Saturday, January 5, 2013

Neophylax consimilis: the Uenoids in the Rapidan River

I've been able to identify a second Uenoid caddisfly larva to the level of species (the other one being Neophylax oligius): the Uenoids (Little northern casemakers) I found yesterday at the Rapidan River were Neophylax consimilis.  In this entry I'll post the best evidence for this that I can, though the microscope photos I've taken so far are not as good as I'd like them to be.

ventral view of head:

The medial pale spot on the frontoclypeus (top part of the head) is important for identification.

Steven Beaty ("The Trichoptera of North Carolina," pp. 86-87) describes N. consimilis in the following way:

N. consimilis -- well developed clavate ventral gills on abdominal segment 1; head and legs dark brown or with stripe or pale area which is less than 1/2 head length, often there is a gradation of head coloration which blens into that of N. oligius; underside of head usually dark; spines on anterior pronotum needlelike.  Mostly a Mountain taxon.  Common. 

In private communication, he noted an additional feature: "N. consimilis has lateral gills on 2p, 3a and 4a (a=anterior; p-posterior)."

While the "pale area" is visible in the photo above, it may be clearer in this microscope photo in which we can see two pale areas: were my photo better, you could see that these two are connected, essentially forming a "stripe."  In this photo you can also see the "clavate" ventral gills on abdominal segment 1.

Clearly, those spots/stripe cover less that 1/2 of the head length -- vs. the pale stripe of N. oligius which is greater than 1/2 of that length.

N. oligius head:

I do not have a photo of the underside of the head (I did not wish to tear the head off) -- but it is indeed "dark".  I also could not get a reasonable photo of the spines on the anterior edge of the pronotum.

I do have so-so  photos of the "lateral gills."  The lateral position is marked on Uenoid larvae by a thin hairy fringe which I've pointed out in this photo.  You can also see the ventral and dorsal gills.  All of these gills are thread-like and clear in color, which makes them very difficult to see, even in a microscope view.

This may cause you eye strain (!), but if you look real hard you can make out the "lateral gills" at positions 2p, 3a, and 4a.

The lateral gills are much smaller than the ventral and dorsal gills: they are not at all easy to see.  This is one of the problems I'm having in identifying Uenoids to the level of species: the absence or presence of lateral gills, and their position, is an important factor in making species ID.

That's the best I can do.  But I feel fairly confident of this ID.  Here are more photos of our Neophylax consimilis larvae (remember that I took photos of two different larvae).

larva two:


Very satisfying.  For a more detailed description of N. consimilis, see pp. 50-52 in R.N. Vineyard,, The Caddisfly Genus Neophylax.  The authors note of this species: "This species is widely distributed in eastern North America, ranging from Cape Breton Is., Nova Scotia, south along the Appalachian Mountains into northeastern Georgia.  It is more common in the southern portions of its range." (p. 51)

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