The Sombrero ameiva (''Pholidoscelis corvinus''), also known commonly as the Sombrero groundlizard, is a

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), ...

lizard Lizard is the common name used for all Squamata, squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most Island#Oceanic isla ...

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 ...

Teiidae Teiidae is a family of lacertoidean lizards native to the Americas. Members of this family are generally known as whiptails or racerunners; however, tegus also belong to this family. Teiidae is sister to the Gymnophthalmidae, Gymnopthalmidae, and ...

. The species is

endemic Endemism is the state of a species being found only 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 foun ...

Sombrero In English, a , ; ) 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 w ...

, a small, uninhabited island in the

Lesser Antilles The Lesser Antilles is a group of islands in the Caribbean Sea, forming part of the West Indies in Caribbean, Caribbean region of the Americas. They are distinguished from the larger islands of the Greater Antilles to the west. They form an arc w ...

under the jurisdiction of

Anguilla Anguilla is a British Overseas Territories, 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 Sa ...

. The species was originally described in the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

'' Ameiva''.

Description

Adults of ''P. corvinus'' are

melanistic Melanism is the congenital excess of melanin in an organism resulting in dark pigment. Pseudomelanism, also called abundism, is another variant of pigmentation, identifiable by dark spots or enlarged stripes, which cover a large part of the bod ...

, appearing plain brown to slate black, with a dark green to black ventral surface mottled with light blue. The tail is sometimes spotted green. Males have brown flecks on the dorsal surface and browner heads. Males grow to snout-to-vent length (SVL), with females being considerably smaller. It is superficially similar in coloration and scalation to '' P. atratus'' and '' P. corax'', two other melanistic species also found on small, barren islands in the Caribbean. As the islands have similar

habitat In ecology, habitat refers to the array of resources, 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 manifestation of its ...

s, this is likely the result of independent adaptation.

Diet

The diet of ''P. corvinus'' includes the eggs of ground-nesting

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

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 an inventory of the global conservation status and extinction risk of biological ...

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 The sea level has been rising from the end of the last ice age, which was around 20,000 years ago. Between 1901 and 2018, the average sea level rose by , with an increase of per year since the 1970s. This was faster than the sea level had e ...

may also threaten the species. The population appeared to be thriving in the early 2000s, possibly due to its isolation from human activity, then crashed steeply to less than 100 individuals as of 2018 due to a combination of invasive species (primarily mice), severe hurricanes, and general environmental degradation. Mouse eradication and native plant restoration by conservation groups allowed the population to rebound to more than 1,600 individuals as of 2024.

Description

Diet

Conservation

References

Further reading