Just though of a way to check whether trifasciata or guineensis. Root a leaf cutting to see what develops from it. Should be able to tell it from there. Most cuttings loose the variegation and reverts back to original species.
Does anyone have anything to add to this?

In my imagination, I have thought that "guineensis" was brought to the New World from Africa maybe in the later 1700s or 1800s as a source of hemp and became naturalized. At one time I thought it might be a form of metallica, but a recent report by a S Fl Botanist said the wild sans growing in south FL was hyacinthoides, so I changed my mind. Such a plant being grown as a crop for a few hundred years could easily lose some of it's original traits. Like Stush says, we will probably have to await further genomic studies.

I wondered what became of S. guieneesis. On these forums persons are occasionally impressed by size. I wanted to share that in 1978 or so I saw what I believe to have been a S. guieneesis, at that time, that was noticeably taller than I was. It may have been seven foot tall.

BTW, ETA. and all that. The best site I have found is: Search results — The Plant List - 160 plant name records match your search criteria Sansevieria.

• "Sansevieria guineensis (L.) Willd.
  is a synonym
  of Sansevieria hyacinthoides (L.) Druce

• This name is a synonym of Sansevieria hyacinthoides (L.) Druce."

Old thread. A seven foot tall leaf. That would be amazing. Never heard of any S. hyacinthoids getting to that size. Guineensis is an old name not much used any more. Metallica is in it's own class.

Thanks for the great reference database you supplied.