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

Abstract

Triatoma guazu Lent and Wygodzinsky and Triatoma williami Galvão, Souza, and Lima (Hemiptera: Triatominae) are found in human dwellings and are potential vectors of the protozoan Trypanosoma cruzi, the etiological agent of Chagas disease. Triatoma guazu was described based solely on a single female specimen, from the municipality of Villarica, Guairá Department, Paraguay, and posteriorly, a male from Barra do Garças, Mato Grosso, Brazil was described and designated as the allotype of this species. Triatoma williami is found in the central-west of Brazil between Goiás, Mato Grosso, and Mato Grosso do Sul. However, the taxonomic "status" of these species is questioned. Previous studies indicate the lack of isoenzymatic diagnostic loci, morphometric similarity, low genetic divergence, and close evolutionary relationship of these species. In this study, we compared the morphology, morphometry, and mitochondrial DNA fragments of the populations of the two species. The morphological diagnostic characteristic among these species is the difference in the connexivum spots pattern, which has been recognized as a phenotypic variation that exists among populations resulting from ecological diversity. Furthermore, our analysis also revealed the morphometric similarity and low genetic divergence between these species. Therefore, in the present paper, we formally propose T. guazu as a junior synonym of T. williami.

Keywords: Triatominae; geometric morphometry; mitochondrial DNA; morphological analysis; synonym.

Figure 1

Species studied, dorsal view: (A) Triatoma guazu; (B) Triatoma williami; (C) Triatoma matogrossensis; (D) Triatoma oliveirai. Scale 5.0 mm.

Figure 2

Triatoma williami (paratype, female, deposited in CEIB): (A) Dorsal view; (B) Ventral view; (C) Connexivum, dorsal view; (D) Connexivum, ventral view; (E) Labels. (A–D) Scale 5.0 mm.

Figure 3

Triatoma williami (allotype, male, deposited in CEIB): (A) Dorsal view; (B) Ventral view; (C) Connexivum, dorsal view; (D) Connexivum, ventral view; (E) Labels. (A–D) Scale 5.0 mm.

Figure 4

Triatoma williami (paratype, male, deposited in CTIOC): (A) Dorsal view; (B) Ventral view; (C) Connexivum, dorsal view; (D) Connexivum, ventral view; (E) Labels. (A–D) Scale 5.0 mm.

Figure 5

Triatoma guazu (allotype, male, deposited in CTIOC): (A) Dorsal view; (B) Ventral view; (C) Dorsal view of the connexivum; (D) Ventral view of abdomen, including; (E) Labels. (A–D) Scale 5.0 mm.

Figure 6

Triatoma williami, head, dorsal view of a showing landmarks (target spots) used in morphometric analysis. Scale 5.0 mm.

Figure 7

Variation of the connexivum spotting pattern. (A–C) Triatoma guazu, wide dark spots, in dorsal and ventral views; (D–F) Triatoma williami, narrow dark spots, in dorsal and ventral views. Scale 5.0 mm.

Figure 8

Factorial map built with the first two canonical vectors (CV) showing the head shape discrimination. (A) Between Triatoma guazu, Triatoma williami, Triatoma matogrossensis, and Triatoma oliveirai; (B) Without T. oliveirai.

Figure 9

Triatoma williami, male genitalia. (A) Phallus, lateral view, scale bar 0.5 mm. (B,C) Dorsal view, scale bar 0.3 mm. (B) Struts and apical portion of phallothecal plate (pointed by arrows). (C) Articulatory apparatus and pedicel. (D) Lateral process of endosoma, lateral view, scale bar 0.2 mm. (E) Median process of endosoma, superior view, scale bar 0.1 mm. (ba, basal plate arm; bb, basal plate bridge; dp, dorsal phallothecal plate; lp, lateral process of endosoma; mp, median process of endosoma; pd, pedicel).

Figure 10

Female external examined by scanning electron microscopy of Triatoma guazu. (A) Dorsal view (VII and VIII, tergites; IX and X segments). (B) Ventral view (VII, sternite; IX, segment; Gc8, gonocoxite VIII; Gp8, gonapophysis VIII). (C) Posterior view: (Gc8, gonocoxite VIII; Gc9, gonocoxite IX; Gp8, gonapophysis VIII; IX and X, segments).