Cyclura nubila caymanensis

The Lesser Caymans Iguana or Cayman Brac Iguana or Cayman Island Brown Iguana or Sister Isles Iguana (Cyclura nubila caymanensis) is a critically endangered subspecies of the Cuban Iguana (Cyclura nubila). It is native to two islands to the south of Cuba: Cayman Brac and Little Cayman, which are also known as the Sister Isles due to their similar shapes and close proximity to each other. This subspecies is in decline due to habitat encroachment by human development and predation by feral dogs and cats. It is nearly extinct on Cayman Brac (less than 50 animals) and Little Cayman supports a population of 1,500 animals.

Taxonomy

The Lesser Caymans Iguana, Cyclura nubila caymanensis, is endemic to the islands of Little Cayman and Cayman Brac. It is a subspecies of the Cuban Iguana. This subspecies has been introduced to Grand Cayman, where it has interbred with that island's native Blue Iguana, (Cyclura Lewisi).^[1]^[2]

The generic name (Cyclura) is derived from the Ancient Greek cyclos (??????) meaning "circular" and ourá (????) meaning "tail", after the thick-ringed tail characteristic of all Cyclura.^[3] Its specific name, nubila, is Latin for "gray" but in this instance is a Latinized form of the name of John Edward Gray, the British zoologist who first described the Cuban Rock Iguana as a species in 1831 as opposed to the animal's base color.^[4]^[5] Its subspecific name Caymanensis refers to the island where it lives being a Latinized form of "Cayman".

Zoologists Thomas Barbour and Gladwyn Kingsley Noble first described the Lesser Caymans Iguana as a species in 1916.^[4]^[5] Chapman Grant, in a monograph published in 1940, formally described the Lesser Caymans Iguana for the first time as a subspecies: Cyclura macleayi caymanensis.^[4]^[1]^[5]

In 1975 Albert Schwartz and Thomas established the trinomial nomenclature, Cyclura nubila caymanensis for the Lesser Cayman Iguana.^[1]^[5] They maintained that this lizard was a subspecies of Cyclura nubila nubila commonly known as the Cuban Rock Iguana(the species from which it evolved and can breed with if placed together under artificial conditions).^[4]^[1]

Anatomy and morphology

The Lesser Caymans Iguana, Cyclura nubila caymanensis, is a large species of Cyclura with a body length of 20 to 30 inches and an equally long tail.^[6] Males are significantly larger than females.^[7] The Lesser Caymans Iguana has a skin color from light grey to green when mature, with a light blue or reddish-pink colored head, whereas females are more olive green, lacking any red or blue.^[7] Young animals tend to be uniformly dark brown or green with faint dark bands.^[7] Their distinctive black feet stand in contrast to the rest of their lighter overall body color.^[7] Their eye-color is typically brown to blood red. An individual of this subspecies has been recorded as one of the longest lived of all species and subspecies of the genus Cyclura at 33 years.^[8]

Like other Cyclura species, male Lesser Caymans Iguanas have femoral pores on their thighs, which are used to release pheromones.^[7] As females lack these pores and are smaller in body size compared to males, the animals are somewhat sexually dimorphic.^[7]^[9]

Distribution and habitat

Like other members of the Genus Cyclura the Lesser Caymans Iguana requires suitable areas in which to bask, forage, nest, and hide.^[4] On Little Cayman these requirements are met in a variety of interior habitats even though the iguanas are widely dispersed.^[4]^[10]

Diet

Like all Cyclura species the Lesser Caymans Iguana is primarily herbivorous, consuming leaves, flowers and fruits from over 100 different plant species.^[4]^[6] This diet is very rarely, if ever supplemented with animal matter.^[4]^[6]

Mating

Mating occurs in April to May depending when the dry season ends, and 7-25 eggs are usually laid in May or June depending on the size and age of the female.^[4] Due to being forced to dwell inland where the soil is rocky, the females often have to migrate to coastal areas in order to build their nests in the sand.^[4]^[11] The hatchlings emerge from the nests in August to early September.^[4]

Conservation

Endangered status

The Lesser Caymans Iguana is critically endangered according to the current IUCN Red List.^[4] The subspecies is vital to its native ecosystem as a seed disperser for native vegetation, and its extinction could have serious consequences as many of Little Cayman's and Cayman Brac's plants are not found elsewhere.^[12]

Causes of decline

Habitat destruction is the main factor threatening the future of this iguana.^[4]^[10] The iguanas nest in the sand of beaches that are a prime real-estate location on Little Cayman.^[7]^[10]

Predation and injury to hatchlings by rats, to hatchlings and sub-adults by semi-domestic and feral cats, and killing of adults by roaming dogs are all placing severe pressure on the remaining wild population on both islands.^[4]

Recovery efforts

A formal captive breeding program does not exist for this subspecies but it may be warranted for the Cayman Brac population.^[13] As the population on Cayman Brac has not been found to be genetically distinct from the Little Cayman population; genetic diversity may be introduced from the Little Cayman population if it is needed.^[13]

Captivity

The Lesser Caymans Iguana is established in captivity, both in public and private collections.^[6] Private individuals have established these animals in captive breeding programs (both purebred and occasionally mixed with either the Blue Iguana, Cuban Iguana, and sometimes with both) minimizing the demand for wild-caught specimens for the pet trade.^[6]

References