Looking for insects in Costa Rica

Hmm…doesn't look like an aquatic insect???  No, no.  It's a beautiful Green iguana, male, in full mating colors.  It was a big one.  Measured 8-10' if we throw in the tail.  Another look -

Just gorgeous!

But I did find some aquatic insects.  We were in Tamarindo, Costa Rica last week -- before the BIG snow storm hit the East coast -- and one of our day trips was up in the mountains, visiting Rincon de la vieja National Park (Mt. Rincon is an active volcano).  And we did find some streams.  In fact, one was a nice cold water stream, but I didn't find anything in it.

In another small stream, one in which the water was quite a bit warmer, I had better luck.  Looking through leaf packs and at the bottoms of rocks, I found a number of caddisfly larvae.

Not a good photo, but the best I could do with my regular lens.  I was quite sure that it was a fingernet caddisfly larva (Philopotamidae), but I have no way to be sure, let alone talk about genus and species.  I didn't preserve it.  It was a "National Park," after all, and I wasn't sure if that was allowed, so I didn't have any sampling gear with me.  Alas.

I have no doubt that, at another time of year -- it's summer down there -- had I gone to the right parts of the country I'd have had a ball digging through streams, finding all sorts of different genera and species.  But we were on the west coast enjoying the beach and the tropical sunshine, so it was iguanas and Howler monkeys and mangrove birds that I pursued with my camera -- and telephoto lens.  Thought some of our readers might enjoy seeing some of my photos, so here we go.
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I. Iguanas

We saw both Green iguanas and Black or "Spiny Tail" iguanas, all of them at the resort where we stayed where they were left to run free.  We've seen one of the Green ones, and here are some pictures of one of the Blacks.

II. Shore Birds in the Mangroves

and some blue jays, which in Costa Rica are crested and have longer tails than those we see in Virginia.  One in the wild,

and one that was eyeing our breakfast!

III. Coati mundis  (pr. kwati mundi), related to raccoons

One was eating (used) toilet paper!

IV.  Howler monkeys

They woke us up in the morning and scampered around in the trees for the rest of the day.

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It was a wonderful trip, some place to visit if you get the chance.  But, if I can afford to go back, it's off to the mountains and streams, and I'll be toting my sampling equipment!

Back here -- it's time to get out to the streams.  I hope to be out there next week, but it will depend on the snow and the water levels after the melt.

Exploring new streams: small tributary of the Rapidan River

I'm determined this year to explore some new streams.  This morning, I decided to finally look at a small mountain stream that empties into the Rapidan River right at Graves Mill.  I headed upstream until I was pretty well into the mountains and found a good pull-off.  It was a small stream, and sure enough, I found a lot of small mountain stream insects.  Nothing new -- but I got some good pictures.

1. In the photo at the top of the page, a "roach-like stonefly," genus Tallaperla.  Lots and lots of them in the leaf packs and in packs of leaves and twigs mixed.  I keep hoping to find genus Viehoperla, but those nymphs have single thoracic gills: this one clearly had two.

2. A flatheaded mayfly, Maccaffertium merririvulanum.

Very clear on this nymph are the characteristic pale "V's" on terga 5 and 7-9.  Can also see one on segment 4.

3.  And a nice pic of the Ameletid mayfly, Ameletus cryptosimulus.

This species is not all that common.  Consequently, in North Carolina, no tolerance value has yet been assigned.  Again, characteristic markings show up very well on this nymph.  "Each abdominal tergum with two pairs of pale spots, one submedian pair and a pair anterolateral to those."  (Beaty, Walters, and Holland, "The Ephemeroptera of North Carolina, version 4.0" p. 1.)  Earlier, in version 3.3 of this guide, Beaty had noted that there are "submedian curved marks on tergite 7 followed by a median spot."

And then there are the caudal filaments (tails).  "Caudal filaments basally brown...with a dark brown medial band followed by a pale band and tipped finally with brown." (Beaty, Walters, and Holland.)

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Also saw lots of Perlodid stoneflies -- Malirekus hastatus and Diploperla duplicata.  On my list for next week, the Middle Fork, or the South Fork, of the Moormans.  Looking for some new Uenoids.

Oh -- an important note.  A revised version of "The Plecoptera of North Carolina" was posted on December 15.  Go to:  http://portal.ncdenr.org/web/wq/taxonmanual.

It's the "rapid" Rapidan at the moment -- but I got some nice photos

Actually, it was pretty scary up there this morning.  The water was very high and very fast (see the photo below), and I had to stay close to the shore to look through the leaf packs.  Lots of pronggilled mayflies now, and a smattering of small winter stoneflies.  But I did find some insects that made for very nice photos.

The first, a Lepidostomatid.  I didn't keep it, so I can't be sure of the genus ID -- but it's probably Lepidostoma.  In any event, I couldn't resist taking some shots of that beautiful case.

Excellent photos of the adults in Ames' Caddisflies: A Guide to Eastern Species for Anglers and Other Naturalists, pp. 186-189.  I take it these hatch as the "scaly brown sedge" in March and April.  But at time of year, anglers at the Rapidan will be focussing on prolific hatches of "yellow sallies."
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And the other treasure this morning -- the "golden stones," Agnetina capitata.   Since I reviewed the species identification of A. capitata in my entry of 9/7, I'll just point out the 1) setal row on the occiput, and 2) the presence of anal gills.

I found three nymphs in the leaf packs, and since I seem to find this species in a regular way at the Rapidan River, I'm starting to wonder just how "rare" it is.  Beaty's comment: "Listed by NC Natural Heritage Program as Significantly Rare (2010)."  ("The Plecoptera of North Carolina," p. 15).

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The sunlight was great, but the water...roaring!

Surpise, surprise! Paragnetina fumosa at Buck Mt. Creek

And a very pleasant suprise.

I went to Buck Mt. Creek this morning with low expectations.  I was pretty sure that I'd see small winter stoneflies -- and I did.  I was hoping to see the common stonefly Acroneuria lycorias since this is the only place that I've seen it.  No luck with that species, but I still made out very well.

It's the common stonefly, Paragnetina fumosa.  This is only the second nymph that I've found.  The other was also at Buck Mt. Creek, on April 17, 2013 (see the entry posted that day).  That nymph was a bit more mature, but not a heck of a lot.  Still, the diagnostic features -- see below -- are more readily seen.

For the identification, I turn to Steven Beaty's "The Plecoptera of North Carolina," p. 18.  "P. fumosa -- nymphs ?? mm; frons with a pair of yellow spots lateral to the median ocellar spot, median ocellar spot often congruous with pale yellow transverse band near labrum; thoracic nota with complex and extensive pattern of yellow markings; yellow femora with one sometimes two distinctive dark brown transverse bands; abdominal terga 3-4, 5 with a pair of pale markings and 8 and 9 mostly pale; anal gills present or absent.  Common and widespread."

Let's have a look.  On this close up of the head, we can see 1) the "yellow spots lateral to the median ocellar spot," 2) how the median ocellar spot is nearly congruous with the yellow band near the labrum, 3) and the row of spinules on the occiput, typical of the genus.

For the abdomen --

easy to see the paired pale markings on terga 3-5.  We can almost see that the anal gills are absent (were it not for the silt on the nymph!), and we can see the transverse band (bands?) on the femora.

Paragnetina fumosa.  Sweet!

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The small winter stoneflies were numerous -- 3-4 in every leaf pack that I picked up.  Still immature, but the wing pads are fully developed.  Most likely, Allocapnia pygmaea which is the most common species we see.

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Our streams are finally dropping, but as you can see, the leaf packs are still pretty muddy from the high, fast conditions we've had of late.  Still, we should be able to start looking again.
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Note:  On reflection, I think I misidentified the "transverse bands" on the femora.  On this nymph, I see one "full" and one "partial" transverse band on the femora.

Goera time at Entry Run in Greene County

Too much rain has been a real problem so far this autumn.  Two weeks ago -- or was it three? -- we were hit with hurricane rainfall, over 8 inches.  Then this week we had another 4 inches on Wednesday.  The small mountain streams have cleared and started to drop, but the water was still fast and high today in Entry Run.

Still, I was quite sure I'd see some Goerids -- "weighted case-makers" -- and I did.  And I got some good photos of this one, a Goera fuscula, a species on which Beaty comments: "Mountains only.  Rare with less than 15 BAU (Biological Assessment Unit) records."  ("The Trichoptera of North Carolina," p. 87.)  While I often see G. calcarata in other small streams, this remains the only place that I've found fuscula.

G. fuscula has two distinguishing features. 1) "4 pairs of sclerites on metanotum," and 2) "sternal thoracic plates distinct."  (Beaty, p. 87)  In this case, one set of the sclerites -- those on the right side -- show up clearly in one of my photos.

The "sternal thoracic plates" require a microscope photo.

I saw a fair number of Goerids today, but they're very hard to pick up.  The cases sit on the tops and the sides of the rocks, but they're not really attached.  It's either a clean pick with the tweezers or they slip to the bottom.
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Saw a number of flatheaded mayflies.  The one that I kept for photos was Maccaffertium merririvulanum.

There are two Macs that we typically see in these small mountain streams in the winter: M. merririvulanum and M. pudicum.  M. pudicum has a distinct ventral pattern; on merririvulanum nymphs it's the dorsal pattern that gives them away.  They have distinct "V- shaped" light areas on terga 5, 7 and 8.  The marking on 8 isn't real clear in this photo, but I assure you it's there.

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Two other insects worth noting today.  One is a tiny, tiny Lepidostomatid.  The case was so tiny that at first, I wasn't sure what it was.  Still, the photos turned out alright.  (The case measured 3.5 mm; the larva was only 2!)

Like that first photo since you can see the eye on the larva, and you can see that the larva has started to convert its case from one made of sand grains into one made out of sections of leaves.

The other find was a shocker.  I found two, tiny Ephemerella subvaria spiny crawler mayflies!  I was stunned.  This is the first time I've found this species outside of the Rapidan River.   The bad news is that I didn't get any good photos.  Nonetheless...

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It was good to get out today.  Sunny and cool, and I love the drive up South River valley.