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3. Psychomyiidae

This is not a Philopotamid. It is Psychomyiidae and it looks like Lype sp. but it is hard to see the sclerites on the mentum. It would be easy to ID with a close-up of the anal claws and ventral side of the head. Lype does not have long ventral teeth on the claws like Psychomyia sp., ventral teeth on the anal claws, that is.

You know how sometimes you just want to unsend an email... I could be wrong on this ID. In fact, after reinspection, I'm leaning more toward Philopotamidae. Without being able to see a hatchet-shaped foretrochantin (Psychomyidae) you can't definitively ID even to family. The way the fleshy mesonotum overlaps the dark posterior margin of the pronotum, along with the apparent lack of T-shaped labrum, led me to suspect a Psychomyid (but occasionally you can see this with Philopotamids, too). The head shape also appears to be more consistent with Psychomyidae, but now I suspect that it may be the angle of the shot. You definitely can't see the venter of the anal claws clearly or a clear view of the mental schlerites, so I don't think we can be confident about labeling the genus of this photo set. Heck, the family may even be wrong. My statement that it looks like Lype wasn't based on specific diagnostic characteristics, and I didn't mean for it to be taken as a definite ID. Sorry for any confusion.

Given a real specimine, the ID would be immediately obvious, but based on these photos, I'm not at all confident of the correct ID.

Again, sorry for the confusion.

-Matt

Folks - just got back to looking through the taxonomy discussions and I don't think this is a psychomyiid. The forelegs are too long. In general all the legs are too long for psychomyiids - in particular the femur is long and appears nearly circular in cross section. They are usually much shorter and laterally compressed in the psychomyiids.

But just because we know what it is not doesn't mean we know what it is. Very few of the larval polycentropid species have been associated so any guesses based on these photos are just that. I guess Nyctiophylax. That is based almost solely on what we can see of the anal leg and claw. The claw appears to be a more smoothly curved arc than any of the polycentropids I have seen.

I want to thank Jason for putting up these great photos. They are a real test for all of us and our knowledge of the critters, not just a key. And on a selfish note, they are great practice for the "stump the chump" stuff I get involved in. For the readers who are going to the North American Benthological Society meeting the end of the month bring your unknown critters and stop by the Taxonomy Fair - you can find alot of chumps there who enjoy a good challenge - or just talking critters.

dave

OK, then, I'm moving this one all the way up to "Trichoptera" and not giving it a family ID.

Have fun at NABS. I'm not going this year, but my advisor and a couple of my labmates are.

You mean you are not willing to go at least to family based on a hunch?

dave

Half the IDs on this site are based on hunches. I just got confused after reading through this thread as to which hunch pointed where. I'll call it a Polycentropid for now if you want.

Hey guys-

What is a Polycentropid? Do you mean Polycentropodid? Isn't that what a member of family Polycentropodidae is called?

Roger - thanks for catching the typo. We haven't heard back from Matt to see if we are approaching any degree of consensus on our hunches.

dave

Jason & Dave,

Jason - Can you remember the water type you collected this specimen from? It seems this would have a lot of bearing on sorting this out and it wasn't discussed for some reason. I believe tumbling little brooks and cobble headwaters are the preferred habitat of Philopotamidae (Finger-net Caddis) whose nets are better adapted to moving water. The polycentropodids (Trumpet-net Caddis) are better adapted to stillwaters. They are mostly pond fauna out here. Their nets are so dense they look like cases and are not well adapted to moving water. I wouldn't think you'd find them with hydropsychids.

Dave - Between questions about habitat and from what I can see in the photo, I'm taxonomically vexed. The specimen looked more like a philopotamid to me at first glance as I thought polycentropodids usually had spotted head capsules (at least the ones I've seen in the West) and their pronotums usually tapered from front to back. I was puzzled by your dismissal of philo without a mention when suggesting poly, especially after explaining why it wasn’t a psychomyiid. At first I thought perhaps you made a typo. Then I enlarged the photo and noticed I couldn't find the flat-edged scraper, and I think I might be seeing a pointy trochantin. Hmmm... I don't think this is a psychomyiid and it should be moved to Polycentropodidae. Am I on the right track here?

This specimen came from a tumbling, cobbly little brook.

Now I'm really vexed!:)

Unless we hear something to the contrary from Dave, this specimen should be moved back to Philopotamidae (Finger Net Caddis) then. You were probably right in the first place, Jason. The T scraper could be receded and the pointy trochantin could be just an artifact in the photo I'm turning into something it isn't.