On the Biodiversity, Toxinology, and Public Health Impact of Scorpions in Ecuador

1. Introduction

Scorpions are ancient arthropod predators that utilize chemically complex venoms to overpower their prey, primarily insects and other arachnids such as spiders and even scorpions [1,2,3]. Their venoms are of great ecological importance and have served as a fruitful source of biomolecular innovation [4,5]. Scorpions abound with a high biodiversity and contain ca. 3000 valid species [6], of which ca. 100, mostly belonging to the primitive family Buthidae, are considered medically important [7,8,9,10]. Several buthids have been linked to fatalities, as their venom contains highly toxic components targeting mammalian ion channels with selectivity and potency [8,11].

Scorpion stings are an important, yet overlooked public health issue [12,13]. Severe cases of scorpionism, the disease syndrome following scorpion envenoming, are frequent causes of morbidity in the global south, particularly in tropical and subtropical regions [12,14]. Globally, there are an estimated 1.2 million cases annually, with thousands of fatalities reported, especially in children and the elderly [12]. Moreover, epidemiology suggests that ca. one-third of the global human population is threatened by scorpionism. Importantly, it shares many characteristics with other conditions classified as neglected tropical diseases (NTDs) [15]. These include the disproportionate impact on economically disadvantaged communities, high incidence, and particularly inadequate public health responses. However, despite recent efforts to acknowledge the dramatic impact of scorpionism in the tropics [15] it has not yet been formally recognized as a NTD [15,16,17].

While scorpionism is widespread across the global south, several particularly affected regions are localized in Latin America [12]. One of the hotspot countries is Ecuador, which is also one of the most biodiverse countries in the world. Recent epidemiological studies of national health data have analyzed scorpionism in Ecuador across two different periods (2017-2021 and 2021- 2024), both suggesting unprecedented incidence and medical relevance of scorpion sting across the country [18,19]. This magnitude in accidents is echoed by the country’s noteworthy diversity of scorpions. To date, it houses 53 validly described species [18,20] and therefore features one of the highest scorpion alpha diversities in the Neotropics [21,22]. Hence, Ecuador takes an outstanding position as a country characterized by a high taxonomic scorpion diversity, while also being victim to the medical impediments stemming from envenoming caused by its rich scorpion fauna.

Despite the important public health repercussions that scorpionism causes in Ecuador, the topic received only little scientific attention thus far [18,19,20]. Specifically, a coherent overview and discussion on the status quo of the country’s scorpion diversity, the progress in Ecuadorian scorpion toxinology, its epidemiology and potential future avenues to battle scorpionism is missing. Thus, here we set out to fill this recalcitrant gap in the scientific literature by summarizing the current state and upcoming developments revolving around the biodiversity, and toxinology of Ecuadorian scorpions. In this framework, we follow a hierarchical approach in which we first summarize what is known about the scorpion fauna of Ecuador and introduce its major taxonomic groups. Second, we take a look at the available epidemiological data to evaluate hotspots of scorpion sting and better understand the medical picture. Lastly, we summarize the available venomic data to identify priority species for future research avenues. With that, our work fills an important gap in the literature on scorpionism in one of the most impacted countries on the continent. It therefore forms a pivotal baseline upon which future works can be built upon.

2. Endless Forms Most Beautiful: The Known Diversity of Ecuadorian Scorpions

Coherent understanding of a toxinological conundrum, such as scorpion sting, intrinsically requires an in-depth knowledge on the involved animal groups, their diversity and natural history [23,24,25]. Thus, as a starting point to our endeavor, we begin with a summary of what is known about Ecuadorian scorpion diversity and a provision of critical remarks on the available literature concern their taxonomy and biogeography. At time of writing, Ecuadorian scorpions are classified into 53 species belonging to 8 genera [18]. They are further attributed towards either of five families native to Ecuador: Bothriuridae, Buthidae, Caraboctonidae, Chactidae, and Troglotayosicidae [18]. The details and nuances of these are briefly summarized henceforth. A comprehensive summary of the Ecuadorian scorpion families, the included genera with natural history data, is provided in Table 1, however a complete species-level overview has recently been presented by Borges and colleagues [18].

2.1. Bothriuridae

The family Bothriuridae is represented by a single species, Brachistosternus pegnai Cekalovic, 1969. It belongs to the most diverse genus of the family; however, its presence in the country remains poorly documented. It was recorded from a single specimen collected in San Gabriel, Carchi province (northern Ecuador) in 1965 without further information [26,27], which raises questions about its true distribution. Historically, B. ehrenbergii was also listed for Ecuador. However, subsequent revisions excluded it from the national fauna [28].

2.2. Buthidae

Buthidae is the most diverse scorpion family of Ecuador. It currently is represented by 23 species, which reflects ca. 44% of Ecuador’s scorpion diversity on species level [18,20]. Its members are distributed across all four main geographical regions (Insular, Coast, Andes, and the Amazon) and are placed in either of the three genera Ananteris, Centruroides or Tityus.

The genus Ananteris is represented with three species which are recorded from all three continental regions of Ecuador (but just four provinces Morona Santiago, Los Ríos, Pichincha, Manabí) [29,30,31]. However, the information about their distribution remains fragmented. A review of citizen-science data deposited to iNaturalist platform suggests that their distribution may extend into several Andean (Azuay, Cotopaxi, Imbabura) and Amazon provinces (Orellana, Pastaza and Zamora Chinchipe). Recently, Ythier [32] elevated Ananterinae to family level, including Ananteris as one of their genera. However, Prendini [33] maintains the genus as part of the family Buthidae. Here we follow the latest taxonomic remarks and consider the subfamily as a junior synonym of Isometrinae from Buthidae.

Centruroides is the genus whose members are the most abundant scorpion group in the coastal region, where they are responsible for the majority of envenomation cases [34,35]. Its distribution has been documented across most coastal provinces, except for Esmeraldas and El Oro. Further, records from the Andean province of Loja are available [36]. In addition, citizen- science data from the iNaturalist platform suggested occurrences in Esmeraldas, El Oro, and Azuay. Upon reviewing these records, the identification from Esmeraldas was confirmed, whereas the others could not be validated due to poor-quality photographs or obscured geographic coordinates. Records from iNaturalist were filtered based on identification status, and each observation was individually assessed to corroborate the reliability of the taxonomic assignment. In some cases, identifications were provided directly by scorpion specialists and supported by a Research Grade status. However, these data suggest a broader distribution of Centruroides than previously acknowledged, which seems to extend beyond the Coast region.

Lastly, Tityus is the most diverse scorpion genus native to Ecuador. Currently, 17 species are recognized [18] and consequently this genus alone accounts for one-third of all known Ecuadorian scorpion species. This species diversity is reflected in the genus wide distribution across the country [37]. It is known to occur across the Coast, Andes, and the Amazon regions and to be responsible for the majority of envenomation cases [18,20].

2.3. Caraboctonidae

This family is present in the country with eight species, all belonging to the genus Hadruroides [20,38]. They are present in the Insular, Coast, and the Andes [39]. It has been repeatedly thought that various specimens from this group are misidentified across the literature, but these claims were never further investigated [20].

2.4. Chactidae

In Ecuador, the family Chactidae is represented by two genera: Chactas and Teuthraustes [18,20]. It is the second most diverse family of scorpions in the country, currently housing 18 species [40]. The family is known to occur in the three continental regions: Coast, Andes, and Amazon [40,41,42].

The genus Chactas remains poorly understood on behalf of diversity and distribution with three species in the country and records restricted to four provinces (Morona Santiago, Pichincha, Napo, Sucumbíos) from the Andes and Amazon regions [41]. Similarly, limited data is available on its ecology, distribution, or medical relevance. In contrast to Chactas, Teuthraustes is well-known and better studied. The genus abounds with 15 species, rendering it the second most diverse genus in the country [40]. They occur often synanthropic and colonize urban and semi urban areas, causing a high frequency of encounters with humans [20,40]. Hence, members of Teuthraustes are suspected to cause the majority of scorpion stings in the Andes.

2.5. Troglotayosicidae

This family is currently represented by three species, all belonging to the genus Troglotayosicus [29,43,44]. Initially, the genus was described with a single record found in a cave [29] and thus its distribution was restricted to this underground habitat. However, subsequent studies revealed that its members were also present outside caves and inhabit the vegetation and leaf litter [43,44,45]. In Ecuador, their distribution is limited to the Amazon region, although records from the western slopes of the Colombian Andes suggest the possibility of additional, yet undiscovered populations within Ecuadorian territory [46]. Their morphological adaptations to lightless cave environments (e.g., absence of median eyes) raise intriguing questions about their evolutionary history.

3. Towards Integrative Thinking in Ecuadorian Scorpion Biodiversity Research

Our exploration into the biodiversity of Ecuadorian scorpions and the accompanying literature on their taxonomy, distribution, and natural history unveiled a large realm of knowledge dispersed across several important works [18,20,37,39,40,47]. However, it became subsequently clear that an array of persistent blind spots and recalcitrant mysteries have never been convincingly solved.

Thus, overall, the scorpion fauna of Ecuador remains far from fully understood in terms of its true diversity or its underlying evolutionary systematics. All across the literature, species descriptions have relied mainly on morphological characters [37,39,40]. Although morphological data is per se a useful, and historically important, component for arachnid alpha-taxonomy, it has recently been recognized as being of limited reliability [48,49,50]. In arachnids, this is due to sometimes restricted levels of information yielded from analyzed characters, as well as through morphological homoplasy amongst other effects [51,52]. In addition, distribution data, although of pivotal importance, is often poorly reported, if provided at all [26,53,54]. Likewise, the important accounts on scorpion natural history are placed in the “grey literature”, sometimes not in English language, and therefore often both, difficult to find and to interpret [55,56,57]. Since the medical importance of scorpions stems from their venom and because venom is a functional trait for hunting and defense, it evolves under constraints imposed by natural history aspects [8,25,58]. Therefore, understanding scorpion venom, including its clinically manifestations, directly builds on a coherent knowledge of a species’ natural history. In this light, the widespread and difficulty finding nature of many natural history reports is unfortunate. Lastly, many taxonomic descriptions are written vaguely and are poorly illustrated. All these factors have influenced Ecuadorian scorpion biodiversity research and owed to their detrimental nature, leaving many aspects open to future validation and reapproval.

The consequences of the above are best outlined using the genus Tityus as an example. Phenotypically, Tityus spp. are highly diverse and widely distributed (see Table 1), varying in size and exhibiting a wide range of coloration patterns (Figure 2) [37,59]. This variability, combined with quite uninformative diagnostic traits, has complicated their identification and taxonomic classification as discussed above [59]. In a pioneering study, molecular data helped to clarify the status of some species of this group previously thought to represent T. asthenes [60]. This species was thought to be present on both the west and east sides of the Andes Mountain system. However, phylogenetics analysis using molecular markers (COI, 16S), from three specimens, revealed that the scorpions inhabiting the east side on the amazon (Macuma, Morona Santiago) belonged to a different new species described as T. cisandinus (related to T. obscurus from Brazil) and at that time the species inhabiting the northwestern side of the Andes was related to T. asthenes [47,60]. Later, specimens collected in the Coast were assigned to T. rosenbergi [18,61]. In the case of the amazon region, the presence of T. cisandinus using molecular data has been confirmed from just one locality [47]. However, in all other provinces the presence of morphologically similar scorpions to T. cisandinus has been registered. This could be reminiscent of what has been reported from T. obscurus, where it has been shown that at least two morphologically very similar species are hidden within the T. obscurus taxon [62]. Hence, complementing the available taxonomic toolkit with molecular methods already clarified the identity for several members of this genus. At time of writing Tityus ranks as the most diverse scorpion genus of Ecuador (i.e. it houses a third of the countries scorpion diversity). However, based on the insights stemming from molecular works, these metrics likely represent an underestimation and the true diversity of Ecuadorian Tityus and, likewise that of other scorpion genera, remains to be revealed [37,63]. When discussing scorpion biodiversity, it is important to recognize that the conservation status of most described species remains unknown. Recently, increasing attention has been drawn to the neglect of scorpions in conservation initiatives [64]. Not only are they underrepresented on the IUCN Red List, but the impacts of deformation, urbanization, and climate chance on the population status of different species have received little to no attention.

Considering the above, it becomes evident that understanding the diversity, distribution and biology of Ecuadorian scorpions will require a more integrative approach. It is important that arachnologists from diverse methodological backgrounds and schools of thought embark on concerted efforts to unveil these aspects. This particularly includes the detailed documentation of scorpion natural history and their publication in suitable outlets, the establishment of meticulously curated collections with a large variety of specimens with precise collection data, and especially the more frequent utilization of molecular data on sufficiently large sample sizes. It may further be fruitful to increase the usage of scorpion-specific databases, such as the recently founded ScorpDB [65], and thereby support the growth of peer group created and curated public repositories.

4. Understanding and Fighting the Burden of Scorpionism Across Ecuador

Although scorpionism has historically been a neglected health issue in Ecuador and across the region, since 2016 publicly available records have begun compiling national case data [66]. However, it was not until 2021 that scorpion stings were reported as a distinct category (T63.2) in national epidemiological gazettes, alongside other toxic effects. Prior to this, reported cases were only included within a general summary table of toxicological conditions, similar to the reporting format used for national snakebite envenomation. The information compiled in these public gazettes represents a pivotal source for understanding the epidemiology of scorpionism and provides essential evidence for the development of public health programs aimed at addressing its impact in Ecuador.

In that framework, there have been two major attempts towards describing the epidemiology of scorpionism across Ecuador: the first work analyzed the data from 2017 to 2021, and reported 1514 cases resulting in 20 fatalities [18]. During this period, out of the total number of registered fatalities, 15 (75%) occurred among children from 1 to 8 years, while the remainder occurred among adults aged 20 to 81. A second study analyzed data from 2021 to 2024 and recorded a total of 1633 cases leading to five fatalities (one male and four female victims) [19]. In terms of geographic differences, both studies identified Morona Santiago as the most affected province. Specifically, this province was found to account between 35.5% and 40% of stings, respectively. Although Morona Santiago emerged as the hotspot of Ecuador’s scorpion sting burden in terms of incidence, other regions were also heavily affected. Especially the work of Borges and colleagues (2026) unveiled a high fatality rate across the western provinces, such as Esmeraldas and Santo Domingo de los Tsáchilas. To gather a better understanding of the scorpion sting epidemiology, we set out to supplement the existing studies with an own assessment of public health data. Thus, we systematically reviewed the publicly available national epidemiological gazettes on toxic effects published by the Ecuadorian Ministry of Public Health [66]. Each available weekly gazettes were examined individually, covering all available epidemiological weeks of a calendar year, and the reported number of scorpion sting cases was extracted. Because not all weekly gazettes were publicly available, some epidemiological weeks could not be assessed. Nevertheless, sufficient information was available to compile annual case totals for the period 2016-2025. Between 2016 and 2025, a total of 3,730 scorpion sting cases are reported in the analyzed sources, see Table 2. The annual number of reported cases increased from 161 in 2016 to 546 in 2025, corresponding to an approximately 239% increase over the study period. Taken together, both past studies as well as our own survey suggest, i) that incidence is high and some scorpion sting hotspots are present across Ecuador, but ii) that a vast majority of its regions are affected by scorpion sting and iii) that lethal envenoming can be recorded across the country. Moreover, the cases reported in national epidemiological gazettes likely underestimate the actual number of people stung by scorpions nationwide, highlighting a significant gap in surveillance and reporting. The underreporting is not unique to our country but mirrors similar issues seen in other South American nations, such as Brazil, and is also present with other neglected tropical diseases like snakebites [67,68]. The problem extends beyond data inaccuracies, reflecting broader structural challenges: limited access to healthcare facilities, barriers to timely medical attention, and insufficient investment in public health infrastructure. National data further reveal that the high incidence rates occur in rural provinces where communities face considerable socioeconomical disadvantages and poverty [60,69,70]. This context perpetuates cycles of underreporting and inadequate care, ultimately exacerbating the public health burden.

Besides understanding its extent, the medical care of patients is another component in the battle against scorpionism. In order to facilitate medical care of patients, rigorously peer reviewed reports of sting incidents and their treatment are important [18,19,71]. However, the literature on this matter is scarce for Ecuador. To date, only five case reports on scorpion sting envenomation have been published [60,69,70,72,73], of which four have included a detailed description of the symptoms (Table 2). They reported the following common symptoms: pain, nausea, vomiting, excessive salivation, abdominal distension, sweating, altered mental status, somnolence, abnormal lung sounds, reduced oxygen saturation, increased heart rate, high blood sugar, low blood pressure, elevated white blood cell and platelet count and altered heart and lung function. Across the 162 reported cases in these five studies, most appeared to be caused by T. rosenbergi (previously identified as T. asthenes) in the Coastal region and T. cisandinus in the Amazon. Because scorpion sting envenomation cases are understudied globally, the classification of the clinical aspects were not universally accepted nor defined until 2011 [74]. Based on this work, the categories are defined as: Class I (Local manifestations), Class II (Minor manifestations -nonlife threatening), Class II (Minor manifestations non-life threatening), and death as a separate category. Of the totality of published cases, the 54.93% (n=89) were classified as Class I, 31.48% (n=51) to Class II and 13.58% (n=22) to Class III. Most Class III cases were referred to the nearest secondary or tertiary care health centers, as primary care health centers are not supplied to attend more specific or severe cases.

It is important to note that Ecuador has a national clinical guideline for the management of snakebite envenoming and scorpion sting [75]. However, the severity classification proposed in this guideline differs from the internationally recognized categorization established in 2011. The Ecuadorian guideline defines four clinical severity categories: Grade I, characterized by local effects and mild pain; Grade II, by psychomotor agitation, anxiety, mild to moderate pain; Grade III, by acute pulmonary edema, hypotension, cardiogenic shock, severe neuromuscular excitation; and Grade IV, by multiple organ failure, seizures, and target-organ damage.

Scorpion sting is commonly treated symptomatically; however severe cases may require antivenom as a life-saving therapeutic option [76]. That said, in the past, no antivenom has been available in Ecuador, neither locally produced nor imported by the government. Efforts to provide and ensure access to antivenom for scorpion sting victims have been limited and scarce. To our knowledge, only one reported case involved the use of an antivenom (AlacramynVR, Instituto Bioclon S.A., Mexico City, Mexico) [72], yet the patient, a 4-month-old male, did not survive. However, the fatality was not attributed solely to the inefficacy of the antivenom, but also by its delayed administration and insufficient supply. Recently, following public controversy over the fatal case of a child in Taisha, Morona Santiago in the amazon region, the Ministry of Health imported a limited quantity of antivenoms of Peruvian, Brazilian, and Argentinian origin, and distributed them to centers in Cuenca, Quito, Morona, and Taisha [77].

It is important to note that antivenom efficacy is determined by the presence of antigens (i.e. the toxins) present in the venoms used for antivenom production [78,79]. Hence, although some degree of para-specificity may occur, antivenoms function well against venoms from species used in the immunization for antibody generation [80]. In others, the efficacy often is depleted, or the antivenoms are fully dysfunctional [58]. In context of the recently imported antivenoms, it must be highlighted, that antivenoms produced in Brazil are primarily developed for envenomation by T. serrulatus [81]. In Peru, there is no local production; instead, a collaborative relationship with Instituto Butantan provides access to the same Brazilian antivenom [82]. In Argentina, antivenom is produced specifically for T. carrilloi [83]. Facing the absence of Ecuadorian species, such as T. rosenbergi and T. cisandinus from the production line of the imported antivenoms, it remains questionable if these are sufficient to treat envenoming across Ecuador. Testing, and very likely optimizing, these products against venoms of Ecuadorian origin is therefore an important future task [58,72].

5. The Toxinology of Ecuadorian Scorpions

The active principles within a venom, the toxins, are the causative agents of envenoming symptoms [84]. Therefore, besides understanding the animal diversity of a venomous lineage, its epidemiological impacts and treatment, a holistic discussion on clinical consequences and threat potential, requires a toxinological perspective. Hence, in the following, we will focus on what is known about the toxin arsenal of the scorpions of Ecuador.

While venom analyses of small arthropods, including many scorpions, have historically been hampered by methodological limitations [85,86,87] the recent rise of systems biology, imaging, and biotechnological methods for the study of venom systems accelerated venom research in an unprecedented manner [88,89,90,91]. These “venomics” approaches now allow for the rapid analyses of virtually any venom system, and, consequently, they have been extensively applied to study neotropical scorpion venoms [92,93,94]. That said, venomic analyses have seen little use towards Ecuadorian species. Only recently, the medically important T. cisandinus has been studied via venom gland transcriptomics and subsequent MALDI-TOF mass spectrometry fingerprinting [95]. This work revealed a venom profile dominated by neurotoxins putatively targeting the central nervous system, many of which may target potassium and sodium channels. In total, it contained 94 components of which 60 were annotated as neurotoxins and five lipolytic beta subunits [95]. The remainder was found to resemble enzymatic components, which recently have been identified as important venom constituents in arachnid venoms [96,97,98,99]. Most of these belonged to metalloproteases (25), followed by disulfide isomerases (5), amidating enzymes (3), and one hyaluronidase [95]. Besides this pioneering work, we are unaware of any further venomic analyses carried out on an Ecuadorian species and published in peer-reviewed outlets (yet, some non-peer-reviewed work has been carried out on Teuthraustes atramentarius from Pichincha [100] and Teuthraustes sp. from Tungurahua [101]). Some further species occurring in Ecuador, e.g. Centruroides margaritatus and C. gracilis have been analyzed via venomics and some individual toxins have been isolated and characterized, yet the samples were retrieved from other countries [102,103,104]. Since venom variation is known to occur in various arachnids, especially in scorpions [105,106,107,108], it remains unclear whether these works from distinct regions are representative of Ecuadorian conspecifics. While these works may serve as rough approximation of the toxin landscape in their Ecuadorian counterparts, it will be pivotal to study individuals from across Ecuador to paint a coherent picture on their venoms.

Overall, despite their large biodiversity, their medical importance, and the urgent need for in-depth toxinological data to foster medical care, little is known about the venoms from the Ecuadorian scorpion fauna (Table 3). This features a major obstacle, because the toxins present in a venom determine the emerging symptoms and knowledge of toxin landscapes is pivotal to promote proper treatment [109]. Moreover, knowledge about venom chemistry is important for the development of novels, or the repurposing of already existing, antivenoms. Therefore, we conclude that, to battle the negative consequences imposed by scorpion sting effectively across Ecuador, concerted efforts are needed to carry out venomic profiling across the medically relevant taxa.

6. Research Priorities for Combating Scorpionism in Ecuador

The available evidence reviewed herein reveals a paradoxical situation. Ecuador ranks among the most diverse countries for scorpions in the Neotropics and simultaneously experiences a substantial burden of scorpionism [18,19]. Yet, despite this evident medical relevance, knowledge on Ecuadorian scorpions remains remarkably fragmentary. Consequently, several priority areas emerge that should be addressed in future research efforts.

First, as we discussed earlier, the Ecuadorian scorpion fauna is in urgent need for integrative biodiversity assessments. Although 53 species are currently recognized [18,20], many taxa remain poorly known, are represented by few specimens, or have distributions that are insufficiently documented. In particular, the medically important genus Tityus presents considerable taxonomic challenges and likely harbors additional undescribed diversity. Integrative approaches will therefore be essential to establish a robust taxonomic framework upon which future medical and toxinological studies can build.

Second, the epidemiology of scorpionism in Ecuador requires further refinement. Although recent nationwide analyses have considerably improved our understanding of the spatial distribution of sting incidents [18,19], discrepancies between available data sources, likely underreporting, and the scarcity of detailed clinical records continue to hinder accurate assessments of disease burden. Future efforts should focus on strengthening surveillance systems, implementing standardized reporting protocols, and improving documentation of clinical manifestations. Such initiatives would provide a more realistic estimate of the public health impact of scorpionism and facilitate evidence-based decision making.

Third, the suitability of currently available antivenoms remains largely unknown. Ecuador currently lacks local antivenom production and relies on imported products developed against non-Ecuadorian scorpion species. Given the known diversity of venoms within the genus Tityus alone and the demonstrated importance of venom composition for antivenom efficacy, systematic assessments of cross-neutralization capacity should be considered a priority. Such studies are essential to determine whether currently available antivenoms provide adequate protection against envenoming by Ecuadorian species and to guide future therapeutic strategies. That said, on the long term it would be desirable to initiate local antivenom production in Ecuador.

Finally, the most severe knowledge gap concerns the venoms themselves. At present, T. cisandinus remains the only Ecuadorian scorpion species that has been subjected to modern venomic investigations (e.g., Borges & Román, 2023; Kalapothakis et al., 2023; Román et al., 2018). Consequently, virtually nothing is known about the toxin composition, functional activities, or evolutionary diversification of the venoms from most Ecuadorian scorpions. Future research should therefore prioritize medically important taxa, particularly T. cisandinus and T. rosenbergi, which are currently associated with the majority of severe and fatal envenomation cases [60,72,111]. Additional attention should be directed towards other members of the subgenus Atreus, including T. forcipula, T. crassicauda, T. timendus, and T. ythieri, whose phylogenetic relationships suggest a potential for medically significant venoms [8,20]. Beyond species-level surveys, future studies should investigate venom variation across populations, sexes, and life-history stages, as such patterns are increasingly recognized as important drivers of venom evolution but remain underexplored in scorpions.

Taken together, addressing these priorities will require close collaboration between taxonomists, ecologists, toxinologists, clinicians, and public health authorities. Such integrative efforts are essential not only to advance our understanding of Ecuadorian scorpions but ultimately to reduce the burden of scorpionism and improve patient care across the country.

Conclusions

Scorpion sting represents a global health burden, theoretically threatening one-third of the global human population, and is especially prevalent in the global south. Ecuador, one of earths most biodiverse countries, also ranks among the most speciose countries in terms of scorpion diversity. That said, the high diversity and abundance of scorpions correlate with a high frequency of human-scorpion interactions, resulting in numerous cases of scorpionism every year. Hence, scorpion sting is a major public health issue in Ecuador, yet the problem received little scientific attention thus far.

Here, we provide a synthesis of the available scientific literature alongside a discussion of persistent obstacles and needed future developments on three major aspects of Ecuadorian scorpion sting: i) the diversity and natural history of scorpions, ii) the epidemiology and medical care, and iii) their toxinology. In our assessment, we deliver a complete overview of the Ecuadorian scorpion fauna. That said, our analysis revealed, that taxonomic assessments are suffering from various hurdles, often resulting in an unclear picture of species diversity, their lifestyles, and distribution ranges. We argue that future assessments based on integrative approaches are needed to unveil which species occur throughout the country and to understand their life history. This could be used to mitigate sting accidents or to develop precise distribution maps and identification keys to help physicians. In terms of epidemiology, we found that especially the province Morona Santiago represents a hotspot of scorpion sting, but various other regions are likewise affected, and fatalities can occur all across the country. While every year, hundreds of stings are detected, it is likely that available metrics feature a sever underestimation, because many parts of the country lack proper medical infrastructure, and many cases remain likely unrecorded. This is especially unfortunate, as children are at risk of lethal envenoming, which adds a particularly dreadful note to the problem. While antivenom, the only effective treatment for most envenoming, would be desirable, no antivenom is produced in Ecuador, and foreign products are only rarely imported. That said, the efficacy of these imports remains to be validated. Lastly, in terms of toxinology, we found that virtually nothing is known about the venom profile of Ecuadorian scorpions and only one species (T. cisandinus) has really been studied thus far. This renders venomic surveys across the Ecuadorian scorpion fauna as an important future step, as a coherent understanding of venom chemistry and activity is important to optimize medical care and guide both, antivenom production and application of foreign products.

In our work, we summarize what is known about the biodiversity, medical importance and toxinology of Ecuadorian scorpions and thereby add a needed overview on the matter of scorpion sting in one of the most affected countries of the New World. By building on two previous studies and incorporating updated and new data, our work advances current knowledge and provides an important foundation for future research in the identified priority areas.