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A Guide to the Amphibians
and Reptiles of California





Northern Intergrades of Subspecies of
Aquatic Gartersnake -Thamnophis atratus

 






Aquatic Gartersnake California Range MapRange in California: Gray

Click the map for a guide
to the other subspecies.








observation link

 

North of the San Francisco Bay, there is a very large range of intergradation between three subspecies of Thamnophis atratus:

Thamnophis atratus atratus - Santa Cruz Gartersnake
Thamnophis atratus hydrophilus - Oregon Gartersnake
Thamnophis atratus zaxanthus - Diablo Range Gartersnake

The snakes in this area were formerly classified as Thamnophis atratus aquaticus (or Thamnophis couchii aquaticus.)
This subspecies is no longer recognized.


Aquatic Gartersnake Intergrade Aquatic Gartersnake Intergrade Aquatic Gartersnake Intergrade
  Adult, Marin County  
Aquatic Gartersnake Intergrade Aquatic Gartersnake Intergrade Aquatic Gartersnake Intergrade
Adult, Marin County, left, with sympatric T. e. terrestris on right. Adult, Solano County
Aquatic Gartersnake Intergrade Aquatic Gartersnake Intergrade Aquatic Gartersnake Intergrade
Adult, Marin County Adult, Marin County Adult from Marin County Headlands, just northwest of the Golden Gate Bridge
© Zach Lim
     
Sympatric Gartersnakes
Gartersnakes Gartersnakes Valley Gartersnake

Marin County snakes:
Coast Gartersnake on top.
Aquatic Gartersnake on bottom.

Marin County snakes:
Aquatic Gartersnake on left.
Coast Gartersnake on bottom.
Three species found at the same Marin County location, including Thamnophis atratus, and Thamnophis elegans.
© Luke Talltree
     
Habitat
Aquatic Gartersnake Intergrade Habitat Aquatic Gartersnake Intergrade Habitat Aquatic Gartersnake Intergrade Habitat
Habitat, Marin County








Habitat, Solono County Habitat, Marin County

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