Saturday, January 2, 2016
Exploring new streams: small tributary of the Rapidan River
I'm determined this year to explore some new streams. This morning, I decided to finally look at a small mountain stream that empties into the Rapidan River right at Graves Mill. I headed upstream until I was pretty well into the mountains and found a good pull-off. It was a small stream, and sure enough, I found a lot of small mountain stream insects. Nothing new -- but I got some good pictures.
1. In the photo at the top of the page, a "roach-like stonefly," genus Tallaperla. Lots and lots of them in the leaf packs and in packs of leaves and twigs mixed. I keep hoping to find genus Viehoperla, but those nymphs have single thoracic gills: this one clearly had two.
2. A flatheaded mayfly, Maccaffertium merririvulanum.
Very clear on this nymph are the characteristic pale "V's" on terga 5 and 7-9. Can also see one on segment 4.
3. And a nice pic of the Ameletid mayfly, Ameletus cryptosimulus.
This species is not all that common. Consequently, in North Carolina, no tolerance value has yet been assigned. Again, characteristic markings show up very well on this nymph. "Each abdominal tergum with two pairs of pale spots, one submedian pair and a pair anterolateral to those." (Beaty, Walters, and Holland, "The Ephemeroptera of North Carolina, version 4.0" p. 1.) Earlier, in version 3.3 of this guide, Beaty had noted that there are "submedian curved marks on tergite 7 followed by a median spot."
And then there are the caudal filaments (tails). "Caudal filaments basally brown...with a dark brown medial band followed by a pale band and tipped finally with brown." (Beaty, Walters, and Holland.)
Also saw lots of Perlodid stoneflies -- Malirekus hastatus and Diploperla duplicata. On my list for next week, the Middle Fork, or the South Fork, of the Moormans. Looking for some new Uenoids.
Oh -- an important note. A revised version of "The Plecoptera of North Carolina" was posted on December 15. Go to: http://portal.ncdenr.org/web/wq/taxonmanual.