Abstract Triatoma melanocephala is an endemic species of Brazil. Phenotypic (external morphology) and molecular studies were performed to contribute to the taxonomy and phylogeny of triatomines, since few studies on the internal morphology of these were found. In order to contribute to the biological, morphological and taxonomic knowledge of the subfamily Triatominae, this work describes the internal morphology of the reproductive apparatus of adult males and females of T. melanocephala. For this work 30 specimens from Jequié, Bahia, Brazil were used. Triatoma melanocephala's reproductive system included slim spermathecae insertions, large/medium rounded terminal bodies, and irregular ellipsoid-shaped testicles with a transparent, vitreous appearance. These results contribute to the knowledge of the reproductive biology of this species of vectorial importance and show taxonomic relevance, as well as possible application in systematic studies.

Resumen Triatoma melanocephala es una especie endémica de Brasil. Se realizaron estudios fenotípicos (morfología externa) y moleculares para contribuir a la taxonomía y filogenia de los triatominos, ya que se encontraron pocos estudios sobre la morfología interna de estos. Con el fin de contribuir al conocimiento biológico, morfológico y taxonómico de la subfamilia Triatominae, este trabajo muestra la morfología interna del aparato reproductor de adultos machos y hembras de T. melanocephala. Para este trabajo se utilizaron 30 especímenes recolectados en Jequié, Bahía, Brasil. El sistema reproductivo de T. melanocephala incluye inserciones delgadas de espermatecas, cuerpos grandes/medianos con terminaciones redondeadas, y testículos de forma elipsoidal irregular con una apariencia transparente y vitrea. Estos resultados contribuyen al conocimiento de la biología reproductiva de esta especie de importancia vectorial y muestran relevancia taxonómica, así como su posible aplicación en estudios sistemáticos.

ABSTRACT Background: Trypanosoma cruzi presents great variability in morphology, virulence, pathogenicity, avoidance of the host immune system, and antigenic constitution, associated with different clinical manifestations of the disease. Methods: Two strains of T. cruzi were cultivated in liver infusion tryptose to determine growth kinetics, morphometry and molecular characterization using restriction fragment length polymorphism polymerase chain reaction. Results: The biological parameters showed sharp growth by the 7th day. Morphologically, both strains showed short and thin forms and were classified as Group I. Conclusion: Group TcI presents cardiac manifestations and T. sherlocki is adapting to the home environment, requiring attention to future problems.

Abstract: INTRODUCTION: To characterize Trypanosoma cruzi (TcI) isolated from a Panstrongylus megistus specimen found in one of the biggest metropolitan areas of Latin America, the relationship between the TcI group of T. cruzi and the transmission cycle in the urban environment was studied. METHODS: The T. cruzi strain, Pm, was isolated in a culture medium from the evolutionary forms present in the hindgut of a live male specimen of P. megistus found in the Jabaquara subway in São Paulo City. The sample from the triatomine showed trypomastigote forms of Trypanosomatidae, which were inoculated in the peritoneum of Balb/c mice. The sample was then inoculated in Liver Infusion Tryptose medium and J774 cells for the molecular identification and characterization of the parasite. The Pm strain of T. cruzi was identified by isolation in axenic culture medium, and based on the morphology, cell infection, growth kinetics, and molecular characterization. RESULTS: After isolation, the protozoan was identified as T. cruzi. No parasites were detected in the peripheral blood of the animal, which can be a characteristic inherent to the strain of T. cruzi that was isolated. Cell invasion assays were performed in triplicate in the J774 cell line to confirm the invasive ability of the Pm strain and revealed amastigote forms of the parasite within macrophages. CONCLUSIONS: Our biological and molecular characterizations helped understand parasite-host interactions and their evolutionary history in context of the associations between vectors, ecotopes, hosts, and groups of the parasite.