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 In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of beaded lizard in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Helodermatidae The Helodermatidae or beaded lizards are a small family of lizards endemic to North America today, but formerly more widespread in the ancient past. Traditionally, the Gila monster and the Mexican beaded lizard were the only species recognized, ...

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

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

, specifically around the

Rio Fuerte The Fuerte River is a river in the state of Sinaloa, in northwestern Mexico. It flows from headwaters in the Sierra Madre Occidental to the Pacific Ocean in the Gulf of California. Course It begins at the junction of the Rio Verde (also called ...

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 ( en, Free and Sovereign State of 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 d ...

, 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 The Mexican beaded lizard (''Heloderma horridum'') is a species of lizard in the family Helodermatidae, one of the two species of venomous beaded lizards found principally in Mexico and southern Guatemala. It and the other member of the same gen ...

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 lay their eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, most reptiles, and all pterosaurs, dinosaurs (including birds), and ...

Taxonomy

The Rio Fuerte beaded lizard is a member of the family

. The species was formerly considered a subspecies of the

, 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.