Hello Alan,
interesting, never heard of it. Looks to me like any variant of Limnophila aromatica, but this species is native of Asia, not South America (Belem => Brazil). Has the friend some further infos about the plant? Many newer plants with trader names as "Belem" and "Araguaia" are apparently imported via Japan, e.g. Rayon Vert. Also this plant?
What's the size of the leaves?
Greetings,
Heiko