Based on the leaves I'm seeing in the background...I would also say it's not acaulis. B acaulis has long, pendant leaves that are fatter than many of the other pendant brassavolas. It's also touchier to grow ...I know this from experience.
Are you sure it's a species...or could it be a hybrid?
There has been some confusion w/in the genus and w/out the original grower/vendor giving you an ID...it will likely be very hard to put anything more than Brassavola to your plant.