Systematics of Triatoma sordida, T. guasayana and T. patagonica (Hemiptera, Reduviidae)

Abstract

Because of the relative epidemiological significance of Triatoma sordida, T. guasayana and T. patagonica, and the need to resolve doubts about their taxonomic validity, we report here a detailed taxonomic comparison of the three species using multivariate analysis of morphometric measures combined with comparisons of their genitalia and antennal structures. From the 17 metric variables studied, the length of the second segment of the rostrum and the anteocular length provided a discrimination function able to separate without error T. sordida from T. guasayana and T. patagonica. The multivariate discriminant functions classified T. guasayana and T. patagonica with an error of 2.44%. Comparison of the male genitalia of T. guasayana and T. sordida showed that there are minor differences in the articulatory apparatus, the median process of the pygophore, the phallosome support and the vesica, with bigger differences in the endosomal process and the phallosome. However, the already described male genitalia of T. patagonica is very similar to that of T. sordida. Analysis of antennal structure by scanning electron microscope showed that sensilla distribution around the pedicel is slightly different in the three species and sensilla density is highest in T. sordida and lowest in T. patagonica. The study showed that the three species form a closely related group. The results confirm the earlier classification of sordida and guasayana as separate species, but they raise some doubts about the taxonomic status of T. patagonica.

Inter-specific and developmental differences on the array of antennal chemoreceptors in four species of triatominae (Hemiptera: Reduviidae)

“…The shortest Mahalanobis distances obtained for Rhodnius species compared with Triatoma species, support Schofield's (1988) idea of a monophyletic origin of the Rhodniini and their similitude in habitat and hosts. On the other hand, both species of Triatoma, very well known for their differences in habitats and behaviour (Lent & Wygodzinsky 1979, Gorla et al 1993, Schofield 1994 showed important differences in the sensilla pattern. Zacharuk (1985) points out that in insect antennae, the scape and pedicel bear primarily mechanosensilla and that the greatest number of antennal sensilla, particularly chemosensilla and thermo-hygroreceptors, occurs on the flagellum.…”

Molecular research and the control of Chagas disease vectors

“…sordida, T. garciabesi, T. guasayana and T. patagonica are very similar but display distinct synanthropic trends; their overlapping ranges and high intraspecific anatomical variability make specific determination complicated (Gorla et al 1993). Allozyme electrophoresis confirmed sordida, guasayana and patagonica as valid taxa, and led to the revalidation of T. garciabesi and the discovery of two cryptic species within T. sordida (García et al 1995, Panzera et al 1997, Jurberg et al 1998, Noireau et al 1998.…”

Characterization of Triatoma guasayana biotopes in a hardwood forest of Santiago del Estero, Argentina

“…All the triatomines were shipped alive to the laboratory for species determination (Abalos & Wygodzinsky 1951, Gorla et al 1993) and instar and sex identification. The remaining arthropods, fixed in ethanol 70% in the field, were determined using appropriate keys.…”