I think it’s going to vary a lot by taxon and gall type.
re: Your example
Ordinarily, I’d say that since the suggestion’s thumbnail in the dropdown list is only one pic (unless they view it or use the Identron), to use the gall…after all, if you only have 1 pic, make it the one that matches what people will likely see.
I see your point about it looking like a plant, though, so maybe swapping the first and second photos would help…the one that’s currently second shows there’s something at the center of the plant tissue (helpful for the suggestion’s single thumbnail), while the other shows the gall itself.
