Nerodia ID issue

[skinheaddave]

I am having problems IDing three very small (thinner than a pencil) Nerodia sp. Does anyone have either a really good comparison of juvenile patterns or, better yet, a key that relies on scale counts rather than colour. I do not know the original collection locale of these -- though I assume they are WC because of their price.

Cheers,
Dave

 

[Wade]

Do you have the Peterson Guide to the Reptiles and Amphibians of Eastern North America by Roger Conant? I don't have my copy at hand at the moment, but I think it does have pics of juveniles. The most recent edition has the best pictures for ID purposes. I think the important taxinomic features are also described.

Wade

 

[skinheaddave]

Wade,

I actually do have it, and have used it to narrow down the field. There are only pictures for a couple juveniles, though, and the scale information is not complete for the genus. Still, it has proven my most valuable resource to date. I suspect I have either taxispilota or rhombifer. The problem is that I have one that definitely has the taxispilota pattern, one that definitely has the rhombifer patern and one that looks like an intermediate. With only vague descriptions of juvenile colouration there isn't much to work on.


EDIT: I just checked plate 21 and realized that all three specimens show the ventral colouration of N.taxispilota. So perhaps it is an example of juvenile variation (even a chance of hybridization, I suppose, though plain old variation seems the most parsimonious explanation).

Cheers,
Dave