''Tityus serrulatus'', the Brazilian yellow scorpion, is a species of

scorpion Scorpions are predatory arachnids of the order Scorpiones. They have eight legs, and are easily recognized by a pair of grasping pincers and a narrow, segmented tail, often carried in a characteristic forward curve over the back and always end ...

of the family

Buthidae The Buthidae are the largest family of scorpions, containing about 100 genera and 1339 species as of 2022. A few very large genera (''Ananteris'', ''Centruroides'', '' Compsobuthus'', or '' Tityus'') are known, but a high number of species-poor o ...

. It is native to

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

, and its venom is extremely toxic. It is the most dangerous scorpion in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

and is responsible for the most fatal cases.

Description

Adult specimens typically measure between 5–7 cm (2–3 in) in length. As suggested by its common name, coloration consists of pale-yellow legs (8 in total) and

pedipalp Pedipalps (commonly shortened to palps or palpi) are the second pair of appendages of chelicerates – a group of arthropods including spiders, scorpions, horseshoe crabs, and sea spiders. The pedipalps are lateral to the chelicerae ("jaws") and ...

s, with a darker shade of yellowish brown on the trunk, fingers, and tip of the tail. Like other members of the family

, ''T. serrulatus'' has a bulbous tail, often carried in a characteristic forward curve over the back, which is segmented, with prominent ridges and serrations. The tail is tipped with a venom-injecting barb capable of immobilizing prey or delivering defensive strikes.

Geographic range

The species is endemic to Brazil and widely found throughout the country, including the states of

Alagoas Alagoas (, ) is one of the 27 federative units of Brazil and is situated in the eastern part of the Northeast Region. It borders: Pernambuco (N and NW); Sergipe (S); Bahia (SW); and the Atlantic Ocean (E). Its capital is the city of Maceió. It ...

Bahia Bahia ( , , ; meaning "bay") is one of the 26 Federative units of Brazil, states of Brazil, located in the Northeast Region, Brazil, Northeast Region of the country. It is the fourth-largest Brazilian state by population (after São Paulo (sta ...

Ceará Ceará (, pronounced locally as or ) is one of the 26 states of Brazil, located in the northeastern part of the country, on the Atlantic coast. It is the eighth-largest Brazilian State by population and the 17th by area. It is also one of the ...

Espírito Santo Espírito Santo (, , ; ) is a state in southeastern Brazil. Its capital is Vitória, and its largest city is Serra. With an extensive coastline, the state hosts some of the country's main ports, and its beaches are significant tourist attra ...

Goiás Goiás () is a Brazilian state located in the Center-West region. Goiás borders the Federal District and the states of (from north clockwise) Tocantins, Bahia, Minas Gerais, Mato Grosso do Sul and Mato Grosso. The state capital is Goiânia. ...

Mato Grosso Mato Grosso ( – lit. "Thick Bush") is one of the states of Brazil, the third largest by area, located in the Central-West region. The state has 1.66% of the Brazilian population and is responsible for 1.9% of the Brazilian GDP. Neighboring ...

Mato Grosso do Sul Mato Grosso do Sul () is one of the Midwestern states of Brazil. Neighboring Brazilian states are (from north clockwise) Mato Grosso, Goiás, Minas Gerais, São Paulo and Paraná. It also borders the countries of Paraguay, to the southwest, and ...

Minas Gerais Minas Gerais () is a state in Southeastern Brazil. It ranks as the second most populous, the third by gross domestic product (GDP), and the fourth largest by area in the country. The state's capital and largest city, Belo Horizonte (literally ...

, Paraná,

Pernambuco Pernambuco () is a state of Brazil, located in the Northeast region of the country. With an estimated population of 9.6 million people as of 2020, making it seventh-most populous state of Brazil and with around 98,148 km², being the 19 ...

Rio de Janeiro Rio de Janeiro ( , , ; literally 'River of January'), or simply Rio, is the capital of the state of the same name, Brazil's third-most populous state, and the second-most populous city in Brazil, after São Paulo. Listed by the GaWC as a b ...

Rio Grande do Norte Rio Grande do Norte (, , ) is one of the states of Brazil. It is located in the northeastern region of the country, forming the northeasternmost tip of the South American continent. The name literally translates as "Great Northern River", ref ...

Rio Grande do Sul Rio Grande do Sul (, , ; "Great River of the South") is a Federative units of Brazil, state in the South Region, Brazil, southern region of Brazil. It is the Federative_units_of_Brazil#List, fifth-most-populous state and the List of Brazilian st ...

Rondônia Rondônia () is one of the 26 states of Brazil, located in the northern subdivision of the country (central-western part). To the west is a short border with the state of Acre, to the north is the state of Amazonas, in the east is Mato Grosso, ...

, Santa Catarina,

São Paulo São Paulo (, ; Portuguese for 'Saint Paul') is the most populous city in Brazil, and is the capital of the state of São Paulo, the most populous and wealthiest Brazilian state, located in the country's Southeast Region. Listed by the GaWC a ...

Sergipe Sergipe (), officially State of Sergipe, is a state of Brazil. Located in the Northeast Region along the Atlantic coast of the country, Sergipe is the smallest state in Brazil by geographical area at , larger only than the Federal District. Serg ...

, and

Distrito Federal A federal district is a type of administrative division of a federation, usually under the direct control of a federal government and organized sometimes with a single municipal body. Federal districts often include capital districts, and they e ...

. "Due to deforestation and growing urbanization, this species is becoming more and more present," according to Rogério Bertani in an interview with the British newspaper ''

The Guardian ''The Guardian'' is a British daily newspaper. It was founded in 1821 as ''The Manchester Guardian'', and changed its name in 1959. Along with its sister papers ''The Observer'' and ''The Guardian Weekly'', ''The Guardian'' is part of the Gu ...

''. He is a scientist and scorpion specialist at the

Butantan Institute Instituto Butantan (in modern Portuguese, Instituto Butantã, ) is a Brazilian biologic research center located in Butantã, in the western part of the city of São Paulo, Brazil. Instituto Butantan is a public institution affiliated with the S� ...

in São Paulo. "I personally think that the problem will continue to grow." By 2018 there was a notable increase in the number of ''T. serrulatus'' scorpions living in the urban spaces of

, contributing to an increase in reported scorpion stings in Brazil from 12,000 in 2000 to 140,000 by 2018. An abundance of prey, notably

cockroach Cockroaches (or roaches) are a paraphyletic group of insects belonging to Blattodea, containing all members of the group except termites. About 30 cockroach species out of 4,600 are associated with human habitats. Some species are well-known as ...

es, and shelter along with a lack of predators is believed to be a cause of the increase in scorpion numbers in Brazilian cities.

Feeding

It has a diet of insects, such as cockroaches, and is suited to life in sewers and trash heaps in urban areas. Having a low metabolic rate, it can survive for months without eating.

Reproduction

The species is usually

parthenogenetic Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and development ...

Venom

Potency

In Brazil, scorpions are credited with causing the highest incidence of human envenomations of all venomous animals. They cause more than all other venomous animals, including snakes and spiders, combined. With mortality rates ranging from 1.0 to 2.0% among children and elderly persons, ''T. serrulatus'' is responsible for more medically significant accidents than any other scorpion in the country. Most stings occur in urban areas, inside or near homes, with greater frequency in the south and southeast during the warm and rainy months, but with little or no seasonal variability in the north, northeast, and center-west.

Effects

In mild cases, localized pain is the primary symptom. ''Tityus s.'' venom contains TsIV, which slows the inactivation of

sodium channel Sodium channels are integral membrane proteins that form ion channels, conducting sodium ions (Na+) through a cell's membrane. They belong to the superfamily of cation channels and can be classified according to the trigger that opens the channel ...

s in muscles and nerve cells. ''Tityus serrulatus'' has an excitatory

neurotoxin Neurotoxins are toxins that are destructive to nerve tissue (causing neurotoxicity). Neurotoxins are an extensive class of exogenous chemical neurological insultsSpencer 2000 that can adversely affect function in both developing and mature ner ...

that attacks the autonomic nervous system, causing the release of adrenaline, noradrenaline and acetylcholine, causing an immense variety of symptoms in the victims; clinical effects may include

hyperglycemia Hyperglycemia is a condition in which an excessive amount of glucose circulates in the blood plasma. This is generally a blood sugar level higher than 11.1 mmol/L (200 mg/dL), but symptoms may not start to become noticeable until even ...

, fever,

priapism Priapism is a condition in which a penis remains erect for hours in the absence of stimulation or after stimulation has ended. There are three types: ischemic (low-flow), nonischemic (high-flow), and recurrent ischemic (intermittent). Most cases ...

, agitation,

hypersalivation Hypersalivation, or ptyalism, also known as sialorrhea or hypersialosis is the excessive production of saliva. It has also been defined as increased amount of saliva in the mouth, which may also be caused by decreased clearance of saliva.Medscape ...

tachycardia Tachycardia, also called tachyarrhythmia, is a heart rate that exceeds the normal resting rate. In general, a resting heart rate over 100 beats per minute is accepted as tachycardia in adults. Heart rates above the resting rate may be normal (su ...

hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...

mydriasis Mydriasis is the dilation of the pupil, usually having a non-physiological cause, or sometimes a physiological pupillary response. Non-physiological causes of mydriasis include disease, trauma, or the use of certain types of drugs. Normally, as ...

sweating Perspiration, also known as sweating, is the production of fluids secreted by the sweat glands in the skin of mammals. Two types of sweat glands can be found in humans: eccrine glands and apocrine glands. The eccrine sweat glands are distr ...

hyperthermia Hyperthermia, also known simply as overheating, is a condition in which an individual's body temperature is elevated beyond normal due to failed thermoregulation. The person's body produces or absorbs more heat than it dissipates. When extreme ...

, tremors, gastrointestinal complications (

diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin wi ...

abdominal pain Abdominal pain, also known as a stomach ache, is a symptom Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than ...

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the ...

vomiting Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the Human nose, nose. Vomiting can be the result of ailments like Food-poisoning, foo ...

) and

pancreatitis Pancreatitis is a condition characterized by inflammation of the pancreas. The pancreas is a large organ behind the stomach that produces digestive enzymes and a number of hormones. There are two main types: acute pancreatitis, and chronic pancr ...

Convulsions A convulsion is a medical condition where the body muscles contract and relax rapidly and repeatedly, resulting in uncontrolled shaking. Because epileptic seizures typically include convulsions, the term ''convulsion'' is sometimes used as a s ...

and

coma A coma is a deep state of prolonged unconsciousness in which a person cannot be awakened, fails to respond normally to painful stimuli, light, or sound, lacks a normal wake-sleep cycle and does not initiate voluntary actions. Coma patients exhi ...

are relatively rare, but can occur. Death usually results from

pulmonary edema Pulmonary edema, also known as pulmonary congestion, is excessive edema, liquid accumulation in the parenchyma, tissue and pulmonary alveolus, air spaces (usually alveoli) of the lungs. It leads to impaired gas exchange and may cause hypoxemia an ...

and

cardiorespiratory failure Respiratory arrest is a sickness caused by apnea (cessation of breathing) or respiratory dysfunction severe enough it will not sustain the body (such as agonal breathing). Prolonged apnea refers to a patient who has stopped breathing for a long per ...

. Deaths can occur between 1–6 hours, or 12–14 hours, depending on the age group, the person's state of health and the quantity of injected venom. The venom of this species seems to have different lethalities according to its distribution, ''T. serrulatus'' from

has an

LD50 In toxicology, the median lethal dose, LD50 (abbreviation for "lethal dose, 50%"), LC50 (lethal concentration, 50%) or LCt50 is a toxic unit that measures the lethal dose of a toxin, radiation, or pathogen. The value of LD50 for a substance is the ...

of 51.6 μg / kg, compared to LD50 from ''T. serrulatus'' from

: 26 μg / kg. According to a nationwide epidemiological study of scorpion accidents that was conducted from 2000 to 2012, there were 482,616 accidents and 728 deaths reported in Brazil during that period. All of the fatal cases were attributed to the genus ''Tityus'', and ''T. serrulatus'', in particular, was believed to be responsible for the vast majority of scorpion-related deaths considered by the study.

References

{{Taxonbar, from=Q1937851 serrulatus Fauna of Brazil Animals described in 1922 Scorpions of South America