Thursday, October 5, 2017

And yes, it was Pycnopsyche luculenta

On 7/10 I established the ID of a Pycnopsyche casemaker that, in the past, I had misidentified as P. scabripennis.   As it turns out it was P. luculenta.  I also suggested that the larva in the photo above was probably the very same thing, but it was no longer in my collection for me to confirm that conclusion.  Well, lo and behold,  I came across a vial yesterday in which this larva had been preserved.  It was in one of my large vials: the case of this larva was one of the longest I've ever seen, 58mm (2.3 inches).   Found on 5/6/12.

I've now examined the larva, and it was indeed Pycnopsyche luculenta.   Back to our key (Larvae of the Southeastern USA: Mayfly, Stonefly, and Caddisfly Species), pp. 394-397.

229  ...dorsal spacing hump on abdominal segment I absent or reduced to remnant occupying no more than about 1/8 of dorsal view: case cylindrical, constructed only of stones....230

229' ... dorsal spacing hump on abdominal segment I present and of normal size, occupying 1/4 of dorsal view (often collapsed, deflated, or retracted, evident only as a wrinkle or pucker); case cylindrical or depressed, constructed of plant materials or of sand or stones and often with plant materials.....231

The dorsal hump is very clear on this larva.

On to couplet 231.

231  Ventral margin of each hind femur with 3 or more major setae....232
231' Ventral margin of each hind femur usually with 2 major setae....233

Ours has 3-6 major setae.

232  Abdominal sternum I with 12-17 anterior (sa1) setae (mostly very small), 6-7 setae on each posteromesal (sa2) sclerite, and 6-8 setae on each lateral (sa3) sclerite; case circular in cross section and composed of quadrate plant parts; possibly cool springs or streams at higher elevations. ... Pycnopsyche divergens

232' Abdominal sternum I with 3-11 anterior (sa1) setae (mostly very small), 3-6 setae on each posteromesal (sa2) sclerite, and 2-6 setae on each lateral (sa3) sclerite; case depressed in cross section and with 1 or more long sticks along sides; streams ... Pycnopsyche luculenta (or P. sonso or P. pani, both in high elevation streams)

Our case is clearly that described in 232'.  What about all of those setae?  I see about 10 setae at the sa1 position; 3 on each of the sa2 sclerites (sorry, I know they don't show up clearly in my photos), and 3 on each of the lateral (sa3) sclerites.

So, luculenta, sonso or pani?  I have to go with P. luculenta.  This larva, like the other one noted in my previous posting, was found at relatively low elevation (500-600' ABSL) in a very small stream, this one, a tributary of the Moormans River.


One final note,  the other larva that I thought could be P. luculenta, this one,

with a similar case, turned out to be P. scabripennis (only 2 major setae on the hind femora).  It was in a fair sized river (the Rapidan) where, to date, P. scabripennis is the only Limnephilid I've found.

No comments:

Post a Comment