External female genitalia of Triatoma jatai, Triatoma costalimai and Triatoma williami (Hemiptera: Reduviidae: Triatominae)

Abstract

Background Taxonomic identification of triatomines is generally performed based on aspects of their external morphology. However, the use of a multidisciplinary approach, considering morphological aspects of the external genitalia, morphometry, genetics, and phylogeography has been suggested, especially for similar and/or cryptic species. The rupestral species Triatoma jatai Gonçalves et al., 2013, Triatoma costalimai Verano & Galvão, 1959 and Triatoma williami Galvão et al., 1965, which are morphologically similar, have been found naturally infected with Trypanosoma cruzi (Chagas, 1909) in wild, peridomestic, and intradomestic environments, representing a risk of new outbreaks of Chagas disease. This study presents morphological description complementation of these species, with an emphasis on the structures of the female external genitalia, using scanning electron microscopy. Methods The females of T. jatai and T. costalimai (n = 10 of each) were captured in the Brazilian municipalities of Paranã and Aurora do Tocantins and were identified with the use of a dichotomous key for the Matogrossensis subcomplex. Females of T. williami (n = 5), were obtained from a laboratory colony. The females were cut transversely at the sixth abdominal segment and examined under scanning electron microscopy (SEM) at the Oswaldo Cruz/Fiocruz Institute Electronic Microscopy Platform. Results It was possible to differentiate the three species based on the characteristics of urotergites VII, VIII and IX and urosternite VII, as well as the genital plaques, gonocoxites, and gonapophyses. To our knowledge, morphological differences in the spines present on gonapophysis 8 in triatomines are described here for the first time. Conclusions The results show that external genitalia of females are useful structures to differentiate T. costalimai, T. jatai and T. williami. SEM analysis contributes to and corroborates, together with other tools morphological and molecular, the distinction of the three species.

Triatoma guazu Lent and Wygodzinsky Is a Junior Synonym of Triatoma williami Galvão, Souza and Lima

“…In contrast, the low genetic divergence, lack of morphological diagnostic characters, and low morphometric distinction observed between T. guazu and T. williami corroborate previous studies which stated that they are very similar taxa [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. Additionally, the variation in the spots pattern in the connexivum is compatible with phenotypic variations between populations of the same species, possibly a consequence of different ecological characteristics, not standing as a feature to consider them as a separate species [ 14 , 39 ].…”

“…Noireau et al [ 15 ] observed a great similarity between sympatric specimens of T. williami and T. guazu , collected in the male type locality of the latter species, when analyzing 18 isoenzyme loci and four measurements of each, the head and thorax structures through traditional morphometry. In regard to the genitalia of the species studied here, Lent et al [ 14 ] described the male genitalia of T. guazu and Teves et al [ 16 ] described the female genitalia of T. williami . The former authors illustrated their description with drawings, while the latter with Scanning Electron Microscopy images.…”

Triatoma williami in intradomiciliary environments of urban areas in Mato Grosso State, Brazil: domiciliation process of a wild species?

“…The identification of T. williami was conducted based on external morphological characteristics. In such analyses, the importance of these structures in the identification of specimens was confirmed, as previously discussed by Teves et al [ 37 ].…”

Triatoma Williami Galvão, Souza e Lima, 1965 (Hemiptera, Triatominae) in Intradomiciliary Environments of Urban Area in Mato Grosso State, Brazil Domiciliation Process of a Wild Species?

“…2A-E). Such analyses con rmed the importance of these structures, as previously discussed by Teves et al (2020). Based on this information, the activities of the ChD surveillance team are triggered.…”