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water beetle - Laccophilus maculosus

water beetle - Laccophilus maculosus
Harvard, Worcester County, Massachusetts, USA
June 17, 2006
Found in a puddle in the middle of a path. This was the best picture I could get. It wouldn't stop moving.

Chitonomyces on Laccophilus
I am pretty sure this is not Chitonomyces, although I would have to see the beetle in person to be sure. There are other common ectoparasites of Laccophilus, I believe I have found what you photographed above, or something similar, and it is not Chitonomyces. Does it have a blackened foot?

You're correct
Hi Lauren!
Didn't know you were active on this forum - cool!
I think I have found the same as well. It is even smaller than a Laboulbeniales thallus and doesn't have the typical rigid structure (and as you mentioned it has no foot, as I remember correctly). So I fully agree with you.



Laccophilus maculosus
id confirmed

This is definitely a dytiscid diving beetle, and it reminds me of the genus Laccophilus. I'd really rather have a second opinion, though, as aquatic insects are not my strong suit.

I'll place it in the family page for now. Thanks Eric.

Any idea what's going on at t
Any idea what's going on at the rear portion of the elytra? Was that a relection on the water or was it actually on the beetle?

air bubbles?
I've seen these beetles with an air bubble at the tip of the abdomen most of the times I've caught them. The other white stuff on the elytra might be air caught on hairs, or it could be something on the water surface.

Could it be a fungus?
Reminds me of what we sometimes see on Ladybird Beetles.

Could be a fungus
It was in a stagnant puddle of water. I never even noticed the white stuff when I had the beetle, it was moving so much.

Laboulbeniales fungus
Hi Tim --

This is definitely Laboulbeniales fungi on the elytra of the host. Probably of the genus Chitonomyces.

Chitonomyces is a fascinating genus. There are around 16 different species that grow on Laccophilus, all in very specific places on the host. It's not clear yet whether they are different species but at present it appears that they are and that they grow in very specific positions: a phenomenon called position specificity.

Monica Hughes

This may be Chitonomyces indeed. There's a recent paper on the position-specificity issue in the genus Chitonomyces. There are 13 species of Chtinomyces detected on one single host of Laccophilus maculosus, with the help of molecular tools Goldmann & Weir (2012) found out that there are actually only six species of Chitonomyces, all with two (or three) position-specific morphotypes. See:

Very challenging story!

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