Spondylurus nitidus

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA REPTILIA SQUAMATA SCINCIDAE

Scientific Name: Spondylurus nitidus
Species Authority: (Garman, 1887)
Common Name(s):
English Puerto Rican Skink
Synonym(s):
Mabuia nitida Garman, 1887
Taxonomic Notes: Mabuya nitidus was removed from long synonymy with Mabuya sloanii by Hedges and Conn (2012), who redescribed this species and assigned it to Spondylurus. S. nitidus, which was at the time known only from historical material, was not included in these authors' genetic analysis, however molecular work has since confirmed its specific validity (S.B. Hedges, unpubl. data). The identity of a presumably extinct skink from Vieques is unknown, as several species are now known to occur in Puerto Rico (Hedges and Conn 2012). It may have been a population of S. nitidus or S. culebrae (or even the Virgin Islands endemic S. sloanii) (Hedges and Conn 2012), however the possibility also exists that the report referred to a species endemic to Vieques (Hedges and Conn 2012). A reference to mabuyine skinks being "relatively common" on Vieques (Rivero 1998), is thought likely to be in error, as no specimens exist or have been reported in extensive recent surveys, and mabuyine skinks were unknown to the island's inhabitants in 1931 (Hedges and Conn 2012). Genetic research is needed to clarify the appropriate taxonomic status of populations from islands off Puerto Rico (Hedges and Conn 2012).

Assessment Information [top]

Red List Category & Criteria: Endangered B1ab(i,ii,v) ver 3.1
Year Published: 2013
Date Assessed: 2013-08-13
Assessor(s): Hedges, B.
Reviewer(s): Bowles, P.
Justification:
Listed as Endangered on the basis that this species has an estimated extent of occurrence of approximately 750 km2, it occurs as a severely fragmented population, and is subject to a continuing (but not presently quantifiable) decline in the number of mature individuals, and presumably in its extent of occurrence and area of occupancy, mainly as a result of predation by introduced mongoose. Recent surveys across much of Puerto Rico have recorded this species only in one locality and further research into its distribution and rates of population decline may justify listing this species as Critically Endangered.

Geographic Range [top]

Range Description:This species is endemic to Puerto Rico, occurring on the main island and the satellite islands Cayo Luis Peña, Cayo Norte, Culebra, and Icacos (Hedges and Conn 2012). A literature record exists from the satellite island Desecheo (Hedges and Conn 2012). In Puerto Rico itself, it has been reported from several localities close to and along the island's northern and southern coasts (Hedges and Conn 2012). A recent report from Guajataca State Forest in the island's northwest is at 221 m asl. (Sanchez 2013). It may occur slightly more widely in the Quebradillas area (where Guajataca is located) based on anecdotal observations, however recent surveys in several other parts of the island have failed to record it (A. Sanchez pers. comm. 2013). It has an estimated extent of occurrence of approximately 750 km2.
Countries:
Native:
Puerto Rico (Puerto Rico (main island))
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population: This species appears to be rare - intensive herpetological survey efforts over the past fifty years have yielded only a few specimens, and few specimens could be located in museum collections (Hedges and Conn 2012). The population appears to be declining and severely fragmented, primarily due to introduced predators, and to a lesser extent also habitat loss.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: This species has been described as favouring dense clumps of Opuntia cacti as shelter sites and as exhibiting an association with arid and semi-arid areas (Hedges and Conn 2012 and refs therein). Most specimens have been taken from rock fissures, beneath rocks or cacti, or at the base of coconut palms (Rivero 1998). By contrast, Sanchez (2013) recorded the species from humid limestone forest, where it was typically active in the morning and basking on exposed rocks, leaf litter or fallen logs. On Desecheo (where only Spondylurus nitidus occurs), it appears to preferentially emerge from shelter sites on cloudy days (Rivero 1998), although this too appears not to be the case for recently-reported S. nitidus from the main island (Sanchez 2013). It is a viviparous species, and one female was found to contain two developing young (Hedges and Conn 2012).
Systems: Terrestrial

Use and Trade [top]

Use and Trade: There is no known use or trade in this species.

Threats [top]

Major Threat(s): Declines in this species are thought likely to be the result of predation by introduced mongoose, responsible for declines and extinctions in lizards elsewhere in the Caribbean (Hedges and Conn 2012). The mongoose was probably introduced to Puerto Rico in the late 19th Century; at the same time it was introduced to many smaller islands in the Caribbean, coincident with the last known records of several skink species (Hedges and Conn 2012). An enigmatic skink possibly conspecific with Spondylurus nitidus was reported from Vieques in 1868 but by 1931, following mongoose introduction, it was absent and local residents were unfamiliar with it (Hedges and Conn 2012 and refs therein). Sanchez (2013) reports that mongoose were not observed at the Guajataca State Forest, despite repeated surveys since September 2011, which may explain the skink's continued survival and apparent relative abundance at this locality. The species faces secondary pressures from other exotic mammals, mainly black rats that are ubiquitous in all habitats and elevations in Puerto Rico, and possibly from habitat conversion due to urbanization and agricultural expansion (Hedges and Conn 2012).

Conservation Actions [top]

Conservation Actions: This species is found in a number of protected areas, however as it faces threats primarily from invasive mammals these offer no effective protection and no other conservation measures are in place to protect this skink (Hedges and Conn 2012). Hedges and Conn (2012) propose captive breeding on the basis that invasive mammals are impossible to eradicate from an island as large as Puerto Rico, and with the recent discovery of a surviving wild population (Sanchez 2013) this action should be considered a priority. While the genetic validity of this species has recently been confirmed (S.B. Hedges pers. comm. 2013), further research may be required to verify the status of populations on offshore islands (Hedges and Conn 2012).

Bibliography [top]

Hedges, S.B. and Conn, C.E. 2012. A new skink fauna from Caribbean islands (Squamata, Mabuyidae, Mabuyinae). Zootaxa 3288: 1-244.

IUCN. 2013. IUCN Red List of Threatened Species (ver. 2013.2). Available at: http://www.iucnredlist.org. (Accessed: 13 November 2013).

Rivero, J.A. 1978. Los anfibios y reptiles de Puerto Rico. The amphibians and reptiles of Puerto Rico. Universidad de Puerto Rico, Editorial Universitaria.

Rivero, J.A. 1998. Los Anfibios y Reptiles de Puerto Rico / The Amphibians and Reptiles of Puerto Rico. Second edition. Editorial de la Universidad de Puerto Rico, San Juan.

Sanchez, A.J. 2013. Spondylurus nitidus (Puerto Rican Skink). Distribution. Caribbean Herpetology 40(1).


Citation: Hedges, B. 2013. Spondylurus nitidus. In: The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 24 October 2014.
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