A Guide to the Amphibians
and Reptiles of California

Sandstone Night Lizard - Xantusia gracilis

Grismer and Galvan, 1986

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Description • Taxonomy • Species Description • Scientific Name • Alt. Names • Similar Herps • References • Conservation Status

Red: Range in California

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Map with California County Names

Red: Close-up of Range in California

Adult, San Diego County

Adult in sandstone crevice, San Diego County © Grigory Heaton

Adult, San Diego County
© Adam G. Clause
Animal captured and handled under state Scientific Collecting Permit and released at point of capture.

The Night Lizards, genus Xantusia, have small granular scales on soft skin.
Xantusia henshawi is shown here.

Habitat

Habitat from a distance,
San Diego County

Habitat, San Diego County

Description

Size

2.0 - 2.8 inches long from snout to vent (5.0 - 7.0 cm). (Lemm 2006)

Appearance

A small flat-bodied lizard with a flattened head, soft skin with fine granular scales, a long thin tail, lidless eyes with vertical pupils, and gular folds.
Similar to and closely related to Xantusia henshawi, but with a narrower head, a body that is shorter between the limbs, and with thinner limbs.

Color and Pattern

The color is white to yellowish, with large dark brown spots on the upper surfaces, and irregular spots and bands on the tail. This species does not exhibit the light and dark phases seen in X. henshawi. It looks more like the light phase of that species but with more light coloring and smaller dark spots.
The underside is white with minute black speckling only on the forepart

Male / Female Differences

Males have enlarged femoral pores.

Life History and Behavior

Activity

Natural history is not well known.
Nocturnal, taking refuge during the day under exfoliating slabs of sandstone, in cracks, and in rodent burrows dug into the sandstone.
More strictly nocturnal than X. henshawi.
Probably active from spring to fall, taking cover during winter.
More terrestrial and less restricted to climbing rocks than X. henshawi.
This species probably developed a more slender body than X. henshawi to allow it to better exploit the wide range of microhabitats found in its sandstone habitat.

Defense

Wary and secretive. Capable of running quickly for short distances to escape.
The tail can break off easily, but it will grow back.
The detached tail wriggles on the ground which can distract a predator from the body of the lizard allowing it time to escape.
More information about tail loss and regeneration.

Diet and Feeding

Diet is not well known but probably is similar to that of X. henshawi, consisting of small invertebrates such as ants, beetles, and bees. Captive individuals have been observed eating the eggs of Leaf-toed Geckos.
One Sandstone night lizard was observed emerging from a crevice at night to prey on various invertebrates, retreating to the crevice after each strike. (Herpetological Review 46(1), 2015)

Reproduction

Reproduction is not well known but breeding probably occurs in May and June with live young born in September.

Habitat

Inhabits a very small area of sandstone and mudstone.

Geographical Range

Endemic to California. Occurs only in the Truckhaven Rocks area of San Diego County, in Anza-Borrego State Park.

Elevational Range

From 790 - 1,000 ft. (240 - 305 m).

Notes on Taxonomy

In 1986 Grismer and Galvan published the first description of this species, classifying it a subspecies of Xantusia henshawi - Xantusia henshawi gracilis - Sandstone Night Lizard. It was elevated to a full species in 2001 by Lovich (2001 Herpetologica 57(4): 470-487).

Alternate and Previous Names (Synonyms)

Xantusia henshawi gracilis - Sandstone Night Lizard (Stebbins 2003)

Conservation Issues (Conservation Status)

Protected from collection by the state and the federal government and by the fact that its known range falls completely within the boundaries of Anza-Borrego State Park where it is also protected.

Taxonomy
Family	Xantusiidae	Night Lizards	Baird, 1858
Genus	Xantusia	Night Lizards	Baird, 1859 “1858”
Species	gracilis	Sandstone Night Lizard	Grismer and Galvan, 1986
Original Description
Xantusia henshawi gracilis - Grismer and Galvan, 1986. from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz
Meaning of the Scientific Name
Xantusia - honors Xantus, John gracilis - Latin - slender - referring to the body shape. from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz
Related or Similar California Lizards
X. henshawi - Granite Night Lizard X. r. reticulata - San Clemente Night Lizard X. vigilis - Yucca Night Lizard X. sierrae - Sierra Night Lizard X. wigginsi - Baja California Night Lizard
More Information and References
California Department of Fish and Wildlife Grismer, L. L., and M. A. Galvan. 1986. A new night lizard (Xantusia henshawi) from a sandstone habitat in San Diego County, California. Trans. San Diego Soc. Nat. Hist. 21(10):155-165. Robert L. Bezy. Night Lizards: Field Memoirs and a Summary of the Xantusiidae. ECO Herpetological Publishing & Distribution. 2019. Stebbins, Robert C., and McGinnis, Samuel M. Field Guide to Amphibians and Reptiles of California: Revised Edition (California Natural History Guides) University of California Press, 2012. Stebbins, Robert C. California Amphibians and Reptiles. The University of California Press, 1972. Flaxington, William C. Amphibians and Reptiles of California: Field Observations, Distribution, and Natural History. Fieldnotes Press, Anaheim, California, 2021. Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003. Lemm, Jeffrey. Field Guide to Amphibians and Reptiles of the San Diego Region (California Natural History Guides). University of California Press, 2006. Bartlett, R. D. & Patricia P. Bartlett. Guide and Reference to the Turtles and Lizards of Western North America (North of Mexico) and Hawaii. University Press of Florida, 2009. Jones, Lawrence, Rob Lovich, editors. Lizards of the American Southwest: A Photographic Field Guide. Rio Nuevo Publishers, 2009. Smith, Hobart M. Handbook of Lizards, Lizards of the United States and of Canada. Cornell University Press, 1946.

Conservation Status
The following conservation status listings for this animal are taken from the January 2024 State of California Special Animals List and the January 2024 Federally Listed Endangered and Threatened Animals of California list (unless indicated otherwise below.) Both lists are produced by multiple agencies every year, and sometimes more than once per year, so the conservation status listing information found below might not be from the most recent lists. To make sure you are seeing the most recent listings, go to this California Department of Fish and Wildlife web page where you can search for and download both lists: https://www.wildlife.ca.gov/Data/CNDDB/Plants-and-Animals. A detailed explanation of the meaning of the status listing symbols can be found at the beginning of the two lists. For quick reference, I have included them on my Special Status Information page. If no status is listed here, the animal is not included on either list. This most likely indicates that there are no serious conservation concerns for the animal. To find out more about an animal's status you can also go to the NatureServe and IUCN websites to check their rankings.
Organization	Status Listing	Notes
NatureServe Global Ranking	G1	Critically Imperiled
NatureServe State Ranking	S2	imperiled
U.S. Endangered Species Act (ESA)	None
California Endangered Species Act (CESA)	None
California Department of Fish and Wildlife	SSC	Species of Special Concern
Bureau of Land Management	None
USDA Forest Service	None
IUCN	VU	Vulnerable

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