There is little information available on Naviculaidcta that is pertinent. See here for listing of references.
Naviculadicta, species undetermined, identification uncertain - poss Mayamaea. Found in core TL1 at Three Lakes, at 5.99 m depth.
See Naviculadicta on Algaebase or
Diatombase. Not found on Diatoms.org or on the Natural History Museum of Wales website.