First report of the medically significant scorpion Tityus carrilloi in Paraguay

 

As stated in earlier posts, medical important scorpions are expanding their distribution in many parts of South America. Adolfo Borges and co-workers have recently reported the findings of the medical important species Tityus carrilloi Ojanguren-Affilastro, 2021 (Buthidae) in Paraguay. This species has previously only been known from Argentina where it has been involved in severe and fatal envenomations.

Abstract:
We report the first record of the medically important scorpion Tityus carrilloi in Paraguay, from the metropolitan area of Encarnac ´on, Itapúa Department, near the Argentine border. Known for causing severe and fatal envenomings across northern Argentina, the presence of this species in southeastern Paraguay highlights the risk of cross-border dispersion. Along with the regional spread of the Brazilian Tityus serrulatus, this finding has significant epidemiological implications and underscores the urgent need for improved surveillance, diagnostics, and coordinated public health responses in Paraguay and neighboring countries, within the evolving landscape of scorpionism in southern South America.

Reference:
Borges A, Caballero C, Rojas de Arias A, Smith P, Owen M, Nishi A, et al. First report of the medically significant Argentine scorpion Tityus carrilloi (Buthidae) in Paraguay: Epidemiological implications amid rising regional scorpionism. Toxicon. 2025;264:108456. [Subscription required for full text]

A new medical significant Tityus species from Argentina

 

The genus Tityus C. L. Koch, 1836 (Buthidae) contains some of the most medical significant species in South America and in the world. One the the most infamous species is Tityus trivittatus Kraepelin 1898, a species known to cause death and serious morbidity in parts of Brazil, Paraguay, Uruguay and Argentina.

Andrés Alejandro Ojanguren Affilastro and co-workers have recently done a taxonomic and phylogenic study of Tityus trivittatus. Their study shows that the poplations of T. trivittatus in Argentia is acutally a separate species.

Tityus carrilloi Ojanguren Affilastro, 2021 (Argentina)

We know that the new species is medically significant because this has been documented for these populations previously (as Tityus trivittatus). The discovery of this new species is important, as the venom content of T. trivittatus and T. carrilloi vary and this may have consequences for the treatment of sting patients. 

This is an important study as knowledge about the taxonomy of venomous species is important both for treatment and prevention and control.

Abstract:
Tityus trivittatus is considered the most medically important scorpion species of southern South America. In this contribution we redefine its taxonomy, redescribe the species and separate the southern populations as a new species, Tityus carrilloi n. sp. As a consequence of this description, the most medically important species of the region turns out to be the new species herein described. We also clearly establish the phylogenetic position of both species through a dated molecular phylogenetic analysis based on four genes. Finally, we discuss the differences of the venom between the two species, and the epidemiologic implications of our results on the scorpionism problem in the region.

Reference:
Ojanguren A, Kochalka J, Orellana D, Garcete Barrett BR, Borges A, Ceccarelli F. Redefinition of the identity and phylogenetic position of Tityus trivittatus Kraepelin 1898, and description of Tityus carrilloi n. sp. (Scorpiones; Buthidae), the most medically important scorpion of southern South America. Revista del Museo Argentino de Ciencias Naturales, Nueva Serie. 2021;23:27-55. [Open Access]

Family Buthidae

Genetic and toxinological study of Tityus trivittatus from Argentina and Paraguay indicates cryptic species in Paraguay with medical importance

 

The genus Tityus C. L. Koch, 1836 (Buthidae) includes some of the most dangerous species in South America and Tityus trivittatus Kraepelin, 1898 is one of the most medically important species, causing deaths and serious morbidity especially in Argentina. 

Urban populations of Tityus trivittatus have also caused severe cases in children in Paraguay, Adolfo Borges and co-workers have published a genetic and toxinological study of the populations of T. trivittatus in Paraguay. 

Their study confirms the medical important of this scorpion in Paraguay. In addition, the study show a significant difference in the venom composition between the populations from Paraguay and Argentina. This result is probably an evidence that the two populations represent different species. Futher studies are necessary to reveal the taxonomical implications of these findings.

Abstract:
Envenoming by scorpions in genus Tityus is a public health problem in Tropical America. One of the most medically significant species is Tityus trivittatus, which is known to occur from southwest Brazil to central-northern and eastern Argentina. In this work, we studied the lethality, composition, antigenicity, and enzymatic activity of venom from a T. trivittatus population found further north in urban areas of eastern Paraguay, where it has caused serious envenomation of children. Our results indicate that the population is of medical importance as it produces a potently toxic venom with an LD50 around 1.19 mg/kg. Venom neutralization in preliminary mouse bioassays was complete when using Brazilian anti-T. serrulatus antivenom but only partial when using Argentinean anti-T. trivittatus antivenom. Venom competitive solid-phase enzyme immunoassays and immunoblotting from Argentinean and Paraguayan T. trivittatus populations indicated that antigenic differences exist across the species range. SDS-PAGE showed variations in type and relative amounts of venom proteins between T. trivitattus samples from Argentina and Paraguay. MALDI-TOF mass spectrometry indicated that while some sodium channel toxins are shared, including β-toxin Tt1g, others are population-specific. Proteolytic activity by zymography and peptide identification through nESI-MS/MS also point out that population-specific proteases may exist in T. trivitattus, which are postulated to be involved in the envenoming process. A timecalibrated molecular phylogeny of mitochondrial COI sequences revealed a significant (8.14%) genetic differentiation between the Argentinean and Paraguayan populations, which appeared to have diverged between the mid Miocene and early Pliocene. Altogether, toxinological and genetic evidence indicate that T. trivitattus populations from Paraguay and Argentina correspond to distinct, unique cryptic species, and suggest that further venom and taxonomic diversity exists in synanthropic southern South American Tityus than previously thought.

Reference:
Borges A, Rojas de Arias A, de Almeida Lima S, Lomonte B, Díaz C, Chávez-Olórtegui C, et al. Genetic and toxinological divergence among populations of Tityus trivittatus Kraepelin, 1898 (Scorpiones: Buthidae) inhabiting Paraguay and Argentina. PLoS Negl Trop Dis. 2020;14(12):e0008899. [Open Access]

Thanks to Adolfo for sending me their article!