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5. Tityus asthenes, female holotype. Habitus, dorsal and ventral aspects. Recent colour photos taken in 2017. Labels attest that the type was examined by F. Matthiesen, while in the Muséum in Paris during 1972. (Scale bar = 1 cm).
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... The approach proposed here could be instrumental for evaluating the actual distribution of the medically important western T. obscurus population, and for estimating the overall genetic structure of the T. obscurus complex, which possibly underlies the existence of diversity gradients for venom toxic and immunogenic components. In this sense, the recent finding that Tityus cisandinus (Lourenço and Ythier 2017) from Amazonian Ecuador is genetically related to T. obscurus from Brazilian Amazonia, as its envenoming syndrome also includes neurological alterations (Román et al. 2018;Borges et al. 2021). This indicates that a combined approach using clinical, phylogenetic, and toxinological tools should prove rewarding in the study of Tityus diversity in the Amazon Basin. ...
Scorpion envenoming is considered a public health problem in Brazil. A recent study described a variation in the clinical outcome of envenoming by Tityus obscurus in two populations separated by 850 km in the northeastern Amazon region. Our aim was to evaluate whether such clinical and toxinological variations are associated with underlying differences in genetic diversity between these two T. obscurus populations. We obtained DNA from five individuals of each population, in the municipalities of Belém and Santarém, located east and west of the state of Pará, Brazil, respectively. Gene regions encoding mitochondrial DNA (mtDNA) markers cytochrome oxidase subunit I (COI) and ribosomal 16S RNA (16S) were amplified and sequenced. Phylogenetic analyses were performed using maximum likelihood (ML) and Bayesian inferences (BA) for both molecular data (COI and 16S). The sampled T. obscurus populations corresponded to two distinct mtDNA lineages (genetic distance COIK2 P = 0.08 to 0.13; 16SK2 P = 0.10 to 0.11) with no shared mutations between groups and well supported by ML and BA inferences. Based on the divergence values found between eastern and western populations (COI, 0.07 to 0.12; 16S, 0.10), our study confirms the genetic heterogeneity of T. obscurus populations within the state of Pará, which correlates with observed venom and clinical differences, and reinforces the need for mapping the distribution of haplotypes throughout the geographic range of T. obscurus, to aid in future epidemiological, toxinological, and evolutionary studies.
KEYWORDS:
mitochondrial DNA; phylogenetic analyses; cytochrome oxidase subunit I; 16S RNA
... In addition, T. obscurus is responsible for the majority of stings and the most severe cases of envenomation in eastern Amazonia (Castro de Oliveira et al., 2018;Martins et al., 2023). Lourenço and Ythier (2017) called attention to the original description of T. asthenes possibly dealing with a species belonging to another subgenus, with distribution to the south of Peru, while populations referred to as T. asthenes from Colombia and Ecuador correspond to species related to dark scorpions´subgenus T. (Atreus) (from herein, we will refer to them as T. cf. asthenes). ...
... asthenes). Consequently, T. cisandinus was recently described as the species inhabiting the rainforests of the Ecuadorian Amazonia (Lourenço and Ythier, 2017). ...
... We tried to elucidate the possible differences in the venom of these three species and how it compares to the venom of T. cf. asthenes from Colombia, the type-species of the previously classified subgenus Atreus (Lourenço and Ythier, 2017;Martins et al., 2023). We also compared the data obtained with sequences from publicly available databases for T. obscurus (Brazil) and T. pachyurus (from Colombia and Panama), which are the best-characterized venoms of dark-colored Tityus (Atreus) scorpions from the region. ...
... During the ontogeny of T. obscurus, juveniles are easily confused with other scorpion species of the same subgenus (Atreus) or of a different one (ArchaeoTityus) (Lourenço, 1983). Even adult specimens of T. obscurus, especially females, exhibit high morphological similarity with other related species such as Tityus apiacas Lourenço (2002); Tityus cisandinus Lourenço and Ythier (2017); Tityus dinizi Lourenço (1997); Tityus tucurui Lourenço (1988), and Tityus unus Pinto-da-Rocha and In fact, the phenotypic traits that define Tityus species (Moreno-González et al., 2021), frequently overlap (i.e., pectinal tooth count, number of movable finger oblique rows of granules, morphometric data) and there are no clear comparative diagnoses to differentiate them. The original description of Tityus obscurus (Gervais, 1843) is brief and old, and its exact location in French Guiana was not reported (Lourenço, 2002). ...
... Recently, T. asthenes has been redescribed and transferred to the species group Tityus bolivianus. Therefore, all species formerly belonging to the species group T. asthenes have been assigned to the new species group Tityus obscurus (Lourenço and Ythier, 2017). Furthermore, a dated phylogenetic hypothesis that used COI sequences suggested that the Amazonian scorpion species included in this group (such as T. cisandinus, T. metuendus and T. obscurus) constitute a clade that diverged about 28 million years ago in the late Miocene and the Pliocene (Borges et al., 2021). ...
... This suggests that in the Amazon, scorpion venoms are potentially different from the species selected for commercial antivenom production (Kalapothakis et al., 2022;Fan et al., 2015). Brazil has a complex scorpiofauna, and some species of medical importance live in microendemic regions of the Amazon (Lourenço and Ythier, 2017). Venomous animals living in these locations can produce toxins for specific natural enemies (Zhang, 2015), and the antigens of these venoms can be partially recognized by antibodies derived from large animals (Calvete, 2017;Zhang, 2015), such as horses that are used to produce immune responses against scorpion toxins (Fan and Monteiro, 2018). ...
Tityus obscurus has caused mild, moderate and severe accidents of medical relevance in the eastern Brazilian Amazon and French Guiana. Tityus obscurus has sexual dimorphism although males and females have uniform black coloration. In the Amazon, one of the habitats of this scorpion is seasonally flooded forests (igapós and várzeas). However, most stings occur in terra firme forest areas (non-flooded region), where most rural communities are located. Adults and children stung by T. obscurus may experience an “electric shock” sensation for more than 30 h after the sting. Our data shows that people inhabiting remote forest areas, including rubber tappers, fishermen and indigenous people, with no access to anti-scorpion serum, use parts of native plants, such as seeds and leaves, against pain and vomiting caused by scorpion stings. Although there is a technical effort to produce and distribute antivenoms in the Amazon, many cases of scorpion stings are geographically unpredictable in this region, due to the lack of detailed knowledge of the natural distribution of these animals. In this manuscript, we compile information on the natural history of T. obscurus and the impact of its envenoming on human health. We identify the natural sites that host this scorpion in the Amazon, in order to warn about the risk of human envenoming. The use of specific antivenom serum is the recommended treatment for accidents involving venomous animals. However, atypical symptoms not neutralized by the available commercial antivenom are reported in the Amazon region. Facing this scenario, we present some challenges to the study of venomous animals in the Amazon rainforest and possible experimental bottlenecks and perspectives for establishing a method aimed at producing an efficient antivenom.
... Seven papers analyzed clinical manifestations after envenomation by Tityus obscurus [11,12,46,50,51,52,53] (from Pará state, Brazil, and Cayenne, French Guiana), three by T. silvestris (Pará and Amazonas states, Brazil) [8,44,45], two by T. apiacas (Amazonas state, Brazil) [8,43], and one each by T. metuendus (Amazonas state, Brazil) [8], T. raquelae (Amazonas state, Brazil) [8], T. strandi (Pará state, Brazil) [30], T. breweri (Bolívar state, Venezuela) [15], and T. cisandinus (from Morona Santiago, Ecuador) [14]. Scorpions involved in human injuries from Amazonian Ecuador reported by Roman et al. [14] which were not identified at that time, but were recently identified by one of the authors as Tityus cisandinus [54]. ...
Venom from Amazonian scorpions of the genus Tityus contains components capable of eliciting a distinct clinical, mostly neurological, syndrome. This contrasts with the mainly autonomic manifestations produced after envenomation by congeneric southern and northern South American species. Herein, we summarize Pan-Amazonian scorpionism by synthesizing available toxinological, clinical, and molecular data gathered from all affected areas in Amazonia, including Brazil, Ecuador, Colombia, Peru, Venezuela, and French Guiana. We searched multiple databases, as well as our own records, for reports of scorpion envenomations in Amazonia by confirmed Tityus spp., and compared the clinical manifestations. To help uncover clinical and venom relationships among problematic species, we explored phylogenetic relationships with a rate-calibrated analysis of mitochondrial COI data from available species. The possible existence of diversity gradients for venom toxic and immunogenic components despite the predicted strong phylogenetic association among species is underscored by discussed clinical and toxinological findings. A multicentric effort, involving all nations affected by this neglected disease, is urgently needed to offer alternatives for treating and understanding this pathology, including the preparation of neutralizing antibodies with a broad range of efficacy.
... We also obtained samples from Panama (seven locations in the provinces of Coclé, Panama, and Veraguas), Costa Rica (one location in the Limón province), and Colombia (one location in Antioquia department), for a total of 25 Tityus populations analyzed. Collecting sites for these specimens, together with those from southeast Brazil, Venezuela, and Trinidad, are listed in Table 1 and locations appear in Fig. 1 Francke and Stockwell, 1987), Brazil (Lourenço, 2002), Ecuador ( Lourenço and Ythier, 2017), Venezuela (González-Sponga, 1996), Colombia (Lourenço, 2000), andTrinidad andTobago (Kjellesvig- Waering, 1966). Specimens were kept alive at the different centers that participated in this study, fed with crickets (Acheta domesticus) and/or mealworms (Tenebrio molitor), and venom from selected populations was extracted as described below. ...
Scorpions of the Neotropical genus Tityus are responsible for most severe envenomations in the Caribbean, South America, and Lower Central America (LCA). Although Tityus is taxonomically complex, contains high toxin polymorphism, and produces variable clinical manifestations, treatment is limited to antivenoms produced against species with restricted distributions. In this study, we explored the compositional and antigenic diversity of Tityus venoms to provide improved guidelines for the use of available antivenoms at a broader geographic scale. We used immunoblotting, competitive ELISA, and in vivo studies to compare reactivity against commercial antivenoms from Brazil, Venezuela, and Mexico, as well as MALDI-TOF mass spectrometry, cDNA sequencing, and phylogenetic analyses to assess venom sodium channel-active toxin (NaTx) content from medically important Tityus populations inhabiting Brazil, Colombia, Costa Rica, Ecuador, Panama, Trinidad and Tobago, and Venezuela. Additionally, we raised rabbit antibodies against Tityus venoms from LCA to test for cross-reactivity with congeneric species. The results suggest that Tityus spp. possess high venom antigenic diversity, underlying the existence of four toxinological regions in Tropical America, based on venom composition and immunochemical criteria: LCA/Colombia/Amazonia (Region I), Venezuela (Region II), southeast South America (Region III), and a fourth region encompassing species related to toxinologically divergent Tityus cerroazul. Importantly, our molecular and cross-reactivity results highlight the need for new antivenoms against species inhabiting Region I, where scorpions may produce venoms that are not significantly reactive against available antivenoms.
... In two recent publications the status of the enigmatic buthid scorpion, Tityus asthenes Pocock, 1893 was discussed and clarified (see Lourenço & Ythier, 2017;Lourenço & Florez, 2018 for details). This led to a reconsideration of the status of several species previously considered as synonym of Tityus asthenes (Lourenço, 1988) and the identity of some populations present in both Ecuador and Colombia were clarified. ...
... Until recently, the Amazonian populations of large blackish species of Tityus (Atreus) were formerly associated to a 'Tityus asthenes group' (Lourenço, 1988;Lourenço & Ythier, 2017). ...
... However, since the true taxonomic position of the species Tityus asthenes Pocock, 1893 was recently clarified (Lourenço & Ythier, 2017), showing that the species Tityus asthenes belongs in fact to the speciesgroup of Tityus bolivianus Kraepelin, 1895 (Lourenço & Maury, 1985) it is no longer logical to maintain the definition of such a group. Instead, it seems reasonable to propose a new group for the large blackish species of Atreus presenting long and thin pedipalps. ...
In recent publications the status of the enigmatic buthid scorpion Tityus asthenes Pocock, 1893 was finally clarified leading to a revaluation of the status of several species previously associated to Tityus asthenes. Some old species were revalidated and new species described. The range of distribution of several species proved to be quite limited suggesting patterns of microendemism for several populations which are the result of past climatic vicissitudes that took place in Tropical America during the Quaternary and Late Cenozoic. In the present study, the geographic patterns of distribution presented by several Amazonian populations of Tityus (Atreus) formerly associated to the Tityus asthenes group are discussed and a new species is described from Occidental Amazonia.
Envenomation by scorpions belonging to the genus Tityus can be life threatening in the Americas, particularly in the Amazon Basin. We report a 4-month-old Ecuadorean boy of Shuar origin stung by a scorpion identified as Tityus cisandinus in the Amazonian province of Morona Santiago, presenting with pulmonary edema and systemic inflammation. We administered immunotherapy using the scorpion antivenom available in Ecuador, of Mexican origin (anti- Centruroides ). Catecholamine discharge-related events such as hyperglycemia and thrombocytosis were resolved after treatment but leukocytosis did not, suggesting that factors associated with the sting-admission delay and specificity of antivenom played a role in the envenomation outcome. Cardiorespiratory arrest determined a fatal outcome, despite specific maneuvers. The case severity and the limited supply of nonspecific scorpion antivenoms in problematic areas of Amazonian Ecuador and elsewhere in northwestern Amazonia are discussed in regard to the need for specific therapeutic immunoglobulins in the area and in the Amazon Basin as a whole.
Tityus cisandinus, a neglected medically important scorpion in Ecuadorian and Peruvian Amazonia, belongs to a complex of species related to the eastern Amazon endemic Tityus obscurus, spanning a distribution of ca. 4000 km. Despite high morbidity and mortality rates, no effective scorpion antivenom is currently available in the Amazon region. Knowledge of the structural/functional relationships between T. cisandinus venom components and those from related Amazonian species is crucial for designing region-specific therapeutic antivenoms. In this work, we carried out the first venom gland transcriptomic study of an Amazonian scorpion outside Brazil, T. cisandinus. We also fingerprinted its total venom through MALDI-TOF MS, which supported our transcriptomic findings. We identified and calculated the expression level of 94 components: 60 toxins, 25 metalloproteases, five disulfide isomerases, three amidating enzymes, one hyaluronidase, and also uncovered transcripts encoding novel lipolytic beta subunits produced by New World buthid scorpions. This study demonstrates the high similarity between T. cisandinus and T. obscurus venoms, reinforcing the existence of a neglected complex of genetically and toxinologically related Amazonian scorpions of medical importance. Finally, we demonstrated the low recognition of currently available therapeutic sera against T. cisandinus and T. obscurus venoms, and concluded that these should be improved to protect against envenomation by Amazonian Tityus spp.
The Tityus forcipula species group has had an intricate taxonomic history, changing its diagnostic characters and
composition on several occasions. One of the alleged reasons for this taxonomic uncertainty is the use of superficial
characters (i.e. raw similarity instead of putative synapomorphies) for species group delimitation. Here, we conducted a
thorough phenotypic survey across the Tityus forcipula species group, as currently delimited, including characters that
had been suggested elsewhere as putative synapomorphies for delimiting lineages within Tityus. In doing so we also
redescribe Tityus forcipula and describe a new species belonging to the Tityus forcipula species group: Tityus moralensis
sp. nov. based on specimens from the Andean region of Valle del Cauca department, Colombia. The Tityus forcipula
species group is here delimited to Andean species from Colombia and Ecuador that share strongly sclerotized and brown
colored pectines, basal middle lamellae of female pectines dilated and suboval or ovoid shaped, basal plate of female
pectines without glandular region and telotarsi with two ventrosubmedian rows (type II) of stout macrosetae (i.e., Tityus
crassicauda, Tityus cuellari, Tityus forcipula, Tityus fuhrmanni and Tityus moralensis sp. nov). The new Tityus species is
placed into a phylogenetic context with other buthid species using DNA sequences (COI and 28S). Finally, we provide a
map with updated distributional records of the Tityus forcipula species group.
