Posted by:
b1eagar
at Fri Sep 9 01:06:48 2005 [ Email Message ] [ Show All Posts by b1eagar ]
Stebbins is a good general field guide but his field guide is not the best for keying out some subspecies. That is partly why he has dropped so many subspecies in his newest edition. As his field guide has been revised over the years, so have the subspecies descriptions and our knowledge of the snakes across a wide area. Many of the old subspecies descriptions don't hold true for many species across their ranges. It is best to go to the species desriptions published in scientific journals to get more detailed key information. That is where Stebbins is getting his information from. It would be nice if Stebbins provided a better bibliography than he has in the past to aid those who wish to find out more in knowing where to look.
Many herpetologists have examined and re-examined the western Sirtalis group including Fitch, Tanner, Rossman, Ford and Seigel. I don't have time at the moment to look for the references for you. Perhaps in the winter I will post a more detailed explanation.
>>I am interested in what criteria you are using to distinguish between concinnus and fitchi.
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>>Stebbins writes that the Oregon Red-Spotted subspecies may or may not have lateral stripes. In fact he states that the lateral stripe is only occasionally or sometimes missing. Of the Valley Garter he states the tops of their heads are black, brown, or dark grey. The other difference cited between the two subspecies is the color of the ventrals.
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>>Red-Spotted: Black ground color extends onto belly.
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>>Valley: Black on belly usually confined to the tips of the ventrals
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>>This is all consistent with all the other material I have found. I have not found anything contradictory nor have I found anything more in depth. The relationship between the Calif Red-Sided, the Red-Spotted, and the Valley Garter is interesting but a bit hazy. For that matter I wonder how you’d distinguish a Valley from a Common Red-Sided if no location data was available since the latter also has a dark head. Do you know of any herpetologists or taxonomists that have written in greater and more precise detail on distinguishing concinnus from fitchi?
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RE: Here is a Valley Garter from the Gorge. - b1eagar, Fri Sep 9 01:06:48 2005