The Rubiaceae is a very large Family in the Brazilian rainforest.
Myriam's plant does show similarities to Psychotria, but there are a large amount of other Genera that it is similar to as well.
Seeing the flowers and any other details will help, but very hard to find an ID a member of the one of the largest Families in the rainforest.
Cephalis & Palicourea are closely related to Psychotria. There are many other trees & shrubs with similar fruiting characters.
