Animal: Tityus spp., with the focus on medically important species

Genus with around 230 species. The following species are considered dangerous:

Species

Taxonomy

Common names

Distribution

From Costa Rica south to northern Argentina. West Indies.

Tityus spp.

Distribution on species level:

• Tityus apiacas: Northwestern Brazil
• Tityus argentinus: Bolivia, Northern Argentina
• Tityus asthenes: Costa Rica, Colombia
• Tityus bahiensis: Southern and southeast Brazil and northern Argentina (Misiones) 
• Tityus bolivianus: Bolivia
• Tityus breweri: Eastern Venezuela (Parque Nacional Canaima)
• Tityus cambridgei: Brazil (Amazonas) and the Guyanas
• Tityus cerroazul: Costarica, Panama, Ecuador
• Tityus championi: Southern Costarica, ? Western Panama
• Tityus cisandinus: Ecuador
• Tityus confluens: Argentina, Bolivia, Paraguay and Brazil
• Tityus costatus: Southern Brazil
• Tityus dedoslargos: Southern and Eastern Brazil
• Tityus discrepans: Venezuela
• Tityus ecuadorensis: Ecuador
• Tityus falconensis: Northern Venezuela
• Tityus fasciolatus: Eastern Brazil
• Tityus festae: Eastern Panama, Northern Colombia
• Tityus fuhrmannii: Colombia
• Tityus isabelceciliae: Northern Venezuela
• Tityus metuendus: Colombia, Ecuador, Peru, Brazil, Guyana, Suriname
• Tityus neoespartanus: Isla de Margaritha (Venezuela)
• Tityus nororientalis: Eastern Venezuela
• Tityus obscurus: Northeastern Brazil, Frech Guyana
• Tityus pachyurus: Costa Rica, Colombia
• Tityus perijanensis: Colombian/Venzuelan border (Perijá range)
• Tityus pugilator: Northern Ecuador
• Tityus pusillus: Brazil
• Tityus serrulatus: Southeast Brazil, spreading to the North and West of Brazil 
• Tityus silvestris: Peru, Bolivia, Northern and eastern Brazil, Guyana, Suriname, French Guyna
• Tityus simonsi: Southern Ecuador, Northern Brazil
• Tityus soratensis: Western Bolivia
• Tityus stigmurus: Northeast Brazil 
• Tityus trinitatis: Venezuela and Trinidad  
• Tityus trivittatus: Southeastern Brazil, northern Argentina, Paraguay and Uruguay
• Tityus zulianus: Venezuela

Biology

The spiecies diversity is highest in Northern South America, mainly in the Amazon baisin, where nearly half of the Tityus species are represented.

Slender pincers. Body length of T. bahiensis, T. serrulatus, T. stigmurus and T. trivittatus up to around 7 cm, T. trinitatis up to around 9 cm.

Colouring: T. serrulatus yellowish to dark brown, legs and tail in lighter shades of yellow. T. bahiensis uniformly brown, tail and legs reddish-brown. T. trinitatis yellow-brown to dark brown, legs and pedipalps reddish and yellow.

Members of this genus can be found under stones, dead wood, loose bark or along the banks of rivers. T. bahiensis and T. serrulatus in particular commonly live in dark crevices in and around human habitations. They are also often found in large numbers in older areas of cities. Preferred habitats of T. trinitatis in Trinidad are sugar cane and coconut plantations. This species generally does not enter houses.

T. serrulatus, T. columbianus, T. metuendus, T. stigmurus, T. trivittatus and T. uruguayensis display a biological peculiarity, in that they reproduce parthenogenetically; only female animals have been found to date(Matthiesen 1962, Lourenco 2008a). Besides these there are 5 other species of scorpions that are known to reproduceparthenogenetically.

T. serrulatus is very sucessfull in spreading into new ecological settings and to displace other species like T. bahiensis; it seems that climate change does even accelerate this process (oral communication Fan Hui Wen, 2019). This is surprising, since genetic diversity is very homogenous in parthenogenetic species and thus very vulnerable against ecological changes and pressure from other species reproducing sexually.

Risk

Many Tityus species only cause local symptoms. However, severe cases of scorpion envenoming in Lower Central and South America are almost always caused by stings from members of the Tityus genus. Fatalities are attributed to various species from Lower Central America, Northern South America and Amazonia (Borges et al. 2020). Apart from Mexico, this region is known for the highest incident rate of scorpionism in the Americas.

The most dangerous species are T. serrulatus in Brazil and T. trinitatis in Trinidad. T. trivittatus and T. bahiensis only rarely cause systemic envenoming (Bücherl 1971a). T. stigmurus has been held responsible for cases of severe envenoming in the northeast of Brazil (von Eickstedt 1983/84). T. asthenes, T. fuhrmanni and T. pachyurus have been held responsible for moderate to severe, life-threatening envenoming in Colombia (Gomez and Otero 2007). Besides severe Tityus envenoming cases have been reported from Costa Rica, Panama, Trinidad and Tobago, French Guiana, Guyana, Venezuela, Ecuador, Peru and Argentina (Borges and Graham 2016).

Watermann (1938) reported 698 scorpion stings in Trinidad that were recorded in a single hospital during the period 1929–1933. The mortality rate in children under 5 years was 25%. Scorpion stings (T. trinitatis) are the most common cause of pancreatitis in Trinidad (Bartholomew 1970).

In Brazil, scorpion stings are a common cause of accidents with venomous animals. Magalhaes (1938) investigated 985 scorpion stings from Belo Horizonte, Minas Gerais: 130 patients died as a result of their sting. The highest incidence of stings occurred in the summer months of November and December. According to Bücherl (1971a) the mortality rate following envenoming by T. serrulatus is 0.8–1.4% in adults, 3–5% in school children and 15–20% in infants and young children. Between 1954 and 1965, 1,277 patients from the area around São Paulo were treated for scorpion stings at the Vital Brazil hospital. Of this number, a total of 701 cases, including 2 fatalities, were caused by T. bahiensis (Bücherl 1978). According to an epidemiological study from the southern Brazilian state of Santa Catarina, T. serrulatus and T. bahiensis stings are relatively uncommon there. In most cases no specific treatment is necessary (Bub 1993). In a more recent publication, De Albuquerque et al. (2009) suggest that Tityus pusillus may be a potentially dangerous species in the east of Brazil. In 2001 scorpion deaths equalled snakebite death In Brazil, but up to 2017 scorpion mortality increased steadily, whereas snakebite mortality nearly didn't change in figures. In 2017 most of the fatal cases in Brazil seem to be caused by T. serrulatus (oral communication Fan Hui Wen, 2019).

In Venezuela T. zulianus is claimed for fatal stings and T. discrepans and T. perijanensisi for systemic envenoming (Borges et al. 2004).

T. trivittatus is a frequent cause of scorpion stings in Argentina, but it has been reported that envenoming is generally restricted to local symptoms and transient indisposition (Abalos 1963). However, a more recent publication from Argentina reports the occurrence of regular, dangerous and sometimes fatal scorpion stings due to T. bahiensis, T. trivittatus and T. confluens (De Roodt et al. 2009).

Literature (biological)

Chippaux and Goyffon 2008, Borges 2004 and 2015, Borges and Graham 2016, Borges et al. 2020, Bücherl 1971a, 1978, Fet et al. 2000, Franke and Stockwell 1987, Keegan 1980

The Scorpion Files

iNaturalist