yep, ph. mayoi seems just like what it is! but i can't believe it would be nutes; these guys are pro's - they sell and propagate lots of fantastic aroids and rather hard to find variegated philos and monsteras and lots more. though their labeling is rather poor, even for sales stuff. last year was an exceptionally warm winter - only a few nights around 56F, most days in hi 70s and low 80s. so temps would not be problematic. and by the way - what kind of nutes can produce such a well defined red margin? this plant and all of the rest is in covered greenhouses.
after i looked at asplenium ferns i see why you thought it was an asplenium. though it has long thin petioles, but the other aspleniums all seem to have fronds that start at the base. some of the frilly aspleniums look quite close. one more day and you'll know.
