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Triatoma mexicana general view. (a) Hidalgo-Metztitlan, (b) Hidalgo-West, (c) Guanajuato, and (d) Queretaro.
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Triatoma mexicana is an endemic species of Mexico and is distributed in the states of Hidalgo, Queretaro, Guanajuato, and San Luis Potosi, being naturally infected with Trypanosoma cruzi, which increases its importance in the region. The species description was made in 1848, but there are only a few studies on its morphology, biology, and behavior....
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... Length 22.97 mm; width of abdomen 8.86 mm. General color black with orange marking on corium and connexivum (Fig. ...
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... and without exceeding the apex of the abdomen. Clavus black on basal half, brownish in the rest. Orange corium with a large dark brown spot in the middle and at the apex. The lateral edge of the corium is almost entirely orange (Fig. 2a). Abdomen-convex, ventrally flattened in segments III to V, not limited by edges, with small transversal striate. Short, thin, and sparse setae in the ventral portion. Abdomen brown. Orange connexivum, with black markings from the intersegmental suture and encompassing two-thirds of each segment diagonally towards the connexival suture, ...
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... with length 24.54 mm; width of abdomen 8.72 mm. General color black with yellow marking on corium and connexivum (Fig. ...
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... approaching or exceeding the apex of the abdomen. Clavus basally black, brownish in the rest. Yellow corium with a dark brown spot in the middle and at the apex. The lateral edge of the corium almost entirely yellow (Fig. ...
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... length 23.93 mm; width of abdomen 8.98 mm. General color black with brown-orange markings on corium and connexivum (Fig. ...
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... or exceeding the apex of the abdomen. Clavus basally black, brownish in the rest. Brown-orange corium with a black spot in the middle and at the apex. The lateral edge of the corium almost entirely brown-orange. The color of the corium in this population is the darkest of the four observed populations (Fig. ...
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... with length 23.79 mm; width of abdomen 8.44 mm. General color black, with orange markings on corium and connevixum (Fig. ...
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... approaching or exceeding the apex of the abdomen. Clavus basally black, brown in the rest. Orange corium with a large dark brown spot in the middle, which in some cases extends to the apex, in others; there is a separate spot at the apex. The lateral edge of the corium is almost entirely orange (Fig. ...
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... The current classification of Reduviidae species is still largely morphology-based and poorly and less comprehensively revised by modern approaches such as phylogenetics and species delimitation analyses using DNA sequence data. Thus, taxonomic obscurities and confusions in species recognition have been caused by cases of the cryptic species complex (Panzera et al., 2015;Zhao et al., 2021), male-female dimorphism in a single species (Kwadjo et al., 2010;Gil-Santana, 2017;Weirauch et al., 2017;Chen et al., 2021), and remarkable morphological polymorphism or variation among conspecific populations or seasonal generations (Stål, 1867;Distant, 1903;Moreno et al., 2006;Rivas et al., 2021;Vilaseca et al., 2021). Moreover, recent studies using molecular phylogenetic analyses have provided phylogenetic hypotheses or presumptions that claim the necessity of reexaminations of the boundaries of many genera and subfamilies in the current classification of the family (Weirauch & Munro, 2009;Hwang & Weirauch, 2012). ...
The genus Rhynocoris Hahn, 1834 is one of the largest genera of the subfamily Harpactorinae. This genus consists of 144 described species widely distributed in the Afrotropical, Palearctic, Sino-Japanese, Oriental, and Nearctic Realms. There are three species, Rhynocoris fuscipes (Fabricius, 1787), Rhynocoris marginellus (Fabricius, 1803), Rhynocoris mendicus (Stål, 1867) recorded in Vietnam. In this study, we attempted to re-examine the Rhynocoris species collected from Vietnam based on external morphology, genital morphology, and COI phylogeny to reveal the species delimitation of this genus in Vietnam. As a result, the independence of the three Rhynocoris species from Vietnam was confirmed. Moreover, R. mendicus was revealed as being a polymorphic species with two intraspecific morphological phenotypes.
... Classical studies on the triatomines have relied on morphological/chromatic (Rivas et al. 2021), cytogenetic (Borsatto et al. 2019), and mating (Correia et al. 2013) to classify vector species. These are often limited to a detailed evaluation of the dynamics of the host-vector relationship. ...
Triatomine bugs are mainly hematophagous insect transmitters of parasite Trypanosoma cruzi, the causal agent of Chagas diseases. This disease affects about six million to seven million people in the world, mainly in Central and South America. Currently, there is no vaccine, and the treatments are usually ineffective and with severe side effects. The main method to mitigate this disease has been through vector control. Therefore, it is essential to correctly identify of vector (triatomine) species. In this study, we implemented the Heteroduplex Assay of Cytochrome b (HDA Cyt-b) for the identification of five triatomine species: Triatoma infestans, Triatoma longipennis, Triatoma mazzottii, Triatoma picturata, and Triatoma protracta nahuatlae using DNA of Rhodnius prolixus as a probe. Main findings showed five specific heteroduplex patterns for each triatomine species, providing evidence that the HDA Cyt-b approach correctly identified these five triatomine species of public health importance. Our findings contribute for designing sound strategies for preventing vector transmission of Chagas disease.
... Antonio-Campos et al. 2021). However, there are other less studied species of triatomines such as Triatoma mexicana (Herrich-Schaeffer), which is an epidemiologically important vector of T. cruzi in central Mexico (Antonio-Campos et al. 2019;Rivas et al. 2021). This species is widely distributed in the States of Guanajuato, Hidalgo, Queretaro, and San Luis Potosi (Cruz-Reyes and Pickering-López 2006;Salazar-Schettino et al. 2010). ...
... T. mexicana has been reported in domiciliary, peridomiciliary, and sylvatic habitats. However, its microhabitat seems to depend on the geographic region in which it is found (Martínez-Ibarra et al. 2008;Antonio-Campos et al. 2019;Rivas et al. 2021). ...
... Since then, its geographic distribution has been reported in central Mexico including the States of Guanajuato, Queretaro, and San Luis Potosi ). Despite its importance as a vector of Chagas disease, there are few studies on its geographic distribution (Vidal-Acosta et al. 2000;López-Cárdenas et al. 2005;Villagran et al. 2008), entomological indices (Becerril-Flores et al. 2010Antonio-Campos et al. 2019), biological behavior (Salazar-Schettino et al. 2007;Martínez-Ibarra et al. 2008), and morphological description Rivas et al. 2021). There are only two studies on T. mexicana population genetics and phylogeny (Espinoza et al. 2013;Aguilera-Uribe et al. 2020), and genetic processes related to intraspecific variation, population structure, genetic drift, migration, gene flow, introgression, and pesticide resistance in this species remain largely unknown. ...
Triatoma mexicana is an important vector of Trypanosoma cruzi—the etiological agent of Chagas disease. This triatomine species occurs in central Mexico, but little is known about its genetic variability. Using Cyt-b gene as a genetic marker, in this study, we determined the population genetic structure of T. mexicana collected from the States of Hidalgo, Guanajuato, and Queretaro where populations are largely peridomiciliary. A Bayesian approach was performed for the design of phylogenies, median-joining networks, and clustering among populations of T. mexicana. Our results show that the Hidalgo population was the most distinct, with the highest genetic and haplotypic variation (Hd = 0.963, π = 0.06129, and ɵ = 0.05469). Moderate gene flow (Nm) was determined among populations of Hidalgo and Queretaro. Populations from the three states showed differentiation (FST) values ranging from 0.22 to 0.3, suggesting an important genetic differentiation. The phylogenetic analysis showed the presence of five well-defined groups, as well as the haplotype network, where 24 haplotypes were observed forming five haplogroups with high mutational steps among them: 68 (Hgo-W2), 26 (Qto), 59 (Hgo-M), 44 (Hgo-W1), and 46 (Gto). Genetic isolation was apparently inferred in the Guanajuato population; however, the Mantel test did not show correlation between genetic (FST) and geographic (km) distances (p = 0.05). The STRUCTURE analyses showed seven genetic clusters and it was observed that a single cluster predominates in each sampled location. However, genetic admixture was detected in four localities. Our results show evidence that there are multiple species within the collected sampling area.
... These parameters, such as defecation time after feeding (Martínez-Ibarra et al. 2015Nogueda-Torres et al. 2021), explain the practical importance of the subspecies, in addition to justifying different control strategies for each population. Already in cases of phenotypic plasticity, the changes are restricted to morphological changes (color, shape, or size), which does not justify the elevation of specific status, but these variations can indicate an initial process of divergence Nattero et al. 2013;Rivas et al. 2021). In Triatominae, there is no consensus on the parameters needed to differentiate phenotypic plasticity and a subspecies (Mas-Coma and Bargues 2009). ...
Due to its public health importance, as vectors of Chagas disease, the subfamily Triatominae, has received the attention of taxonomists. Knowing how to correctly identify these insects is of paramount importance for the surveillance and control of these vectors. Over many years, more than 40 triatomine subspecies were proposed. Infraspecific taxa are accepted as real entities in nature and recognized as biologically significant. Infraspecific diversity and population subdivision are frequently confused with the underlying mechanisms that lead to the formation of new species and species-level diversity. The distinction between infraspecific and interspecific divergence processes has received far less attention than species delimitation. In this work, new literature data on subspecies included in the subfamily Triatominae are presented. Data were compiled about Triatoma brasiliensis, Triatoma breyeri, Triatoma circummaculata, Triatoma dimidiata, Triatoma incrassata, Triatoma infestans, Triatoma phyllosoma, Triatoma protracta, Triatoma recurva, Triatoma rubida, Triatoma sanguisuga, Triatoma vitticeps, Panstrongylus megistus, Paratriatoma hirsuta, and Paratriatoma lecticularia subspecies. Although several of these subspecies have been synonymized, herein, we emphasize that some subspecies may be valid. Therefore, further studies are needed on the taxonomy, evolution, phylogeny, biogeography, ecology, physiology, and behavior of species to reinforce, or to invalidate the infraspecific status in the subfamily.
... This phenomenon is known as polychromatism (Monteiro, 1990;Vargas et al., 2016). Several species in different insect orders show such differences in their body coloration, but its most extreme extent can be clearly seen in some species of the order Hemiptera (Berniker and Weirauch, 2012;Souza-Firmino et al., 2015;Rivas et al., 2021). ...
... The similarities and differences of maculae patterns may depend on the geographical range of the studied samples. Also, examination of more specimens from different geographical regions will lead to more and more additions of unlimited chromatic variation patterns (Rivas et al., 2021). The range expansion of D. silphoides during the last few years as an invasive species outside its natural range in the Afrotropical region makes such work essential in order to prevent its misidentification throughout its new range (El-Hawagry et al., 2013;Novoselsky et al., 2015). ...
Polychromatism in adult Deroplax silphoides (heteroptera: scutelleridae) and a morphological examination of the immature stages, Saudi Journal of Biological Sciences (2022), doi: https://doi. Polychromatismin adult Deroplax silphoides (Heteroptera: Scutelleridae) and a morphological examination of the immature stages Abstract Polychromatism is a very common phenomenon in several insect orders. Adults of Deroplax silphoides show color variation in their bodies. In such cases, the identification of the immature stages is challenging and misleading. The field collection of adults and immature stages was conducted on the campus of Ain Shams University during the active period of the insect in 2019. Nineteen pronotal and scutellar macular patterns in addition to fifteen patterns of abdominal sternal variation in the color variation and size of the stridulatory area in D. silphoides adult were reported for the first time. In addition, the variation was observed in the shape, size and placement of eggs masses on Dodonaea viscosa commonly called 'sticky hop bush'. The main morphological features and an identification key for the five nymphal instars of this species are also provided for the first time through this work. The proportions of antennal and rostral segments and the degree of scutellum and wing pad development provide excellent characters for distinguishing the five nymphal instars. This work forms a basis for further investigation of such diversity at the molecular level and provides an insight into this phenomenon in the fascinating insect world.
Chagas disease is an important vector-borne disease endemic in Mexico. Of the 33 triatomine species found in Mexico, Triatoma longipennis (Usinger) is considered among the most important because of its infection indices, capacity for transmitting Trypanosoma cruzi (Chagas), and its distribution areas. Here, we describe the results of a reproductive isolation analysis among 5 populations of T. longipennis collected from representative areas of Mexico. Fertility and segregation of morphological characteristics were examined in two generations of hybrids. The percentage of pairs with (fertile) offspring varied from 30% to 100% in the parental crosses, while these values varied from 0 to 100% in the intersite crosses. Our results indicate partial reproductive isolation among these populations. These findings shed light on the potential presence of a cryptic species complex of T. longipennis in Mexico.
We examined the degree of reproductive isolation in four populations of Triatoma mexicana Herrich-Schaeffer from Mexico along with fertility and the segregation of morphological characteristics in two generations of offspring from crosses between these populations. The percentage of couples with (fertile) offspring was high among all sets of crosses between cohorts from Peñamiller, Meztitlán, and Orizabita. It was low in crosses involving a cohort from Tierra Blanca, mainly in crosses with Meztitlán. Among sets of crosses involving Tierra Blanca specimens, whole first-generation (F1) individuals were morphologically similar to the specimens from other locations. All F1 individuals of crosses involving Peñamiller looked like Peñamiller. However, in crosses between F1 and F1 progeny of parental crosses, alleles for size, overall color, length of head, ante and post ocular distance, and humeral angle apparently had Mendelian dominant/recessive relationships. The cohorts from Peñamiller and Meztitlán seemed to be dominant with respect to Orizabita and Tierra Blanca. Results indicated that cohorts from Peñamiller, Meztitlán, and Orizabita were not reproductively isolated. In contrast, Tierra Blanca was reproductively isolated from the other three populations of T. mexicana and is apparently undergoing an early divergence process of speciation for allopatry.
Triatoma rubrovaria subcomplex consists of T. carcavalloi, T. circummaculata, T. klugi, T. limai, T. oliveirai, T. pintodiasi, T. rubrovaria, T. patagonica, and T. guasayana, which can be vectors of Trypanosoma cruzi, the etiologic agent of Chagas disease. In this study, morphological, morphometric, and genetic characters of T. circummaculata, T. pintodiasi, T. carcavalloi, T. klugi, and T. rubrovaria were analyzed in view of the integrative taxonomy and phylogeny of the T. rubrovaria subcomplex. Molecular studies were carried out through the sequencing and analysis of the mitochondrial genes COI and CytB, nuclear genes ITS I, ITS 2, 16S, and 28S from rDNA and rescued a monophyletic group. Furthermore, differential morphological characters were found among the five species in the pronotum, scutellum, stridulatory sulcus, and external female genitalia. Finally, morphometric analyses made it possible to differentiate the five species. Phylogenetic analyzes rescued the relationship of T. pintodiasi with members of the T. rubrovaria subcomplex and demonstrated that this subcomplex is a monophyletic group composed of the species T. carcavalloi, T. circummaculata, T. klugi, T. guasayana, T. limai, T. oliveirai, T. patagonica, T. pintodiasi, and T. rubrovaria. Furthermore, through integrative taxonomy, it was possible to confirm the specific status of the species T. carcavalloi, T. circummaculata, T. pintodiasi, T. kluge, and T. rubrovaria, offering new useful morphological characters for the differentiation and characterization of these potential vectors and distributed in Southern Brazil.
