Friday, December 23, 2016

Perlodid stonefly Malirekus hastatus in a VERY small stream in Sugar Hollow

On Wednesday I went to a very small stream in Sugar Hollow, probably the smallest stream that I visit.

The water, as you can see, was low, and I despaired of finding anything at all.  I was hoping to find some Uenoids, hoping to find N. ornatus, but I didn't see a single case.  I was also hoping to find that little casemaker that I found here at the start of last year -- Adicrophleps hitchcocki.

No luck.  What I did see in fairly good numbers was a Perlodid stonefly that is fairly common in Sugar Hollow in the winter -- Malirekus hastatus.  Beaty notes that these nymphs are "typically collected from small mountain streams and rivers."  He also notes that they're "predators -- engulfers."  ("The Plecoptera of North Carolina," p. 71)  I'd say that's an understatement.  They're vicious.  You cannot leave a mayfly with them in the same bowl.  Turn your head and that mayfly is gone -- engulfed!  If you want to collect them, do like I do and carry two bowls.

Here's Beaty's genus description.  "Lacinia with low marginal knob bearing a tuft of setae and ventral surface with a cluster of approximately 50 clothing hairs near base; labrum concolorous; head brown with distinct, completely enclosed pale M-pattern; pair of linear spots anterior to M-pattern; large suboval pale spots lateral to ocellar triangle; a faint ocellar spot present; occiput with large oval areas with brown reticulations, enclosed posterior by dark band and occipital setal row, a mostly single, irregular curved row of closely set spinules on back of head, obsolete near midline." (p. 71)

All of that looks like this.

On the species -- hastatus -- he adds: "Conical submental gills ... abdomen brown and often with a pair of pale submedial dots, some specimens with pale lateral dots and an obscure longitudinal, slightly darkened stripe between pale submedial dots."

You can see the abdomen markings in the photo above.  For the submental gills, they look like this.

I think I've commented before on the large heads on small nymphs like this one.  By February they change.

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