Please excuse me, but I don't know, whether this could be from interest!
But unfortunately only in german!
www[dot]macwrench[dot]de[slash]wiki[slash]Dateien_und_Ordner_verstecken_und_sch%C3%BCtzen
Is it possible, that JD2 downloads a picture, but MAC OS creates a hidden folder, dependent of the dot at the begining of the file name?
And should be a hidden folder not be empty in MAC Finder?

Something seems different for me, between RGUS and ziege58!
Is it possble, that by RGUS always follows a underscore after the dot?
This seems not by ziege58 for me!

Could be the solution here?
www[dot]westwind[dot]com[slash]reference[slash]OS-X[slash]invisibles[dot]html



And something other:
en[dot]wikipedia[dot]org[slash]wiki[slash]Filename
bis2008[dot]frankbarth[dot]de[slash]pdf[slash]MACundPC[dot]pdf