SYSTEMATICS OF TRIATOMA-SORDIDA, T-GUASAYANA AND T-PATAGONICA (HEMIPERA, REDUVIIDAE)

Because of the relative epidemiological significance of Triatoma sordi da, T. guasayana and T. patagonica, and the need to resolve doubts abo ut their taxonomic validity, we report here a detailed taxonomic compa rison of the three species using multivariate analysis of morphometric measures combined with comparisons of their genitalia and antennal st ructures. From the 17 metric variables studied, the length of the seco nd segment of the rostrum and the anteocular length provided a discrim ination function able to separate without error T. sordida from T. gua sayana and T. patagonica. The multivariate discriminant functions clas sified T. guasayana and T. patagonica with an error of 2.44%. Comparis on of the male genitalia of T. guasayana and T. sordida showed that th ere are minor differences in the articulatory apparatus, the median pr ocess of the pygophore, the phallosome support and the vesica, with bi gger 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 ele ctron microscope showed that sensilla distribution around the pedicel is slightly different in the three species and sensilla density is hig hest in T. sordida and lowest in T. patagonica. The study showed that the three species form a closely related group. The results confirm th e earlier classification of sordida and guasayana as separate species, but they raise some doubts about the taxonomic status of T. patagonic a.