Robert did not comment on the question of D. ?. although I do believe he is aware of this plant. I will write to him with an introduction to you, and will inquire if he wishes the correspondence. He is a very kind (but busy) gentleman and if he is willing I will send you his email addy.
You are correct, the seeds are fusiform and do not support the determination for Drosera dielsiana based on this criteria.
I have an off topic question for you. Have you ever seen any Drosera natalensis from Madagascar?
Dr. Schlauer told me once in a correspondence that this locale is likely to have the most "pure" D. natalensis, but I have never seen these plants and would very much like to!