This page list Crinum x submersum Herbert as a natural hybrid of C. scarbrum and C. americanum. For it to be a natural hybrid in Brazil, I would think both species would have to exist in Brazil.
The text says C. americium but I believe this is a typo.
Crinum x submersum Herbert is a natural hybrid found in Brazil. It is an obvious cross of C. scarbrum and C. americium, and is quite sterile. Numerous duplicate crosses, man-made or hummingbird pollinated, have appeared since Herbert's time. The variants amongst both C. americanum and C. scabrum result in significant diversity as shown in Figures 25 and 26 below. Usually the petals are intermediate in form, indicating some intermixing of genes.
http://www.crinum.org/crinpics...
