Hello John,
I think you can be right with Franz von Werra. It's difficult to see, but I think the man here has the rank of Hptm.?
Mayer wore already as an Olt. his flying clasp with a pennant verticaly straight above the button of his breast pocket, while there is a photo of v. Werra, waering his clasp more to the left above the button and without a pennant. On the other hand, on most of the photo's, his nose looks wider than that of the man on this photo.
Regards,
Hugo.