 The genome is small, low in G+C content, and lacks most amino-acid biosynthesis enzymes.The earliest report of this genus appears to have been that of Carlos Chagas in 1909, who discovered it in experimental animals, but confused it with part of the lifecycle of "Trypanosoma cruzi" (causal agent of Chagas disease) and later called both organisms "Schizotrypanum cruzi", a form of trypanosome infecting humans.The rediscovery of "Pneumocystis" cysts was reported by Antonio Carini in 1910, also in Brazil.