The Rio Fuerte beaded lizard (''Heloderma exasperatum'') is a

venom Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...

ous

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of beaded lizard in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Helodermatidae The Helodermatidae or beaded lizards are a small family of lizards endemic to North America today, mainly found in the Isthmus of Tehuantepec in Oaxaca, the central lowlands of Chiapas, on the border of Guatemala, and in the Nentón River Valley, ...

. It is found in the tropical forests and shrublands of western

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

, specifically around the Rio Fuerte and Rio Mayo basins. It is often found in or near abandoned mammal burrows and sources of water.

Geographic range

''H. exasperatum'' is found in southwestern Chihuahua and southern

Sonora Sonora (), officially Estado Libre y Soberano de Sonora (), is one of the 31 states which, along with Mexico City, comprise the Administrative divisions of Mexico, Federal Entities of Mexico. The state is divided into Municipalities of Sonora, 72 ...

, Mexico, up to an altitude of .

Description

As an adult, the Rio Fuerte beaded lizard ranges from 60 to 90 cm (23.6 to 35.4 in) in total length (including tail). It can weigh up to 4 kg (8.8 lb). It is very similar to the Mexican beaded lizard in appearance and size.

Diet

''H. exasperatum'' feeds mainly on reptile eggs, but also eats bird eggs, and nestlings of birds and mammals.

Reproduction

''H. exasperatum'' is

oviparous Oviparous animals are animals that reproduce by depositing fertilized zygotes outside the body (i.e., by laying or spawning) in metabolically independent incubation organs known as eggs, which nurture the embryo into moving offsprings kno ...

Taxonomy

The Rio Fuerte beaded lizard is a member of the family

. The species was formerly considered a subspecies of the Mexican beaded lizard, which is its closest living relative, but was elevated to full species status in 2013. (''Heloderma exasperatum'', new taxonomic status).

Etymology

The generic name, ''Heloderma'', means "studded skin", from the Ancient Greek words hêlos (ηλος), meaning "the head of a nail or stud", and derma (δερμα), meaning "skin". The specific name, ''exasperatum'', means "completely rough" in Latin.