Michoacan dwarf spiny-tailed iguana  (Ctenosaura clarki)

The Michoacan dwarf spiny-tailed iguana is classified as Vulnerable (VU) on the IUCN Red List (1).

Also known as the Balsas armed lizard, the Michoacan dwarf spiny-tailed iguana (Ctenosaura clarki) is a small brown and tan coloured lizard. It belongs to a group of poorly understood iguanas, the Ctenosaura, that all share a characteristic spiny tail (2).

The most distinguishing feature of the Michoacan dwarf spiny-tailed iguana is its large and muscular tail, which is covered with sharp, spiny scales. The tail is used to slap prey or an opponent in an attempt to inflict an injury, sometimes resulting in impressive wounds (3).

The Michoacan dwarf spiny-tailed iguana is found only in the Mexican state of Michoacán, from which it takes its name. Within Michoacán, it occurs in the Tepalcatepec Valley and at the Michoacán - Guerrero border (4).

The Michoacan dwarf spiny-tailed iguanainhabits dry, hot, cactus-covered rocky hillsides (5).

A semi-arboreal species (1), the Michoacan dwarf spiny-tailed iguana generally rests during the night in a hollow cavity in tree cacti. The iguana will block the entrance to the cavity by arching its large, muscular spiny tail. As the iguana grows, it will take shelter in larger cavities (1) (3).

In general, most species of spiny-tailed iguanas will venture out from their retreats during the day, when the outside temperature reaches a comfortable level. The iguanas then bask in a sunny area until their optimum body temperature is reached. Reptiles are unable to maintain their own body temperature and therefore rely on sources of heat from the environment, such as the sun, to increase the temperature of the body and provide them with enough energy to sustain their daily activities (6).

Throughout the day, spiny-tailed iguana species will usually forage, bask, rest and display, before returning to their retreats as the sun starts to set. Displays typically involve a male spiny-tailed iguana patrolling its territory by standing high on its legs, flattening its body, and bobbing its head with its mouth open to intimidate other males (2).

Reproduction in spiny-tailed iguanas begins with the male chasing the female. Following capture, the male uses its front legs to pin down the female, and uses its mouth to hold the female by the back of the neck while attempting to copulate. Eight to ten weeks after mating, the female digs a nest in the ground in which to lay the eggs. The eggs take around 90 days to hatch, depending on the temperature. Upon hatching, the young iguanas immediately dig their way out of the underground nest (2).

The primary threat to the Michoacan dwarf spiny-tailed iguana is the loss of its habitat (1), but it is also threatened by collection for the international pet trade (1).

The Michoacan dwarf spiny-tailed iguana is protected by law in Mexico (1), but there are not known to be any other conservation measures in place for this threatened species.

It has been recommended that more research is carried out into the biology and habitat of this species (1), which will help inform any future conservation measure that are implemented.

Learn more about the conservation of iguanas and other reptiles:

• Reptile and Amphibian Ecology International:
  http://www.reptilesandamphibians.org/
• International Reptile Conservation:
  http://www.ircf.org/

Find out about conservation in Mexico:

• The Nature Conservancy:
  http://www.nature.org/ourinitiatives/regions/northamerica/mexico