Triatoma vitticeps subcomplex (Hemiptera, Reduviidae, Triatominae): a new grouping of Chagas disease vectors from South America

Abstract

BackgroundTriatomines have been grouped into complexes and subcomplexes based largely on morphological and geographical distribution. Although these groupings are not formally recognised as taxonomic ranks, they are likely monophyletic. However, recent studies have demonstrated that some subcomplexes from South America did not form monophyletic groups, and reorganisations have been suggested. One suggested reorganisation is to exclude Triatoma vitticeps, T. melanocephala, and T. tibiamaculata from the T. brasiliensis subcomplex. However, T. vitticeps and T. melanocephala exhibit several similar characteristics, including morphologic, cytogenetic, and phylogenetic features, a factor which supports the creation of a new subcomplex. Thus, this study aimed to describe the T. vitticeps subcomplex.Results T. vitticeps and T. melanocephala are sister species and share a phylogenetic relationship, several similar morphological characteristics, the same composition of constitutive heterochromatin (Xs CG-rich and Y AT-rich), the same karyotype (2n = 20A + X1X2X3Y), and the same meiotic behaviour during spermatogenesis. Based on karyosystematics, for example, the T. vitticeps subcomplex may differ from all of the other subcomplexes from South America, as well as from the Rhodniini tribe and the genus Panstrongylus. We argue that the case of agmatoploidy involving the X chromosome was responsible for the karyotype divergence of this subcomplex in relation to the other South America subcomplexes.ConclusionsBased on the phenotypic characteristics (morphology) and genotypes (cytogenetics and molecular features), we propose the creation of the monophyletic T. vitticeps subcomplex, which we believe is distinct from all other subcomplexes from South America.

Triatoma brasiliensis species complex: characterization of the external female genitalia

“…Galvão et al (2003) listed 137 valid species distributed in 19 genera and six tribes within the subfamily Triatominae. However, taxonomic changes have occurred since then, such as descriptions of new species and redescriptions and/or revalidations of others (de Oliveira and Alevi 2017). Thus, there are currently 154 species, including151 extant and three fossil species ( T. dominicana , P. hispaniolae, and Paleotriatoma metaxytaxa ) distributed in 19 genera and grouped into five tribes, taking into account that the Linschosteini tribe has been currently included in Triatomini (Justi et al 2018, Lima‐Cordón et al 2019, Nascimento et al 2019, Poinar 2019).…”

“…Initially, “specific complex” was defined for triatomines as a set of species and/or subspecies with morphological similarities, hybridization ability, and molecular affinities (Carcavallo et al 2001). However, with the emergence of new taxonomic methodologies, several complexes were reorganized based on the need of groupings in natural assemblages (Alevi et al 2012a, 2017, Gardim et al 2014, Pita et al 2016). Currently, triatomines are clustered into six groups, eight complexes, and nine subcomplexes (Alevi et al 2017, Justi et al 2018).…”

Karyotype Evolution of Chagas Disease Vectors (Hemiptera, Triatominae)

“…Subsequently, Justi et al 5 observed that the Northern Andean uplift separated Triatoma maculata (restricted to the Amazon) from the other members of the group infestans (an evolutionary event that has not caused changes in the number of chromosomes). Furthermore, the authors report that Triatoma melanocephala (Neiva and Pinto, 1923) and Triatoma vitticeps (Stål, 1859) (subcomplex vitticeps), 17 although present in South America, are considered exceptions because they appear to have reached the Atlantic coast by dispersal and diversified before that event. Different from the species of the group infestans, which present 2n = 22 chromosomes, 9,11 T. melanocephala and T. vitticeps have 2n = 24 (20A + X 1 X 2 X 3 Y).…”

“…6,16 In the case of the subcomplex vitticeps, agmatoploidy resulted in a karyotype that makes it possible to distinguish these species from all the others in South America. 17 The group infestans includes the subcomplexes brasiliensis, infestans, maculata, matogrossensis, rubrovaria, and sordida. 15,18 Taking into account that many karyotypes of these subcomplexes have been described, all species analyzed have 2n = 22 (20A + XY), 9,11 and different subcomplexes emerged from different selective pressures (brasiliensis in the Caatinga Province, rubrovaria in the Pampean Province, infestans in the Chacoan Province, and sordida, matogrossensis, and some species of the subcomplex maculata in the Cerrado Province), 5,18 we suggest that all group infestans species have 2n = 22 chromosomes.…”

“…These results corroborate the phylogenetic relationship presented by Justi et al 5 because most species of the clades geniculatus and rubrofasciata have 23 (sex-determination system X 1 X 2 Y), 24 (sex-determination system X 1 X 2 X 3 Y), or exceptionally 25 chromosomes (sex-determination system X 1 X 2 Y). 8,[17][18][19] Gardim et al 20 pointed out the need for a general revision in the tribe Triatomini because Panstrongylus cannot be clustered separately from Triatoma. For example, the clade geniculatus consists of Panstrongylus spp., flavida complex, and Triatoma tibiamaculata, 5 and all studied species of this clade [except Panstrongylus megistus (Burmeister, 1835) and Panstrongylus lutzi (Neiva & Pinto, 1923)] 21,22 presented 2n = 23 (20A + X 1 X 2 Y), 9,21 which confirms the evolutionary relationship proposed.…”