddish brown (with or without lighter mid-longitudinal stripe)...... Isonychia georgiae."  As we've seen, we have an exact match for pattern 2.388.  I'd say the terga are dark reddish brown.

One other thing I might mention, that the gills are rosy/purplish in color is apparently also used in diagnostics.  (See the comment by Roger Rohrbeck at http://bugguide.net/node/view/1387557.)

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