You are here » home advanced search search results Thamnophis atratus

Thamnophis atratus KENNICOTT, 1860

IUCN Red List - Thamnophis atratus - Least Concern, LC

Can you confirm these amateur observations of Thamnophis atratus?

Add your own observation of
Thamnophis atratus »

Find more photos by Google images search: Google images

Higher TaxaColubridae (Natricinae), Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes)
SubspeciesThamnophis atratus atratus (KENNICOTT 1860)
Thamnophis atratus hydrophilus FITCH 1936
Thamnophis atratus zaxanthus BOUNDY 1999 
Common NamesE: Pacific Coast Aquatic Garter Snake, Santa Cruz Garter Snake
atratus: Santa Cruz Garter Snake
hydrophilus: Oregon (Gray) Garter Snake
zaxanthus: Diabolo Garter Snake
G: Santa-Cruz-Strumpfbandnatter 
SynonymThamnophis atratus (KENNICOTT 1860: 296)
Eutaenia atrata KENNICOTT in COOPER 1860
Thamnophis elegans aquaticus FOX 1951: 493
Thamnophis couchi atratus — STEBBINS 1985: 206
Thamnophis atratus — ROSSMAN & STEWART 1987
Thamnophis atratus — CROTHER 2000
Thamnophis atratus — CROTHER et al. 2012
Thamnophis atratus — WALLACH et al. 2014: 720

Thamnophis atratus atratus (KENNICOTT 1860)
Eutaenia atrata KENNICOTT in COOPER 1860: 296
Thamnophis elegans atratus — FOX 1951
Thamnophis atratus atratus — CROTHER 2000
Thamnophis atratus atratus — CROTHER et al. 2012

Thamnophis atratus hydrophilus FITCH 1936
Thamnophis ordinoides hydrophila FITCH 1936
Thamnophis couchii hydrophila — FOX & DESSAUER 1964: 266
Thamnophis couchii hydrophilus — FITCH 1984
Thamnophis atratus hydrophilus — ROSSMAN et al. 1996
Thamnophis atratus hydrophilus — CROTHER 2000
Thamnophis atratus hydrophilus — CROTHER et al. 2012

Thamnophis atratus zaxanthus BOUNDY 1999
Thamnophis atratus zaxanthus — CROTHER 2000
Thamnophis atratus zaxanthus — CROTHER et al. 2012 
DistributionUSA (coastal C California, SW Oregon)

atratus: USA (California); Type locality: "California." Listed as "San Francisco, California," by Fitch, 1940: 89, and Cochran, 1961: 181.

hydrophilus: USA (S Oregon, N California)

zaxanthus: USA (California: Inner Coast Range from Napa and Solano to Santa Barbara counties, and the Santa Lucia Range). Type locality: 2 miles S Gilroy Hot Springs, Santa Clara County, California.  
TypesLectotype: USNM 970, (R.D. Cutts, 1854), designated by Fitch, 1940: 89.
Holotype: MVZ 207940 (adult female) [zaxanthus]
Holotype: MVZ 48196 (adult male) [aquaticus]
Holotype: MVZ 18127 (adult male) [hydrophilus] 
DiagnosisDiagnosis: A short, somewhat stout garter snake with pointed snout and remarkably uniform head scales: almost always 8 upper labials, 10 lower labials, 1 preocular, and 3 postoculars on each side (table 2). Internasals usually longer than broad, pointed anteriorly, and in narrow contact with rostral; sixth and seventh upper labials relatively large and taller than long, resembling'those of terrestrial races rather than those of other aquatic races, in which rows of upper labials are * practically straight (Fox 1951: 489)

Coloration: Broad orange or orange-yellow dorsal stripe usually covers at least 0.66-1.66 rows of scales, frequently 3 full scale rows, and occasionally only central row involved. Lateral stripes absent in blue-black individuals from San Francisco peninsula, but elsewhere usually present and conspicuous pale yellow.
Top of head usually olive, dark olive, or blue black; chin and throat bright lemon yellow, this color usually extending to or over lower labials; upperlabials generally pale yellow. Iris very dark, almost black except for loose silvery network in most specimens. Dorsal ground color blue black, black, or dark olive with distinct or indistinct black spots; no red spotting. Ventral surface varies froih deep blue to pale blue or green; in most specimens central part of each ventral scute irregularly blotched with Salmon-Orange or Capucine Orange. Blotching begins in anterior third'of body and increases posteriorly (Fox 1951: 490)

Scalation: Maximum number of body scale rows, 19; always 19 at neck and thoracic re­gions; almost always 15 at posterior end of body, rarely 17. Ventral scutes range from 145 to 169 in males and from 138 to 167 in females; caudal scutes range from 70 to 89 in males and-64 to 82 in females (Fox 1951: 490)

Comparisons: T. e. atratus intergrades with T. e. aquations and occupies parts of the ranges of T. e. terrestris and T. e. hammondii. For compari­sons with aquaticus and terrestris, see sections dealing with these forms. In geographically overlapping atratus and hammondii color differences very distinct: dorsal stripe in atratus broad and brightly colored, in hammondii absent or confined to neck region; dorsal ground color black or olive drab in atratus, brown or olive gray in hammondii; dorsolateral blotches distinct and well represented in hammondii, obscure in atratus. Hammondii lacks lemon-yellow throat character­istic of atratus.
Both races have pointed internasals longer than wide, a character common throughout the aquatic group. Sixth and seventh supralabials relatively large and taller than long in atratus, longer than tall in hammondii. Nineteen and 15 scale rows at thoracic region and posterior end of body, respectively, characteristic of atratus; 21 and 17 characteristic of hammondii. In hammondii, average numbers of gastrosteges and urosteges higher than in atratus. In hammondii, preoculars frequently divided and eyes large; in atratus, preoculars rarely divided, diameter of eye small (Fox 1951: 490)

See also Fitch 1984 for another definition.

DEFINITION (aquaticus): “Vertebral stripe bright yellow or orange yellow, including vertebral scale row and from about half to all of each paravertebral row; lateral stripes distinct, light olive buff, occasionally absent in some populations; ventral surface light blue or green with varying amounts of pale salmon in central area, increasing posteriorly; iris gray or drab; dorsal scale rows 19-19-17 or 19-19· 15, rarely 19-21-19-17; ventrals 142-167 in females, 147-167 in males; subcaudals 63-82 in females, 74-93 in males.” (Fitch 1984)

DEFINITION (hydrophilus): “Vertebral stripe usually narrow and dull or faint, sometimes absent; lateral stripes dull yellow, sometimes faint or absent; dorsal ground color bluish gray to brown, with a checkered pattern of two alternating rows of dark spots; ventral surface white anteriorly to gray posteriorly, immaculate or nearly so, tinted with pink or purple which increases posteriorly; iris uniformly gray or brown; scale rows usually 19-21-19-17, with reduction to 15 rows at the posterior end of the body in some specimens; ventrals 140-168 in females, 150-171 in males; subcaudals 61-84 in females, 76-88 in males.” (Fitch 1984) 
CommentRossman and Stewart (1987) recommended against recognizing T. a. aquaticus. RODRIGUEZ-ROBLES e al. 2003 stated that aquaticus is a Thamnophis a. atratus x T. a. hydrophilus intergrade. 
  • Allen, W. L., R. Baddeley, N. E. Scott-Samuel, and I. C. Cuthill. 2013. The evolution and function of pattern diversity in snakes. Behav. Ecol. 24:1237– 1250
  • Bol, S. 2007. Verzorging en kweek van de Santa Cruz kousebandslang, Thamnophis atratus atratus. Lacerta 65 (5): 200-217 - get paper here
  • Boundy, J. 1999. Systematics of the garter snake Thamnophis atratus at the southern end of its range. Proc. Cal. Acad. Sci. 51 (6): 311-336 - get paper here
  • Bourguignon, T. 2002. Strumpfbandnattern: Herkunft - Pflege - Arten. E. Ulmer Verlag, 125 pp.
  • Bruchmann, H. 2006. Freilandbeobachtungen an Strumpfbandnattern in Nordamerika. Draco 6 (25): 86-93 - get paper here
  • Burbrink FT, Futterman I. 2019. Female‐ biased gape and body-size dimorphism in the New World watersnakes (tribe: Thamnophiini) oppose predictions from Rensch's rule. Ecol Evol. 00:1–10
  • Crother, B. I. (ed.) 2012. Standard Common and Current Scientific Names for North American Amphibians, Turtles, Reptiles, and Crocodilians, Seventh Edition. Herpetological Circular 39: 1-92
  • Fitch, H. S. 1936. Amphibians and reptiles of the Rouge River Basin, Oregon. American Midland Naturalist 17: 634-652 - get paper here
  • Fox, W. 1951. Relationships among the garter snakes of the Thamnophis elegans rassenkreis. Univ. California Publ. Zool. 50: 485-530
  • Grübner, D. 2006. Die seltener beobachteten Strumpfbandnattern. Draco 6 (25): 66-76 - get paper here
  • HALLAS, JOSHUA M.; THOMAS L. PARCHMAN & CHRIS R. FELDMAN. 2021. Phylogenomic analyses resolve relationships among garter snakes (Thamnophis: Natricinae: Colubridae) and elucidate biogeographic history and morphological evolution. Molecular Phylogenetics and Evolution 107374. [2022 in print] - get paper here
  • Hallmen, M. & Chlebowy, J. 2001. Strumpfbandnattern. Natur und Tier Verlag (Münster), 192 pp. - get paper here
  • Kennicott, R. 1860. Zoological report. No. 4. Report upon the reptiles collected on the survey. In: Stevens, I.I. (Ed.), Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean, made under the direction of the Secretary of War, in 1853-5. Route ne - get paper here
  • Parker, Michael S. and Emma Rose Parker. 2011. Thamnophis atratus hydrophilus (Oregon gartersnake) diet. Herpetological Review 42 (3): 445 - get paper here
  • Preston, Daniel L. and Pieter T. J. Johnson 2012. Importance of Native Amphibians in the Diet and Distribution of the Aquatic Gartersnake (Thamnophis atratus) in the San Francisco Bay Area of California. Journal of Herpetology 46 (2): 221-227. - get paper here
  • Queiroz, Alan de; Robin Lawson and Julio A. Lemos-Espinal 2002. Phylogenetic Relationships of North American Garter Snakes (Thamnophis) Based on Four Mitochondrial Genes: How Much DNA Sequence Is Enough? Molecular Phylogenetics and Evolution 22: 315-329 - get paper here
  • Rodríguez-Robles, Javier A., Good, David A., Wake, David B. 2003. Brief History of Herpetology in the Museum of Vertebrate Zoology, University of California, Berkeley, with a List of Type Specimens of Recent Amphibians and Reptiles. UC Publications in Zoology, 119 pp. - get paper here
  • Rossman, Douglas A.; Ford, Neil B. & Seigel, Richard A. 1996. The Garter Snakes: Evolution and Ecology. University of Oklahoma Press, Norman, OK, xx + 332 + pp.
  • Rossman,D.A. & Stewart,G.R. 1987. Taxonomic reevaluation of Thamnophis couchii (Serpentes: Colubridae). Occ. Pap. Mus. Zool. Louisiana Sata Univ. (63): 1-25 - get paper here
  • Sleijpen, Fons 2013. Picture: Thamnophis atratus atratus, adult, female. Litteratura Serpentium 33 (4): 330 - get paper here
  • Stebbins,R.C. 1985. A Field Guide to Western Reptiles and Amphibians, 2nd ed. Houghton Mifflin, Boston
  • Wallach, Van; Kenneth L. Williams , Jeff Boundy 2014. Snakes of the World: A Catalogue of Living and Extinct Species. [type catalogue] Taylor and Francis, CRC Press, 1237 pp.
  • Welsh, H.H., Jr., C.A. Wheeler & A.J. Lind 2010. Spatial Ecology of the Oregon Gartersnake, Thamnophis atratus hydrophilus, in a Free-Flowing Stream Environment Copeia 2010 (1): 75-85. - get paper here
External links  
Is it interesting? Share with others:

As link to this species use URL address:

without field 'search_param'. Field 'search_param' is used for browsing search result.

Please submit feedback about this entry to the curator