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Thamnophis couchii (KENNICOTT, 1859)

IUCN Red List - Thamnophis couchii - Least Concern, LC

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Higher TaxaColubridae (Natricinae), Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes)
Common NamesE: Western Aquatic Garter Snake, Sierra Garter Snake
G: Westliche Strumpfbandnatter, Couchs Strumpfbandnatter 
SynonymEutaenia couchii KENNICOTT in BAIRD 1859: 10
Thamnophis ordinoides couchii — VAN DENBURGH & SLEVIN 1921: 29
Thamnophis ordinoides couchii — STEJNEGER & BARBOUR 1933: 123
Thamnophis couchii — FITCH 1984
Thamnophis couchii — STEBBINS 1985: 204
Thamnophis couchii — CROTHER 2000
Thamnophis couchii — WALLACH et al. 2014: 720 
DistributionUSA (Oregon, California)

Type locality: Pitt River, California  
Reproductionovoviviparous. May be parthenogenetic. 
TypesHolotype: USNM 866, adult female (J.S. Newberry). 
DiagnosisDEFINITION (couchii s.l.): “This is a medium-sized to large (32-108 cm S-V) Thamnophis characterized by: keeled dorsal scales (except those of lowest row) in 21-23-21-19-17, 21-19-17, or 19-21-19-17 (or 15) rows, reduced from maximum of 23 by loss, successively, of 5th, 6th and 4th; 8 supralabials, 4th and 5th bordering orbit, 6th and 7th relatively low with suture between them oblique; 1 or occasionally 2 pairs of preoculars, usually 3 pairs of postoculars; posterior genials markedly longer than anterior in most; internasals longer than broad, narrow anteriorly; 140-187 ventrals, 61-97 subcaudals, vertebral stripe usually faint, pale tan, sometimes confined to anterior end of body, bright yellow in some populations, totally absent in others; lateral stripes on 3rd and 4th scale rows, usually dull yellow or tan, sometimes absent; pale, creamy yellow or green flecks mainly confined to skin between scales in dorsolateral area, setting off dark spots in two alternating series between dorsal and lateral stripes; ventral surface dull white, yellow or gray tinted with pink or purple posteriorly; tip of retracted hemipenis at about 14th (13th to 17th) subcaudal; males average 82% offemale length S-V and 55% of female weight, have tails about 24-27% of total length (vs 22-25% in females), and average 3-6 more ventrals and 8-13 more subcaudals than females.” (Fitch 1984)

DEFINITION (as subspecies, couchii couchii): “Adult length S-V 42-75 cm, lateral stripes distinct, dull yellow (sometimes absent), vertebral stripe usually poorly developed, mostly confined to vertebral scale row and to anterior part of body, more distinct in some; dorsolateral area brown with two alternating rows of squarish black spots that are somewhat larger than interspaces and hence have overlapping corners in a checkered pattern; ventral surface ochraceous, usually marked with black; iris uniform yellowish brown; scale rows 21 on forebody (rarely increased to a maximum of 22 or 23 by addition of a very short 5th row on one or both sides), reduced posteriorly to 19 and then to 17; snout narrow and pointed; supralabials low, those behind eye separated by slanting sutures; ventrals 163-180 in females, 170-184 in males; subcaudals 69-91 in females, 79-98 in males.” (Fitch 1984) 
EtymologyNamed after Darius Nash Couch (1822-1897), a U.S. Army officer and a General during the Civil War. See Beolens et al. 2011: 60 for more details. 
  • Bellemin, Jeanne M.;Stewart, Glenn R. 1977. Diagnostic characters and color convergence of the garter snakes Thamnophis elegans terrestris and Thamnophis couchii atratus along the Central California coast. Bulletin of the Southern California Academy of Sciences 76 (2): 73-84
  • Beolens, Bo; Michael Watkins, and Michael Grayson 2011. The Eponym Dictionary of Reptiles. Johns Hopkins University Press, Baltimore, USA - get paper here
  • Booth, Warren; Gordon W. Schuett 2015. The emerging phylogenetic pattern of parthenogenesis in snakes. Biological Journal of the Linnean Society 118 (2): 172–186, DOI: 10.1111/bij.12744
  • Boundy, Jeffrey 1990. Biogeography and variation in southern populations of the garter snake Thamnophis atratus, with a synopsis of the T. couchii complex. M.A. Thesis San Jose State University: ix, 105
  • Bourguignon, T. 2002. Strumpfbandnattern: Herkunft - Pflege - Arten. E. Ulmer Verlag, 125 pp.
  • 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 1984. Thamnophis couchii (Kennicott). Western aquatic garter snake. Catalogue of American Amphibians and Reptiles ( 351: 1-3 - get paper here
  • Germano, David J. and P.T. Smith 2010. MOLECULAR EVIDENCE FOR PARTHENOGENESIS IN THE SIERRA GARTER SNAKE, THAMNOPHIS COUCHII (COLUBRIDAE). Southwestern Naturalist 55(2):280–282 - get paper here
  • Grübner, Daniel 2014. Farbformen bei Strumpfbandnattern. Ein Blick in die Vergangenheit, das Heute und die Trends von Morgen. Draco 16 (57): 16-27 - 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. 1859. Eutaenia couchii. In: Williamson & Abbot, Explorations for a railroad route, from the Sacramento Valley to the Columbia River. U. S. Pacif. Railroad Surv. 10, Pt.4, p. 10 - get paper here
  • Lind, A.J. & H.H. Welsh, Jr. 1990. Predation by Thamnophis couchii on Dicamptodon ensatus Journal of Herpetology 24 (1): 104-106. - 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
  • REIMCHE, JESSICA S.; ROBERT E. DEL CARLO, EDMUND D. BRODIE JR, JOEL W. MCGLOTHLIN, KAREN SCHLAUCH, MICHAEL E. PFRENDER, EDMUND D. BRODIE III, NORMAND LEBLANC & CHRIS R. FELDMAN. 2022. The road not taken: Evolution of tetrodotoxin resistance in the Sierra garter snake (Thamnophis couchii) by a path less travelled. Molecular Ecology 31(14): 3827–3843. - 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
  • Stebbins,R.C. 1985. A Field Guide to Western Reptiles and Amphibians, 2nd ed. Houghton Mifflin, Boston
  • Stejneger, L.H., and T. Barbour. 1933. A Check List of North American Amphibians and Reptiles, third edition. Harvard University Press, Cambridge, 185 pp. - get paper here
  • Van Denburgh,J. and Slevin,J.R. 1921. A list of the amphibians and reptiles of Nevada, with notes on the species in the collection of the academy. Proc. Cal. Acad. Sci. (4) 11 (2): 27-38 - get paper here
  • 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.
  • Westphal, Michael F. 2006. On the Evolution of Correlated Color Traits in Garter Snakes. PhD Dissertation, Oregon State University, 180 pp. - get paper here
  • Wiseman, Kevin D. 2014. Thamnophis couchii (Sierra gartersnake) predation. Herpetological Review 45 (3): 520 - get paper here
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