Combined phylogenetic and morphometric information to delimit and unify the Triatoma brasiliensis species complex and the Brasiliensis subcomplex

Abstract

"Triatoma brasiliensis species complex" was defined as a monophyletic group of the species: T. brasiliensis, T. juazeirensis, T. melanica, and T. sherlocki. An alternative grouping scheme proposed the concept of "Brasiliensis subcomplex" which included the former species together with T. melanocephala, T. petrocchiae, T. lenti, T. tibiamaculata, and T. vitticeps. To evaluate the relationship among these taxa we combined the results obtained with four mitochondrial genes (12S, 16S, COI and Cytb, adding to 1811bp) and geometric morphometric analysis of wings and heads. Panstrongylus megistus was included in the analysis as it was previously found related to T. tibiamaculata, T. melanocephala and T. vitticeps. The results of both molecular and morphometric approaches clearly grouped the species analyzed into two monophyletic units, supported by both genetic and wing variability. The first one (G1) comprises the four species originally included in the T. brasiliensis species complex plus T. lenti and T. petrocchiae. The second group (G2) was composed by T. melanocephala, T. tibiamaculata and T. vitticeps, and remarkably, P. megistus if considering wing variability and phylogenetic results. Nevertheless, geometric morphometrics of heads provided a quantitative measurement that discriminates Panstrongylus from the Triatoma species based on the position of the antennal insertion relative to eyes, as it is used as the generic distinctive character. The discrepancy among approaches questions the validity of this character to define Panstrongylus genus. Independently of the chosen group definition -"T. brasiliensis species complex" or "Brasiliensis subcomplex"-we propose to delimit it to species of G1 that are all associated with the Caatinga biome in the Brazilian Northeast. G2 are the ones associated with the Atlantic Forest biome.

Keywords: Genotype; Phenotype; Triatominae.

Fig. 1.

Illustration adapted from Lent and Wygodzinsky (1979), showing landmarks on the heads. 1. Meeting point between neck and head at the left side; 2. Maximum curvature of the left eye; 3. Left point for the antenniferous tubercle insertion; 4. Closest left point between gena and anteclypeus; 5. Median anterior point of the anteclypeus; 6. Closest right point between gena and anteclypeus; 7. Right point for the antenniferous tubercle insertion; 8. Maximum curvature of the right eye; 9. Meeting point between neck and head at the right side.

Fig. 2.

Landmarks on the right wings. Corium portion: 1. Intersection of Pcu and Pcu + first anal vein; 2. Intersection of Cu and Cu–postocubitus (Cu–Pcu); 3. Intersection of Cu and M–Cu; 4. Intersection of media and cubitus (M–Cu); 5. Bifurcation of the radius (R) and median (M) veins; 6. Membrane portion on radius vein; 7. First intersection of R + M and Pcu (postocubitus); 8 Second intersection of R + M and Pcu (postocubitus); 9. Intersection of M and extension of Cu–Pcu veins; 10. Intersection of Pcu and Cu.

Fig. 3.

Maximum likelihood tree (-lnL = 10360.4245) of the combined analysis of 1811 bp of 16S, COI, CytB, and 12S sequences of South American triatomines. Molecular evolution models for each partition were GTR+I+G, except HKY+G for 12S. Thick clades represent those also recovered by at least one other phylogenetic method. Clade supports are: Maximum Likelihood bootstrap/Bayesian Posterior Probability/parsimony bootstrap. Monophyletic groups of species herein focused are represented by G1 (light blue) and G2 (dark blue).

Fig. 4.

Interspecific shape differences. Unrooted neighbor-joining trees from pairwise Mahalanobis (A, B) and procrustes (C, D) distance matrices for wings (A, C) and heads (B, D) geometric morphometric datasets. Monophyletic groups of species herein focused are represented by G1 (light blue) and G2 (dark blue).

Fig. 5.

Shape changes for the first component analysis of heads (A) and wings (B). Light blue consensus is related to Group 1 (Triatoma brasiliensis, T. juazeirensis, T. lenti, T. petrocchiae, and T. sherlocki) whereas the dark blue for Group 2 (T. tibiamaculata, T. vitticeps, and Panstrongylus megistus).