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Thamnophis postremus SMITH, 1942

IUCN Red List - Thamnophis postremus - Least Concern, LC

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Higher TaxaColubridae (Natricinae), Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes)
Common NamesE: Tepalcatepec Valley Gartersnake
S: Jarretera de Tepalcatepec 
SynonymThamnophis eques postremus SMITH 1942: 109
Thamnophis eques postremus — SCHMIDT 1947
Thamnophis cyrtopsis postremus — SMITH 1951: 140
Thamnophis postremus — ROSSMAN et al. 1996
Thamnophis postremus — DE QUEIROZ et al. 2002
Thamnophis postremus — LINER 2007
Thamnophis postremus — WALLACH et al. 2014: 724 
DistributionMexico (Michoacan)

Type locality: El Sabino, Michoacan.  
TypesHolotype: FMNH 120235 (was EHT-HMS 5275, H.M. Smith). Collected by: E. H. Taylor and H.M. Smith. Paratypes: (n=3) FMNH 5274, 5285-6, all females, from Uruapan, Michoacan. 
DiagnosisDiagnosis. Similar to e. eques, except ventrals fewer, 138 to 141 in the only specimens known (4 females); caudals 71 to 72; supralabials 7 to 8; lateral light stripes not apparent; middorsal stripe but very little lighter than ground color, scarcely or not evident; dark spots very much reduced, al­ ternating with each other in two series on either side; middorsum not traversed by spots; outer row of dark spots on first and second scale rows greatly reduced, generally scarcely visible; no distinct dark spots on venter. (Smith 1942: 109).

DEFINITION. “There is a black nuchal collar. The vertebral stripe is indistinct, usually not extending on tail. Pale brown dorsolateral areas have a contrasting pattern of relatively small, dark alternating blotches extending the length of the body. The first three scale rows are pale, mostly unicolor, but often have scattered, small black flecks. Black supralabial markings are well developed, with a characteristic large comma or thorn-shaped mark on the next to last suture. Seven supralabials (60%) are more frequent than eight (37%). There is often more than one black mark on the infralabial sutures. Small, paired black spots usually occur laterally on ventrals. Ventral scales (males, mean 146, range 142-151; females, 140, 136-142) are the fewest of any subspecies.” (Webb 1980) 
  • Heimes, P. 2016. Snakes of Mexico. Chimaira, Frankfurt, 572 pp
  • Liner, Ernest A. 2007. A CHECKLIST OF THE AMPHIBIANS AND REPTILES OF MEXICO. Louisiana State University Occasional Papers of the Museum of Natural Science 80: 1-60 - 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
  • 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.
  • Schmidt, Karl P.;Shannon, Frederick A. 1947. Notes on amphibians and reptiles of Michoacan, Mexico. Zoological Series of Field Museum of Natural History 31 (9): 63-85
  • Smith, Hobart M. 1942. The synonymy of the garter snakes (Thamnophis), with notes on Mexican and Central American species. Zoologica, Scientific Contributions of the New York Zoological Society 27 (3 and 4): 97-123 - 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.
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