Monday, March 18, 2013

Wrap Up: The Uenoid Caddisfly Species that Inhabit Our Streams

According to Glenn B. Wiggins, Uenoid caddisflies are found in "North America, eastern Asia including Japan and the north-eastern Himalayas, and southern Europe," the family containing five genera.  (Glenn B. Wiggins, Larvae of the North American Caddisfly Genera (Trichoptera), 2nd edition, Toronto: University of Toronto Press, p. 413.)  Of those five genera, only one is found in our part of the country: Neophylax.

One of my goals this winter was to determine the species ID of the Uenoids that we find in local streams.  Since the Uenoid "larval" season is pretty much over -- I'm now finding lots of cases sealed at both ends and clustered together on rocks (i.e. they're pupating) -- it's time to sum up the results.

On Uenoids, Wiggins notes: "At the family level larvae are distinguished by the anteromedian emargination of the mesonotum.  They are also characterized by a wedge -- or T-shaped  ventral apotome of the head." (Wiggins, p. 413)  He adds very little to his description of the genus Neophylax: "...mesonotum with prominent anteromedian notch; case of coarse rock fragments, larger stone along each side." (Wiggins, p. 415)

There are normally three large "ballast" stones on each side of the case for Neophylax (as we see in the photo at the top of the page): the "anteromedian notch" and the "T-shaped ventral apotome" look like this.

I have identified five different Uenoid species in the streams that I explore: Neophylax oligius, Neophylax consimillis, Neophylax mitchelli, Neophylax aniqua, and Neophylax concinnus. There are probably additional species that I haven't found: I'll be looking for them next year.

To identify species of the genus Neophylax, we primarily ask three different questions.  1) Does the larva have "clavate gills" (wide at the tip, narrow at the bottom) on abdominal segment 1?  These:

2) Does the larva have a "tubercle" on the head, and if it does, what is the shape?  One type of tubercle is long, pointed, and slopes to the rear:

A second tubercle is short and blunted at the tip.

And 3) does the larva have "lateral gills," and if it does, where are they found on the abdominal segments?  They will be found along the "lateral fringe."

Some are on the posterior edges (p), others on the anterior edges (a).  They're difficult to see.  Those pointed out on this photo -- at 2p, 3a, and 4a -- are found on N. consimillis.

There are two other details that figure into identification -- color of the head and the legs, and the absence or presence of some kind of pattern on the "face" (frontoclypeus) -- but we can comment on those in relation to individual species.

One other thing -- some Uenoids live in first order streams, others in second order streams.  First order streams, or "headwater streams," lack tributaries that have water in them all year.  They also, generally speaking, flow steeply down mountainsides.  Second order streams are formed when two or more first order streams come together.  For an excellent description of "stream order," see Amanda Briney's "Stream Order: A Classification of the Rank of Streams and Rivers," at

Now let's look in greater detail at the five species we've found.

1. Neophylax oligius.  Tolerance value: 2.4.  Commonly found in second order streams (e.g. Buck Mt. Creek and the Doyles River).

The mature N. oligius larvae I've found have been 8-10 mm long with the cases about 1 mm longer.  N. oligius  larvae do have clavate gills: they do not have a tubercle on the head, and they do not have lateral gills.  But the orange stripe that runs the full length of the face is unique and gives this species away.  You can ID this species at the stream using a loupe.

2. Neophylax consimillis.  Tolerance value 0.3.  Mostly found in first order streams, but I would not be surprised to see them near the beginning of second order streams.

Larvae also in the 8-10 mm range.  N. consimillis does have clavate gills, and it does have lateral gills at positions 2p, 3a, and 4a (as noted above): it does not have a tubercle on its head -- though you might see a slight bump.  Head and legs are dark brown, though pale, reddish spots -- which merge to form a short stripe -- are often seen on the face.

3. Neophylax mitchelli.  Tolerance value: 0.0.  Only seen in first order streams.

The N. mitchellis in my collection are 6-8 mm in length.  They have a very distinct tubercle on their heads: long, thin, pointed, and it tends to slant to the rear.

Head and legs are light brown in color.

Larvae do have clavate gills but no lateral gills.

4. Neophylax aniqua.  North Carolina does not give a TV for this species.  But it is as intolerant as N. mitchelli, perhaps more so.  It is only found in first order streams and is often found with N. mitchelli.

The aniquas I've found have all been small: 4-6 mm.  N. aniqua larvae do not have clavate gills; they also lack lateral gills.  They do have a tubercle on the head which is short, stubby and semi-blunt.  The head is dark brown: color of the legs and pronotum seem to vary.

5. Neophylax concinnus.  This is a larva I've only found in Buck Mt. Creek and the Doyles River, i.e. in second order streams, the same streams in which I find N. oligius.   Size: 8-10 mm.   I do not have very good photos.

Neophylax concinnus does not have clavate gills.  Vineyard (The Caddisfly Genus Neophylax) say that "lateral gills are usually present, at least at one of the standard positions": I can make out a gill at 2p on the two specimens in my collection.

Spicules at the rear of the mesonotum are a distinguishing feature of N. concinnus, as are transverse row of spicules on the posterior of the pronotum.


That's where things stand at the moment.  But there may be more species to find in streams that I've not yet explored.  The following additional species are noted as being attested in the state of Virginia in "An Annotated List of the Caddisflies (Trichoptera) of Virginia: Part II. Families of Integripalpia," pp. 21-22 (Flint, Hoffman, and Parker, in Banisteria, Number 31, pages 3-23): N. acutus (rare), N. fuscus, N. ornatus (Blue Ridge, high elevations), N. stolus (west-central Virginia), and N. toshioi (west-central Virginia).

Next winter -- back to the hunt.
Neophylax oligius, March 14th, Whippoorwill Branch of the Mechums.  To the right -- spiny crawler mayfly, Ephemerella dorothea.

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