Black identations on pseudobulbs?

[Fredmax]

Hi, sorry for the stream of questions but hopefully I can assist others when I get the hang of this.

I'm encountering these black marks across some of my plants bulbs and would love to understand the cause? Do the pictures look like mite or insect damage, or a result of fungus?

I'd like to apply a treatment promptly but don't want to use a blanket approach without knowing what's occurring, I'm hoping someone here has seen this before.

Thanks