A morphometric analysis of blood trypomastigotes identified as Trypanosoma
minasense, T. saimirii, and T. rangeli harbored by squirrel monkeys from
the Brazilian Amazon was performed. Additionally, morphological and
biological comparative analyses were conducted of T. saimirii-like and T.
rangeli development forms from haemoculture and xenodiagnosis.
Illustrations are given of blood trypomastigotes as well as of developing
flagellates in triatomine and axenic culture. Mean values of blood
trypomastigotes of T. saimirii differ statistically from those of T.
rangeli in only two out of ten morphological characters measured, and
ranges overlapped. The developing forms of T. saimrii-like parasites were
essentially identical in both xenodiagnosis and haemoculture to those of T.
rangeli. Trypanosomes confirmed as T. rangeli were transmitted to mice by
the bites of the great majority of triatomines that fed on T. saimirii-like
infected monkeys. We conclude that, based on morphology and on the
development in triatomine bugs and haemoculture, T. saimirii should not be
considered a distinct species. We therefore propose T. saimirii to be a
junior synonym of T. rangeli.
