Not to be considered as synonym of Peperomia magnoliifolia (Jacq.) A.Dietr. as was published by Boufford, 1982.
Many botanists have tried to fit P. spathulifolia and its synonyms in P. magnoliifolia or P. obtusifolia and a large number of P. spathulifolia specimens can still be found among collections of those two taxa. P. magnoliifolia and P. obtusifolia can be distinguished most easily by their fruit morphology. Fruits of P. magnoliifolia are ellipsoid and show a short beak. Fruits of P. obtusifolia have an urn-like shape and show a long slender beak with a distinct curl at the end. The fruits of P. spathulifolia are somewhat between these extremes and this explains why specimens are often identified as one of these two species. The fruit body of P. spathulifolia is ellipsoid like in P. magnoliifolia but its beak is longer and curved. However, it lacks the curl at the end as in P. obtusifolia [Mathieu & Callejas, 2006: 353].
P. spathophylla appears to be very close to (if not identical with) P. septentrionalis Brown [Mathieu 2008, pers. comm.]