Strange Spots Inside Exoskeleton

[Vanessa]

I've seen this before in my own collection, and they have also become more numerous with each moult, but I have not seen it to this extent. In my case, there is no evidence of these marks from the outside - only on the inside. However, in this case there are bald marks on the underside of her abdomen that correspond to the marks inside.
I always thought that it had something to do with the moulting fluid composition - perhaps too much protein, or other component - but I would like a more in-depth answer if anyone has one.
Also, I would like to know if anyone had a 'wet moult' occur in a spider who exhibited these 'burn' marks?
I tried searching using a few different parameters, but I cannot find something similar - even under the cyst information thread.
I have permission to repost this photo from a member of a group that I moderate on Facebook as per the second photo below.

 

[Ghost56]

Almost looks as if some sort of parasite or something was feeding on the abdomen from the inside. That's really odd looking. Maybe @boina would have an idea of what it could be.

 

[Arachnid Addicted]

Hi @Vanessa
Have 3 questions:
1- these spots on your individuals suddenly disappeared? Did these cause any harm to your specimens?
2- the specimen you posted in this thread, kept going with these bald spots (externally) after it molted?
I've never seen this before, so I got interested to know more about it.
Thanks.

 

[Vanessa]

Hi @Vanessa
Have 3 questions:
1- these spots on your individuals suddenly disappeared? Did these cause any harm to your specimens?
2- the specimen you posted in this thread, kept going with these bald spots (externally) after it molted?
I've never seen this before, so I got interested to know more about it.
Thanks.

1 - My individual is fine. They are still getting the spots, but nothing to this extent. I can't remember which one of my gang that it is - I will look up the species when I get home.
2 - The one in the photos is doing great. Great appetite, very active, and doesn't seem to have any other concerns.

 

[Sarkhan42]

Coincidentally I just noticed one of my tiny slings exhibiting very similar light patches across the underside of the abdomen that I could not explain. I’ve not had a molt from it yet to compare to however.

 

[Feral]

Did these tarantulas get fed vertebrates? Especially within a month or so of molting?

I've read about mineral dystrophies that result from feeding high-calcium meals (vertebrates like mice, lizards, etc.) that produce "calcification of the soft tissues at the exoskeleton, as well as chitinization". It can be a cause anytime, as I understand it, but especially before a molt. That quote is from a 2014 study by Gaspar, et. al., on molting in captive A. geniculata.

 

[Vanessa]

I have received some feedback on the cause. Apparently there was a lecture at the BTS about this. I am still waiting on feedback about the danger level and what, if anything, we can do about it.

"BTS Lecture on this a couple of years ago. Vet giving lecture didn't know the cause, but the dark internal spots are melanin which is produced to isolate the pathogen/damage. Fungus Aspergillus flavus was given as a common internal pathogen (the yellow mould on dry crickets!)."

 

[darkness975]

I have received some feedback on the cause. Apparently there was a lecture at the BTS about this. I am still waiting on feedback about the danger level and what, if anything, we can do about it.

"BTS Lecture on this a couple of years ago. Vet giving lecture didn't know the cause, but the dark internal spots are melanin which is produced to isolate the pathogen/damage. Fungus Aspergillus flavus was given as a common internal pathogen (the yellow mould on dry crickets!)."

That sounds plausible. I was going to add that it almost resembles mycosis damage that affects desert dwelling scorpions such as H. arizonensis if kept too moist.

It too is caused by damage due to fungal infection.

 

[Feral]

Interesting, I was just reading today about the various strategies of the immune system of Ts and it mentioned the role of melanin in encapsulating perceived threats, but I didn't even put it together. It seems quite possible that the melanin deposits might be a reaction to the mineral dystrophies I mentioned.

 

[Vanessa]

That sounds plausible. I was going to add that it almost resembles mycosis damage that affects desert dwelling scorpions such as H. arizonensis if kept too moist.
It too is caused by damage due to fungal infection.

The person I got the information from says that the jury is still out on whether it poses any dangers. He suggested replacing the substrate and being extra diligent to remove cricket remains and boluses. What is your course of action when you find it on the scorpions?

 

[Feral]

I'm not familiar with treating aspergillosis in inverts, but in vertebrates like birds, dogs, and cats it usually only affects animals that have been immunocompromised in some way, like from inappropriate husbandry or much weight loss or underlying disease. And the disseminated aspergillosis form is even more rare in vertebrates, and almost always affects only immunocompromised animals. I wonder how this compares to its presence and growth in inverts and how they're affected (if it actually is aspergillosis that's the problem/organism in this case).

It would be extremely helpful to the hobby if someone with these spots took the T to the vet for work up with diagnostics like blood work, cytologies, culture & sensitivity, whatever's appropriate, then a course of whatever appropriate medication or treatment. And then of course getting their records and results and sharing them with the community. It could really help out other hobbyists and Ts in a big way!

 

[Brachyfan]

Sorry to hear about this Hope you can figure it out.

 

[Vanessa]

Thanks for the well wishes, but they are not my animal. The person that she belongs to says that she is acting fine, acting normally, and he will keep an eye on her. It sounds as if it is some sort of immune system response, so perhaps everything is under control.
I will keep everyone posted if I have any information.

 

[AphonopelmaTX]

I have received some feedback on the cause. Apparently there was a lecture at the BTS about this. I am still waiting on feedback about the danger level and what, if anything, we can do about it.

"BTS Lecture on this a couple of years ago. Vet giving lecture didn't know the cause, but the dark internal spots are melanin which is produced to isolate the pathogen/damage. Fungus Aspergillus flavus was given as a common internal pathogen (the yellow mould on dry crickets!)."

Was there any mention of a research paper on the topic or who the veterinarian was who gave the presentation? I would like to learn how he/ she arrived at that conclusion.

 

[Vanessa]

Was there any mention of a research paper on the topic or who the veterinarian was who gave the presentation? I would like to learn how he/ she arrived at that conclusion.

No, what I posted above is the extent of the feedback I got.

 

[darkness975]

The person I got the information from says that the jury is still out on whether it poses any dangers. He suggested replacing the substrate and being extra diligent to remove cricket remains and boluses. What is your course of action when you find it on the scorpions?

Unfortunately when mycosis is present on a scorpion there is nothing that can be done to reverse it. All that can be done is to keep the environment dry and prevent the fungus from surviving and therefore the damage spreading. If it is a younger specimen they can molt out of it but an adult is unfortunately stuck with it for the remainder of its life given that scorpions do not molt after their final molt to adulthood the way tarantulas do.