The Sombrero ameiva (''Pholidoscelis corvinus'') is a

lizard Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia alt ...

species in the genus ''

Ameiva ''Ameiva'', commonly called jungle-runners, is a genus of whiptail lizards that belongs to the family Teiidae. Geographic range Member species of the genus ''Ameiva'' are found in South America, Central America and the Caribbean (West Indies) ...

''. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

Sombrero A sombrero (Spanish , ) is a type of wide-brimmed Mexican men's hat used to shield the face and eyes from the sun. It usually has a high pointed crown, an extra-wide brim (broad enough to cast a shadow over the head, neck and shoulders of the we ...

, a small, uninhabited island in the

Lesser Antilles The Lesser Antilles ( es, link=no, Antillas Menores; french: link=no, Petites Antilles; pap, Antias Menor; nl, Kleine Antillen) are a group of islands in the Caribbean Sea. Most of them are part of a long, partially volcanic island arc betwe ...

under the jurisdiction of

Anguilla Anguilla ( ) is a British Overseas Territory in the Caribbean. It is one of the most northerly of the Leeward Islands in the Lesser Antilles, lying east of Puerto Rico and the Virgin Islands and directly north of Saint Martin. The territo ...

Description

Adults are

melanistic The term melanism refers to black pigment and is derived from the gr, μελανός. Melanism is the increased development of the dark-colored pigment melanin in the skin or hair. Pseudomelanism, also called abundism, is another variant of pi ...

, appearing plain brown to slate black, with a dark green to black ventral surface mottled with light blue. Its tail is sometimes spotted green. Males have brown flecks on the dorsal surface and browner heads. Males grow to 133 mm snout-to-vent length, with females being considerably smaller. It is superficially similar in coloration and scalation to ''

Pholidoscelis atratus The Redonda ameiva (''Pholidoscelis atratus'') is a species of lizard found only on Redonda. It is sometimes described as a subspecies In biological classification, subspecies is a rank below species, used for populations that live in diff ...

'' and '' Pholidoscelis corax'', two other melanistic species also found on small, barren islands in the Caribbean. As both

island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island ...

s have similar

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s, this is likely the result of independent adaptation. Its diet includes the

eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...

of ground-nesting

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

Conservation

The Sombrero ameiva is listed as critically endangered on the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...

due to its limited distribution, an area less than in size. A 1999 study estimated between 396 and 461 individuals, including adults and juveniles, based on mark-recapture data. Although there are no permanent human settlements on Sombrero, increased rodent populations such as introduced mice may put pressure on the lizards. Flooding and

sea level rise Globally, sea levels are rising due to human-caused climate change. Between 1901 and 2018, the globally averaged sea level rose by , or 1–2 mm per year on average.IPCC, 2019Summary for Policymakers InIPCC Special Report on the Ocean and Cry ...

may also threaten the species. The population appears to be thriving, possibly due to its isolation from human activity..

References

* * {{Taxonbar, from1=Q28949643, from2=Q632857 Pholidoscelis Reptiles described in 1861 Lizards of the Caribbean Reptiles of Anguilla Endemic fauna of Anguilla Taxa named by Edward Drinker Cope