Sure.
Aside from you, only three other members have uploaded pictures of Dietes iridioides to the database. It doesn't seem particularly onerous to request that you contact them first about moving the pictures. I have done this many times when I KNEW an image was incorrectly ID'ed. As long as it's done politely, there shouldn't be any problems.
I shouldn't speak for the other admins, but perhaps I can in this case. We are extremely reluctant to move a member's picture just because another member says it should be. If the owner of the picture agrees, they can easily request a move. If they don't agree, then the picture needs to be clearly and obviously wrong before I'd even think about moving it. The only time I've moved a picture without talking to the owner first was when we've had misspelled entries in the database and I had to move pictures to the correctly spelled entry so the misspelled one could be deleted.
