RESUMO
Two new trypanosomatid species (Euglenozoa, Kinetoplastea) isolated from the intestinal tract of heteropteran insect hosts were described based on molecular phylogenetic analyses of Spliced Leader (SL) RNA gene repeats, glycosomal glyceraldehyde phosphate dehydrogenase, and small subunit ribosomal RNA genes, as well as by morphology. Leptomonas barvae n. sp., from a mirid host Collaria oleosa, was found to represent one of the closest monoxenous (one host) relatives of the dixenous (two hosts) parasitic genus Leishmania. This finding further supports the origin of these dixenous parasites from monoxenous progenitors in the Neotropics. Blastocrithidia largi n. sp., from a largid host Largus cinctus, is among a few members of this genus available in culture. The species is a close relative of Blastocrithidia triatomae and is a member of a new monophyletic phylogenetic group characterized by formation of straphanger cysts.
Assuntos
Heterópteros/parasitologia , Trypanosoma/classificação , Trypanosoma/isolamento & purificação , Animais , Análise por Conglomerados , Costa Rica , DNA de Protozoário/química , DNA de Protozoário/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Trato Gastrointestinal/parasitologia , Genes de RNAr , Gliceraldeído-3-Fosfato Desidrogenases/genética , Microscopia , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Dados de Sequência Molecular , Filogenia , Proteínas de Protozoários/genética , RNA de Protozoário/genética , RNA Ribossômico 18S/genética , RNA Líder para Processamento/genética , Análise de Sequência de DNA , Trypanosoma/citologia , Trypanosoma/genéticaRESUMO
Three new species of monoxenous parasites from the Neotropical Heteroptera are described on the basis of the ultrastructure of cells in culture, as well as gene sequences of Spliced Leader (SL) RNA, glyceraldehyde phosphate dehydrogenase (GAPDH) and small subunit (SSU) rRNA. The results have highlighted a striking discrepancy between the morphological (dis)similarities and the phylogenetic affinities among the insect trypanosomatids. Although each of the new species is characterized by a distinct set of morphological characters, based on the predominant promastigotes observed in culture, each of them has been provisionally assigned to the genus Leptomonas pending the future revision of this genus. Yet, instead of the phylogenetic affinity with the other members of this polyphyletic genus, the new species are most closely related to Crithidia species. Thus, the extremely long promastigotes of Leptomonas acus sp. n. and the unique morphological features found in Leptomonas bifurcata sp. n. sharply contrast with their respective relatives C. fasciculata and C. deanei both of which are typical choanomastigotes. The results clearly show that the current classification at the genus level is misleading and needs to be revised. The phylogenetic clades potentially representing the candidate new genera of monoxenous trypanosomatids have started to emerge from the presented analyses.