Saturday, December 28, 2013
The Uenoid "continuum" in our streams and revisions to our EPT list
I have just made three changes to the Uenoid section of the EPT list I posted on 9/8/12. I have removed Neophylax atlanta and Neophylax concinnus, but I've added Neophylax fuscus. These changes were made for the following reasons.
1) I am now certain that the Uenoids I found yesterday at Buck Mt. Creek were Neophylax fuscus. I had one further thing that had to be checked: the spines on the anterior edge of the pronotum. Beaty's description of N. fuscus: "large blade-like spines on anterior pronotum" ("The Trichoptera of North Carolina," p. 87). Here is a photo that I just took this morning.
No question about it. That's a Neophylax fuscus Uenoid at the top of the page.
2) I have re-examined the larvae I found on 2/7/13 at the Doyles River that I thought were Neophylax concinnus. They weren't. They too were Neophylax fuscus; they look exactly like the larvae I found yesterday.
And 3) I am now quite sure that the Uenoids I found at the Rapidan River on 12/16 were Neophylax consimilis not Neophylax atlanta. Steven Beaty has told me that N. atlanta is extremely rare and only found in small headwater streams: he himself has never seen one. Of greater importance, you'll recall that I removed N. consimilis from consideration for the ID since the larvae I found did not have heads with a "stripe or pale area which is less than 1/2 head length" (Beaty, p. 86). I failed to note Beaty's full description: "head and legs dark brown or with stripe or pale area which is less than 1/2 head length." Vineyard, et.al. simply say this: "Head relatively uniform in colour, somewhat darker than nota or legs" (p. 45 or The Caddisfly Genus Neophylax), they make no mention at all of a pale stripe on the head. And the only Uenoid species I found last year at the Rapidan River was N. consimilis, so I'm now pretty sure that that's what I found on 12/16 as well.
That means that, to date, I have found five Uenoid species in local streams.
1. Neophylax aniqua
2. Neophylax mitchelli
3. Neophylax consimilis
4. Neophylax oligius
5. Neophylax fuscus
That sequence, as it turns out, corresponds to the Uenoid continuum that I've noted so far in our streams. That is to say -- as you move downstream from a headwater stream to a second or third order stream, you might find Uenoids all the way down, but you'll find different species. Thus, when I go to my favorite small mountain stream in Sugar Hollow -- a first-order, headwater stream -- and go to the highest part of that stream, I find N. aniqua and N. mitchelli. When I move down that stream to a site not far from the Moormans, I find N. mitchelli and N. consimilis. When I go to the South River up in Greene county, the Rapidan in Madison County, and the upper Doyles River, all second-order streams, but streams that are still in the mountains, I find only N. consimilis. And when I go to the lower Doyles River and Buck Mt. Creek, second order streams that have moved out of the mountains and into field country, I find N. oligius and N. fuscus.
That's the continuum that I'm currently seeing. If I need to revise this, I'll let you know.
Now if Beaty comes back and tells me the larvae I found at the Rapidan River really were N. atlanta I'll have some serious adjustments to make!