Internal anatomy: what is this structure ?

[vounti]

I received a binocular magnifier today so Im checking some exuvia and I saw a structure that I don't know on the inside of the carapace. It seems like the number of structure depends on the species

It might be something related to the muscles that control the legs ? Anyone has an idea ?

The picture is from a 2inches Megaphobema robustum exuvia.

 

[xXTristinaXx]

It looks like those dots that you see on top of the carapace. Neveming, it is on the bottom of the T
Forget what I said

kinda looks like it has something to do with legs

 

[AphonopelmaTX]

I received a binocular magnifier today so Im checking some exuvia and I saw a structure that I don't know on the inside of the carapace. It seems like the number of structure depends on the species

It might be something related to the muscles that control the legs ? Anyone has an idea ?

The picture is from a 2inches Megaphobema robustum exuvia.

They are called sternal sigillae (singular sigillum) and they are the muscular attachment points between the sternum and carapace. When those muscles are contracted, the carapace and sternum are compressed which increases hemlymph pressure in the prosoma. Essentially, increasing pressure of hemolymph to the legs.