Exactly! This is what bothers me. Small yellowish spots correspond to the original description of Sybra humeralis, but the shape of the humeral spot is different and large light area behind the humerus is completely missing.
It is at least near to S. humeralis, maybe you can clean the surface of your spm for a better view of the tomentation this is really sticky, and maybe we can see a whitish area
OK, I'll try to clean it, although it does not seem noticeably dirty, as it is possible to see small yellowish spots on sides. In any case I'll return to this topic, maybe with more photos.