Beaded lizard
Encyclopedia
The Beaded lizard is a species of venomous lizard
found principally in Mexico
and southern Guatemala
. Along with its congener
, the Gila monster
(Heloderma suspectum), it is the only lizard to have evolved an overt venom delivery system, and has long been considered the only venomous lizard. The beaded lizard is larger than the Gila monster but has duller coloration, black with yellowish bands of differing width depending on the subspecies. A specialized predator that feeds primarily upon eggs, the primary use of its venom is still a source of debate among scientists. However, this venom has been found to contain several enzyme
s useful for manufacturing drugs in the treatment of diabetes, and research on the pharmacological use of its venom is ongoing.
Threatened throughout its range by overcollection and habitat loss
, it is a CITES protected animal. The Motagua Valley subspecies
(H. h. charlesborgeti) is one of the rarest lizards in the world, with a wild population of fewer than 200 animals.
period. The genus Heloderma has existed since the Miocene
, when H. texana ranged over most of North America. Because the Helodermatids have remained relatively unchanged morphologically, they are occasionally regarded as living fossil
s. Although the beaded lizard appears closely related to the monitor lizard
s (varanids) of Africa, Asia and Australia, the wide geographical separation and unique features not found in the varanids indicates that the beaded lizard is better placed in a separate family.
The species was first described in 1829 by Arend Wiegmann
as Trachyderma horridum, however, he renamed it Heloderma horridum six months later. Its generic
name Heloderma means "studded skin", from the Ancient Greek
words hêlos (ηλος)—the head of a nail or stud—and derma (δερμα), meaning skin. Its specific
name, Horrĭdum, is the Latin
word meaning rough or rude.
There are four subspecies
of beaded lizard:
Adult beaded lizards range from 24 inches (61 cm) to 36 inches (91.4 cm) in length. It is substantially larger than the Gila monster, which only reaches lengths of 12 inches (30.5 cm) to 16 inches (40.6 cm). Although males are slightly larger than females, the animals are not sexually dimorphic. Both males and females are stocky with broad heads, although the males tend to be broader. The beaded lizard's scales
are small, bead-like and non-overlapping. Except for the underside of the animal, the majority of its scales are underlaid with bony osteoderms.
Their base color is black and marked with varying amounts of yellow spots or bands, with the exception of H. h. alvarezi, which tends to be all black in color. The beaded lizard has a short tail which is used to store fat so the animal can survive during months of estivation
. Unlike many other lizards, this tail does not autotomize
and cannot grow back if broken. The beaded lizard has a forked black tongue which it uses to smell, with the help of a Jacobson's organ; it sticks its tongue out to gather scents and touches it to the opening of the organ when the tongue is retracted.
to Southwestern Guatemala
and two Atlantic drainages, from Central Chiapas
to Southeastern Guatemala. Their habitat is primarily tropical deciduous forest and thorn scrub
forest, but are found in pine-oak forest, with elevations from sea level
to 1500 meters. In the wild, the animals are only active from April to mid-November, spending about an hour per day above the ground.
The nominate subspecies H. h. horridum is found in Mexico, from Sonora
to Oaxaca
. The Rio Fuerte beaded lizard (H. h. exasperatum) is found from southern Sonora to northern Sinaloa
. The Black beaded lizard ( H. h. alvarezi) is found in the northern Chiapas
and the depression of the Río Lagartero in Huehuetenango
to northwestern Guatemala. The ranges of these three subspecies overlap, making them sympatric. The Motagua Valley subspecies (H. h. charlesbogerti) is the only allopatric one, separated from the nearest population (H. h. alvarezi) by 250 km of unsuitable habitat. The Motagua Valley beaded lizard is the most endangered of the subspecies if not of all lizards; it is found only in the dry valley
of the Río Motagua in the north-east of Guatemala; it is believed less than 200 of these animals exist in the wild.
nest predator feeding primarily on bird and reptile eggs
. A semi-arboreal species, it is found climbing deciduous
trees in search of prey when encountered above ground. It will occasionally prey upon small birds, mammals, frogs, lizards, and insects. Steve Angeli and Robert Applegate, noted captive breeders of the beaded lizard, have remarked that captive specimens, both wild-caught and captive-born will often refuse any food, except for eggs.
.jpg)
glands of the beaded lizard are modified salivary gland
s located in the animal's lower jaw. Each gland has a separate duct leading to the base of its grooved teeth. When biting, the beaded lizard hangs on its victim and chews in order to get its venomous saliva into the wound. Although its jaw grip is strong its unsocketed teeth are easily broken off at their bases. The beaded lizard's venom is a weak hemotoxin
and although human deaths are rare, it can cause respiratory failure
. It consists of a number of components, including L-amino acid oxidase, hyaluronidase, phospholipase A, serotonin, and highly active kallikrein
s that release vasoactive kinins. The venom contains no enzymes that significantly affect coagulation. Almost all documented bites (eight in the past 100 years) have resulted from prodding captive animals with a finger or bare foot.
While invertebrates are essentially immune to the effects of this venom, effects on vertebrates are more severe and varied. In mammals such as rats, major effects include a rapid reduction in carotid blood flow followed by a marked fall in blood pressure, respiratory irregularities, tachycardia and other cardiac anomalies, as well as hypothermia
, edema
, and internal hemorrhage in the gastrointestinal tract
, lungs, eyes, liver, and kidneys. In humans, the effects of bites are associated with excruciating pain that may extend well beyond the area bitten and persist up to 24 hours. Other common effects of bites on humans include local edema (swelling), weakness, sweating, and a rapid fall in blood pressure. Beaded lizards are immune to the effects of their own venom.
The compounds which have been studied in its saliva have pharmacological properties relating to diabetes, Alzheimer’s disease and even HIV
. This hormone was named exendin-3 and is marketed by Amylin Pharmaceuticals
as the drug:Exenatide
. One study done in 1996 revealed that it binds to cell receptors from breast cancer cells and may stop the growth of lung cancer cells.
that often lasts several hours; the victor mates
with the female. The female lays her clutch of 2 to 30 eggs
between October and December, the clutch hatching the following June or July.
Young lizards are seldom seen. It is believed they spend much of their early life underground, emerging at two to three years of age after gaining considerable size.
The beaded lizard is surrounded by myth and superstition in much of its native range
. It is incorrectly believed, for example, that the lizard is more venomous than a rattlesnake
, that it can cause lightning strikes
with its tail, or make a pregnant woman miscarry by merely looking at it. As a result of this superstition, locals often kill the lizard on sight.
The seldom seen lizard is poached
for resale through the illegal exotic animal trade. It does not reproduce well in captivity, and its scarcity means a high price for collectors. As a direct result, the beaded lizard is protected by Mexican law under the category A (Threatened), and it dwells within the range of several protected areas. In Guatemala it is protected by national legislation, and part of their range is within protected areas. It is listed on Appendix II of CITES.
Fewer than 200 individual animals remain in the dry forest
habitat of the Motagua Valley
and this subspecies of beaded lizard (Heloderma horridum charlesbogerti
) was facing extinction due to local extermination and loss of habitat for agricultural purposes. A conservation effort has been launched known as Project Heloderma in order to preserve the semi-arid
habitat of the Motagua Valley by The Nature Conservancy
and partners such as ZOOTROPIC, CONAP, the IRCF (International Reptile Conservation Foundation), Zoo Atlanta
, and the San Diego Zoo
. This effort has been successful in getting the Guatemalan government to list the beaded lizard under the Convention on International Trade in Endangered Species (CITES) as an Appendix I animal, making it illegal to export the species.
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
found principally in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
and southern Guatemala
Guatemala
Guatemala is a country in Central America bordered by Mexico to the north and west, the Pacific Ocean to the southwest, Belize to the northeast, the Caribbean to the east, and Honduras and El Salvador to the southeast...
. Along with its congener
Congener
Congener has several different meanings depending on the field in which it is used. Colloquially, it is used to mean a person or thing like another, in character or action.-Biology:In biology, congeners are organisms within the same genus...
, the Gila monster
Gila monster
The Gila monster is a species of venomous lizard native to the southwestern United States and northwestern Mexican state of Sonora...
(Heloderma suspectum), it is the only lizard to have evolved an overt venom delivery system, and has long been considered the only venomous lizard. The beaded lizard is larger than the Gila monster but has duller coloration, black with yellowish bands of differing width depending on the subspecies. A specialized predator that feeds primarily upon eggs, the primary use of its venom is still a source of debate among scientists. However, this venom has been found to contain several enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
s useful for manufacturing drugs in the treatment of diabetes, and research on the pharmacological use of its venom is ongoing.
Threatened throughout its range by overcollection and habitat loss
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...
, it is a CITES protected animal. The Motagua Valley subspecies
Heloderma horridum charlesbogerti
The Motagua Valley beaded lizard, Heloderma horridum charlesbogerti, is a highly endangered subspecies of beaded lizard, a venomous lizard endemic to the dry forests of the Motagua Valley in southeastern Guatemala. It is the only allopatric subspecies, separated from the nearest population of...
(H. h. charlesborgeti) is one of the rarest lizards in the world, with a wild population of fewer than 200 animals.
Taxonomy
The beaded lizard has one close living relative, the Gila monster (H. suspectum), as well as many extinct relatives in the Helodermatidae whose evolutionary history may be traced back to the CretaceousCretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
period. The genus Heloderma has existed since the Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
, when H. texana ranged over most of North America. Because the Helodermatids have remained relatively unchanged morphologically, they are occasionally regarded as living fossil
Living fossil
Living fossil is an informal term for any living species which appears similar to a species otherwise only known from fossils and which has no close living relatives, or a group of organisms which have long fossil records...
s. Although the beaded lizard appears closely related to the monitor lizard
Monitor lizard
Monitor lizards are usually large reptiles, although some can be as small as in length. They have long necks, powerful tails and claws, and well-developed limbs. Most species are terrestrial, but arboreal and semiaquatic monitors are also known...
s (varanids) of Africa, Asia and Australia, the wide geographical separation and unique features not found in the varanids indicates that the beaded lizard is better placed in a separate family.
The species was first described in 1829 by Arend Wiegmann
Arend Friedrich August Wiegmann
Arend Friedrich August Wiegmann was a German zoologist. He studied medicine and philology at the University of Leipzig, and afterwards was an assistant to Martin Lichtenstein in Berlin...
as Trachyderma horridum, however, he renamed it Heloderma horridum six months later. Its generic
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
name Heloderma means "studded skin", from the Ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
words hêlos (ηλος)—the head of a nail or stud—and derma (δερμα), meaning skin. Its specific
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
name, Horrĭdum, is the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
word meaning rough or rude.
There are four subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
of beaded lizard:
- Mexican beaded lizard (Heloderma horridum horridum) (Wiegmann, 1829)
- Black beaded lizard (H. h. alvarezi) BogertCharles Mitchill BogertCharles Mitchill Bogert was an American herpetologist, and curator of herpetology and researcher for the American Museum of Natural History.-Early life and education:...
and Martin del Campo, 1956 - Rio Fuerte beaded lizard (H. h. xasperatum) BogertCharles Mitchill BogertCharles Mitchill Bogert was an American herpetologist, and curator of herpetology and researcher for the American Museum of Natural History.-Early life and education:...
and Martin del Campo, 1956 - Motagua Valley beaded lizard (Heloderma horridum charlesbogertiHeloderma horridum charlesbogertiThe Motagua Valley beaded lizard, Heloderma horridum charlesbogerti, is a highly endangered subspecies of beaded lizard, a venomous lizard endemic to the dry forests of the Motagua Valley in southeastern Guatemala. It is the only allopatric subspecies, separated from the nearest population of...
) Campbell and Vannini, 1988
Description
Scale (zoology)
In most biological nomenclature, a scale is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran species, scales are plates on the surface of the insect wing, and provide coloration...
are small, bead-like and non-overlapping. Except for the underside of the animal, the majority of its scales are underlaid with bony osteoderms.
Their base color is black and marked with varying amounts of yellow spots or bands, with the exception of H. h. alvarezi, which tends to be all black in color. The beaded lizard has a short tail which is used to store fat so the animal can survive during months of estivation
Estivation
Aestivation is a state of animal dormancy, characterized by inactivity and a lowered metabolic rate, that is entered in response to high temperatures and arid conditions...
. Unlike many other lizards, this tail does not autotomize
Autotomy
Autotomy or self amputation is the act whereby an animal severs one or more of its own appendages, usually as a self-defense mechanism designed to elude a predator's grasp...
and cannot grow back if broken. The beaded lizard has a forked black tongue which it uses to smell, with the help of a Jacobson's organ; it sticks its tongue out to gather scents and touches it to the opening of the organ when the tongue is retracted.
Habitat and range
The beaded lizard is found in the Pacific drainages from Southern SonoraSonora
Sonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....
to Southwestern Guatemala
Guatemala
Guatemala is a country in Central America bordered by Mexico to the north and west, the Pacific Ocean to the southwest, Belize to the northeast, the Caribbean to the east, and Honduras and El Salvador to the southeast...
and two Atlantic drainages, from Central Chiapas
Chiapas
Chiapas officially Estado Libre y Soberano de Chiapas is one of the 31 states that, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 118 municipalities and its capital city is Tuxtla Gutierrez. Other important cites in Chiapas include San Cristóbal de las...
to Southeastern Guatemala. Their habitat is primarily tropical deciduous forest and thorn scrub
Deserts and xeric shrublands
Deserts and xeric shrublands is a biome characterized by, relating to, or requiring only a small amount of moisture.-Definition and occurrence:...
forest, but are found in pine-oak forest, with elevations from sea level
Sea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...
to 1500 meters. In the wild, the animals are only active from April to mid-November, spending about an hour per day above the ground.
The nominate subspecies H. h. horridum is found in Mexico, from Sonora
Sonora
Sonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....
to Oaxaca
Oaxaca
Oaxaca , , officially Estado Libre y Soberano de Oaxaca is one of the 31 states which, along with the Federal District, comprise the 32 federative entities of Mexico. It is divided into 571 municipalities; of which 418 are governed by the system of customs and traditions...
. The Rio Fuerte beaded lizard (H. h. exasperatum) is found from southern Sonora to northern Sinaloa
Sinaloa
Sinaloa officially Estado Libre y Soberano de Sinaloa is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 18 municipalities and its capital city is Culiacán Rosales....
. The Black beaded lizard ( H. h. alvarezi) is found in the northern Chiapas
Chiapas
Chiapas officially Estado Libre y Soberano de Chiapas is one of the 31 states that, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 118 municipalities and its capital city is Tuxtla Gutierrez. Other important cites in Chiapas include San Cristóbal de las...
and the depression of the Río Lagartero in Huehuetenango
Huehuetenango
Huehuetenango is a city and a municipality in the highlands of western Guatemala. It is also the capital of the department of Huehuetenango. The municipality's population was over 81,000 people in 2002...
to northwestern Guatemala. The ranges of these three subspecies overlap, making them sympatric. The Motagua Valley subspecies (H. h. charlesbogerti) is the only allopatric one, separated from the nearest population (H. h. alvarezi) by 250 km of unsuitable habitat. The Motagua Valley beaded lizard is the most endangered of the subspecies if not of all lizards; it is found only in the dry valley
Dry valley
A dry valley is a valley found in either karst or chalk terrain that no longer has a surface flow of water.There are many examples of the latter along the North and South Downs in southern England...
of the Río Motagua in the north-east of Guatemala; it is believed less than 200 of these animals exist in the wild.
Diet
The beaded lizard is a specialized vertebrateVertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...
nest predator feeding primarily on bird and reptile eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
. A semi-arboreal species, it is found climbing deciduous
Deciduous
Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...
trees in search of prey when encountered above ground. It will occasionally prey upon small birds, mammals, frogs, lizards, and insects. Steve Angeli and Robert Applegate, noted captive breeders of the beaded lizard, have remarked that captive specimens, both wild-caught and captive-born will often refuse any food, except for eggs.
Venom
The venomVenom
Venom is the general term referring to any variety of toxins used by certain types of animals that inject it into their victims by the means of a bite or a sting...
glands of the beaded lizard are modified salivary gland
Salivary gland
The salivary glands in mammals are exocrine glands, glands with ducts, that produce saliva. They also secrete amylase, an enzyme that breaks down starch into maltose...
s located in the animal's lower jaw. Each gland has a separate duct leading to the base of its grooved teeth. When biting, the beaded lizard hangs on its victim and chews in order to get its venomous saliva into the wound. Although its jaw grip is strong its unsocketed teeth are easily broken off at their bases. The beaded lizard's venom is a weak hemotoxin
Hemotoxin
Hemotoxins, haemotoxins or hematotoxins are toxins that destroy red blood cells , disrupt blood clotting, and/or cause organ degeneration and generalized tissue damage. The term hemotoxin is to some degree a misnomer since toxins that damage the blood also damage other tissues...
and although human deaths are rare, it can cause respiratory failure
Respiratory failure
The term respiratory failure, in medicine, is used to describe inadequate gas exchange by the respiratory system, with the result that arterial oxygen and/or carbon dioxide levels cannot be maintained within their normal ranges. A drop in blood oxygenation is known as hypoxemia; a rise in arterial...
. It consists of a number of components, including L-amino acid oxidase, hyaluronidase, phospholipase A, serotonin, and highly active kallikrein
Kallikrein
Kallikreins are a subgroup of serine proteases, enzymes capable of cleaving peptide bonds in proteins. In humans, plasma kallikrein has no known homologue, while tissue kallikrein-related peptidases encode a family of fifteen closely related serine proteases...
s that release vasoactive kinins. The venom contains no enzymes that significantly affect coagulation. Almost all documented bites (eight in the past 100 years) have resulted from prodding captive animals with a finger or bare foot.
While invertebrates are essentially immune to the effects of this venom, effects on vertebrates are more severe and varied. In mammals such as rats, major effects include a rapid reduction in carotid blood flow followed by a marked fall in blood pressure, respiratory irregularities, tachycardia and other cardiac anomalies, as well as hypothermia
Hypothermia
Hypothermia is a condition in which core temperature drops below the required temperature for normal metabolism and body functions which is defined as . Body temperature is usually maintained near a constant level of through biologic homeostasis or thermoregulation...
, edema
Edema
Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...
, and internal hemorrhage in the gastrointestinal tract
Gastrointestinal tract
The human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....
, lungs, eyes, liver, and kidneys. In humans, the effects of bites are associated with excruciating pain that may extend well beyond the area bitten and persist up to 24 hours. Other common effects of bites on humans include local edema (swelling), weakness, sweating, and a rapid fall in blood pressure. Beaded lizards are immune to the effects of their own venom.
HIV
Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...
. This hormone was named exendin-3 and is marketed by Amylin Pharmaceuticals
Amylin Pharmaceuticals
Amylin Pharmaceuticals is a biopharmaceutical company based in San Diego, CA, that was founded in 1987. The company is engaged in the discovery, development and commercialization of drug candidates for the treatment of diabetes, obesity and other diseases. Currently, Amylin produces two drugs,...
as the drug:Exenatide
Exenatide
Exenatide is a medication approved in April 2005 for the treatment of diabetes mellitus type 2. It belongs to the group of incretin mimetics and is manufactured by Amylin Pharmaceuticals and Eli Lilly and Company....
. One study done in 1996 revealed that it binds to cell receptors from breast cancer cells and may stop the growth of lung cancer cells.
Reproduction
The beaded lizard becomes sexually mature at six to eight years of age and mates between September and October. Males engage in ritual combatAgonistic behaviour
In ethology, agonistic behaviour is any social behaviour related to fighting. Thus it is broader than aggressive behaviour because it includes not only actual aggression but also threats, displays, retreats, placating aggressors, and conciliation. The term was coined by Scott and Fredericson in 1951...
that often lasts several hours; the victor mates
Mating
In biology, mating is the pairing of opposite-sex or hermaphroditic organisms for copulation. In social animals, it also includes the raising of their offspring. Copulation is the union of the sex organs of two sexually reproducing animals for insemination and subsequent internal fertilization...
with the female. The female lays her clutch of 2 to 30 eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
between October and December, the clutch hatching the following June or July.
Young lizards are seldom seen. It is believed they spend much of their early life underground, emerging at two to three years of age after gaining considerable size.
Conservation
Range (biology)
In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.The term is often qualified:...
. It is incorrectly believed, for example, that the lizard is more venomous than a rattlesnake
Rattlesnake
Rattlesnakes are a group of venomous snakes of the genera Crotalus and Sistrurus of the subfamily Crotalinae . There are 32 known species of rattlesnake, with between 65-70 subspecies, all native to the Americas, ranging from southern Alberta and southern British Columbia in Canada to Central...
, that it can cause lightning strikes
Lightning
Lightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...
with its tail, or make a pregnant woman miscarry by merely looking at it. As a result of this superstition, locals often kill the lizard on sight.
The seldom seen lizard is poached
Poaching
Poaching is the illegal taking of wild plants or animals contrary to local and international conservation and wildlife management laws. Violations of hunting laws and regulations are normally punishable by law and, collectively, such violations are known as poaching.It may be illegal and in...
for resale through the illegal exotic animal trade. It does not reproduce well in captivity, and its scarcity means a high price for collectors. As a direct result, the beaded lizard is protected by Mexican law under the category A (Threatened), and it dwells within the range of several protected areas. In Guatemala it is protected by national legislation, and part of their range is within protected areas. It is listed on Appendix II of CITES.
Fewer than 200 individual animals remain in the dry forest
Tropical and subtropical dry broadleaf forests
The tropical and subtropical dry broadleaf forest biome, also known as tropical dry forest, is located at tropical and subtropical latitudes. Though these forests occur in climates that are warm year-round, and may receive several hundred centimeters of rain per year, they have long dry seasons...
habitat of the Motagua Valley
Motagua River
The Motagua River is a long river in Guatemala. It rises in the western highlands of Guatemala where it is also called Río Grande, and runs in an easterly direction to the Gulf of Honduras. The final few kilometres of the river form part of the Guatemala/Honduras border...
and this subspecies of beaded lizard (Heloderma horridum charlesbogerti
Heloderma horridum charlesbogerti
The Motagua Valley beaded lizard, Heloderma horridum charlesbogerti, is a highly endangered subspecies of beaded lizard, a venomous lizard endemic to the dry forests of the Motagua Valley in southeastern Guatemala. It is the only allopatric subspecies, separated from the nearest population of...
) was facing extinction due to local extermination and loss of habitat for agricultural purposes. A conservation effort has been launched known as Project Heloderma in order to preserve the semi-arid
Semi-arid
A semi-arid climate or steppe climate describes climatic regions that receive precipitation below potential evapotranspiration, but not extremely...
habitat of the Motagua Valley by The Nature Conservancy
The Nature Conservancy
The Nature Conservancy is a US charitable environmental organization that works to preserve the plants, animals, and natural communities that represent the diversity of life on Earth by protecting the lands and waters they need to survive....
and partners such as ZOOTROPIC, CONAP, the IRCF (International Reptile Conservation Foundation), Zoo Atlanta
Zoo Atlanta
Zoo Atlanta is an Association of Zoos and Aquariums accredited zoological park in Atlanta, Georgia. Founded in 1889, the Zoo is Atlanta’s oldest cultural destination and is one of the oldest continuously operating zoological institutions in the United States.Zoo Atlanta houses over 1,300 animals...
, and the San Diego Zoo
San Diego Zoo
The San Diego Zoo in Balboa Park, San Diego, California, is one of the most progressive zoos in the world, with over 4,000 animals of more than 800 species...
. This effort has been successful in getting the Guatemalan government to list the beaded lizard under the Convention on International Trade in Endangered Species (CITES) as an Appendix I animal, making it illegal to export the species.