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Reptilia    Squamata (part-other lizards)    Xantusiidae  
Island Night Lizard
Xantusia riversiana Cope, 1883
zan-TOO-see-ah — riv-er-see-AN-uh
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SSAR 9th Edition Comments:
 The taxonomic distinction between populations of X. riversiana on San Nicolas Island (X. r. riversiana) and those on San Clemente and Santa Barbara Islands (X. r. reticulata) has been supported by analyses of both DNA sequences (Noonan et al., 2013, Molecular Phylogenetics and Evolution 69: 109–122) and morphology (Adams et al., 2018, Copeia 106: 550–562; Grismer et al., 2022, Vertebrate Zoology 7: 1–27). (de Queiroz, Kevin and Lauren M. Chan. 2025. Squamata (excluding snakes) – Lizards. Pages 23-37 in Kirsten E. Nicholson (Editor), Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, with Comments Regarding Confidence in Our Understanding, 9th Edition. Society for the Study of Amphibians and Reptiles, Lawrence, Kansas. 87 pp.)

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Open icons indicate questionable records, including those with coordinate uncertainty greater than 10,000 m (approximately 6 miles). Click a marker to view metadata.
Occurrences:; 2,730 Total; 2,635 Museum; 95 Other

The locality database contains 8,094,832 records, and geographic and taxonomic errors exist. Logged-in, registered users may report a potential issue directly from the marker popup.
Shaded range maps are based on curated specimens and provided gratis by CNAH. (Version: 2023.04.10.13.42.07)
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Province/State Distribution:
United States: California

Taxonomic Etymology:
Named for a collector whose fieldwork on the Channel Islands helped expand knowledge of California’s unique flora and fauna.
Xantusia — Named in honor of John Xantus de Vesey (1825–1894), a Hungarian-born zoologist and collector who worked in California and Mexico. 
riversiana — A patronym honoring James P. Rivers (1824–1913), an English-born American naturalist and botanical collector. Collected extensively in California and on the Channel Islands, including San Clemente Island. Latinized feminine genitive form of “Rivers,” meaning “of Rivers” — a standard form when the genus name (Xantusia) is feminine.

First instance(s) of published English names:
Island Night Lizard (Xantusia riversiana: Van Denburgh, John. 1897. The reptiles of the Pacific Coast and Great Basin: An account of the species known to inhabit California, and Oregon, Washington, Idaho, and Nevada. Occasional Papers of the California Academy of Sciences 5():9-236);


Selected References:
1883 Cope, Edward D. Notes on the geographical distribution of Batrachia and Reptilia in western North America. Proceedings of the Academy of Natural Sciences of Philadelphia 35:10-35
1986 Crother, Brian I., Michael M. Miyamoto, and William F. Presch. Phylogeny and biogeography of the lizard family Xantusiidae. Systematic Zoology 35(1):37-45
1991 Fellers, Gary M. and Drost, Charles A. Xantusia riversiana. Catalogue of American Amphibians and Reptiles (518):1-4
2013 Noonan, Brice P., Jennifer B. Pramuk, Robert L. Bezy, Elizabeth A. Sinclair, Kevin de Queiroz, and Jack W. Sites, Jr. Phylogenetic relationships within the lizard clade Xantusiidae: Using trees and divergence times to address evolutionary questions at multiple levels. Molecular Phylogenetics and Evolution 69(2013):109-122

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