A few photos from Entry Run

I drove up to Entry Run in Greene County on Tuesday.  Didn't see anything out of the ordinary, but I got some nice photos worth posting.

Above and below, brushlegged mayfly, Isonychia sp. (probably bicolor).

I still hope to find a nymph with single forecoxal gills -- not sure it's going to happen.  All of the Isonychiidae I've found so far have a "cluster of filaments" at the forecoxae, meaning I can't ID them to the level of species.  On this nymph, those gills show up in this live photo, no need to go to the microscope.

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I wasn't at all surprised to see some of our winter casemakers, a Lepidostomatidae,

and a Thremmatidae (formerly Uenoidae), Neophylax consimilis.

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And, to my surprise, I also found a spiny crawler, Ephemerella subvaria, the nymph of "many colors."

There was one odd thing about this one: the pointed tubercles on terga 5, 6, and 7 were pale colored.

I'm pretty sure that on the nymphs that I've found previously, those tubercles were all black.  Strange.  I plan to look into this.  Probably just a local variation.

Pronggilled mayfly, Neoleptophlebia assimilis: identity confirmed

On August the 7th this year, I suggested that most of the Pronggilled mayflies I've found were Neoleptophlebia assimilis (then called Paraleptophlebia assimilis).  That suggestion relied heavily on pigmentation.  On morphology, I was missing one piece of evidence: I needed to see the mandibles to be sure they weren't N. swannanoa.  I found a number of nymphs yesterday at the Doyles River (my upper site), and our identity can now be confirmed.

Let's work through our key (Larvae of the Souitheastern USA: Mayfly, Stonefly, and Caddisfly Species, pp. 140-141). 

263  Gills 2-7 forked at one-fourth or more length from base; gill trachea with distinctly pigmented branches at least in unforked region.........264

263' Gills 2-7 forked near base, usually not more than one-sixth length from base; gill trachea without distinctly pigmented lateral branches, but often with very short and faint lateral branches.......267

Here's our nymph.

(You'll recall that the former nymphs are now genus Neoleptophlebia; the latter remain Paraleptophlebia.)  We clearly move on to 264.

264  Mandibles relatively elongate, with about half length of angulate (left) mandible beyond angulate shelf.......Paraleptophlebia swannanoa

264' Mandibles not elongated as above, with less (usually much less) than half length of angulate mandible beyond angulate shelf........265

Here's what we have.

The portion above the angulate shelf is roughly 1/4 the length of the mandible.  We move on to 265.

265  Posterolateral projections present on abdominal segments 8 and 9.......Paraleptophlebia( i.e. Neoleptophlebia) assimilis  

[Note: projections on segment 8 are not well formed in young larvae.]

265' Posterolateral projections present on abdominal segment 9 only....266

Our larvae are very young.  Still you can see the projections on 8.

Species ID confirmed!  Neoleptophlebia assimilis.

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Lots of Large winter stoneflies (Taeniopteryx maura/burksi) around yesterday;

Small winter stoneflies (Allocapnia pygmaea) as well.

Apatania incerta -- Little Mountain Casemaker -- at the Doyles River this morning

It's a casemaker that I don't see very often -- Apatania incerta -- but it's one of the things I was hoping to see this morning.  Beaty describes the case as "composed of mineral particles and strongly curved, cornucopia-shaped."  ("The Trichoptera of North Carolina," p. 85)  Pretty clear in the photos I've taken. 

The genus ID goes like this.

Mesonotum with two plates; metanotal sa1 sclerites absent; arrangement of sa1 associated setae in a linear transverse row...mandibles usually with uniform scraper blades (not toothed).  (Beaty, p.85)  Works for me.

On the species he adds: "larvae 6-9 mm; head dark brown to black; nota brownish-black; anterior metanotal plates replaced by row of about 20 setae; legs yellow brown."  But I'm not sure the species detail is needed.  In our new key, incerta is the only species listed for Apatania.  (Larvae of the Southeastern USA: Mayfly, Stonefly, and Caddisfly Species, p. 294)

With a Tolerance Value of 0.6, we can expect to find it only in very good streams.  And when the case is right side up, the larva is covered with a hood.  Normally, all we can see is the legs, but in this case, the part of the head also sticks out.

Our "Green Stoneflies" (Chloroperlidae), genus Sweltsa, are Sweltsa onkos

For sometime now, based on the appearance of the adults,

my friend and I have felt strongly that our Sweltsa "green stoneflies" were Sweltsa onkos in terms of the species.  With the help of our new key -- Larvae of the Southeastern USA: Mayfly, Stonefly, and Caddisfly Species -- we can now confirm that ID.   (And yes, if the genus is Sweltsa, there is nothing "green" about either the nymphs or the adults of these Chloroperlids.)

Let me work through our key (pp. 206-208). 

72  Tibial fringe setae sparse and about half as long as median outer marginal seta......73
72' Tibial fringe setae more abundant and about as long as median outer marginal seta......77

The tibal setae is dense and long.  We move to couplet 77.

77  Longest dorsal setae on last five cercal segments about as long as 1.2- 1.5 cercal segments.......Sweltsa mediana
77' Longest dorsal setae on last five cercal segments about as long as 2 cercal segments........78

I'd go with 77'.  Certainly the longest setae on at least the last three segments are close to being the length of 2 cercal segments.

78  Abdominal terga dark brown, occiput about as dark as frons; meso- and metanota rather densely covered with long dark clothing hairs.......Sweltsa onkos
78' Abdominal terga pale brown, occiput almost entirely pale; meso- and metanota with sparse, brown clothing hairs.....Sweltsa naica

That's a no-brainer: Sweltsa onkos for sure. 
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As we go through the winter, I'll keep checking Sweltsa nymphs just to be sure that onkos is the only species we have in our streams.  I can certainly say that every nymph that I have preserved keys out to onkos, and the nymphs in my photos match that description as well.