species T. vivax. Nannomonas contains T. congolense. Stercorians are trypanosomes passed to the recipient in the feces of insects from the subfamily Triatominae (most importantly Triatoma infestans). This group includes Trypanosoma cruzi, T. lewisi, T. melophagium, T. nabiasi, T. rangeli, T. theileri, T. theodori. The subgenus Herpetosoma contains the species T. lewisi. The subgenus Schizotrypanum contains T. cruzi and a number of bat trypanosomes. The bat species include Trypanosoma cruzi marinkellei, Trypanosoma dionisii, Trypanosoma erneyi, Trypanosoma livingstonei and Trypanosoma wauwau. Other related species include Trypanosoma conorhini and Trypanosoma rangeli. Evolution The ancestor of modern trypanosomes absorbed a green alga around one billion years ago and co-opted some of its genetic material. This has resulted in modern trypanosomes such as T. brucei containing essential genes for the breakdown of sugars that are most closely related to plants. This difference may be used as the target of therapies. The relationships between the species have not been worked out to date. It has been suggested that T. evansi arose from a clone of T. equiperdum which lost its maxicircles. It has also been proposed that T. evansi should be classified as a subspecies of T. brucei. It has been shown that T. equiperdum has emerged at least once in Eastern Africa and T. evansi at two independent occasions in Western Africa. Selected species Species of Trypanosoma include the following: T. ambystomae. in amphibians T. antiquus, extinct (Fossil in Miocene amber) T. avium, which infects birds and blackflies T. bennetti, which infects birds and biting midges T. boissoni, in elasmobranch T. brucei, which causes sleeping sickness in humans and nagana in cattle T. cruzi, which causes Chagas disease in humans Trypanosoma culicavium, which infects birds and mosquitoes T. congolense, which causes nagana in ruminant livestock, horses and a wide range of wildlife T. equinum, in South American horses, transmitted via Tabanidae, T. equiperdum, which causes dourine or covering sickness in horses and other Equidae, it can be spread through coitus. T. evansi, which causes one form of the disease surra in certain animals including camels (a single case report of human infection in 2005 in India was successfully treated with suramin) T. everetti, in birds T. hosei, in amphibians T. irwini, in koalas T. lewisi, in rats T. melophagium, in sheep, transmitted via Melophagus ovinus T. parroti, in amphibians T. percae, in the species Perca fluviatilis T. phedinae T. rangeli, believed to be nonpathogenic