CK:
I knew your post dealt with speciation but simply used the C. bottae examples as being somewhat analogous.

Depite the paper by Javier Rodriguez-Robles and others elevating umbratica to the level of species, I believe it this position does not have sufficient support. The morphological features upon which the authors relied are weak at best and may be invalid due to some problems of which they were not aware.

That being said, I am now of the position that the dwarf form (regardless of the mtDNA results), possesses a set of morpholgical features to warrant subspecific distiction. The characteristics of maximum mid dorsal scale count and ventral count appear to be consistent with the factor of lengths. Lower values for these two scalation features are concordant with the dwarf form whereas higher scalation values are associated with the large form immediately north from central Tulare County northward to about south Plumas County and west to include the boas in the Bay Area of central Calif. The feature of dorsal scale count is muddled to the north with another cline of lower maximum mid dorsal counts occurring in specimens from Plumas Co., Calif. northward and eastward.

My reasons for considering that a dwarf form was the original ancestor is based on biological factors. I am not certain as to how you arrived at your interpretation that the dwarf form was likely to be the ancestor to current populations.

You mentioned: "A possible answer to this question comes from the fact that umbratica is the first lineage to branch off from this ancestor."

Further on: "We see that umbratica (the first lineage to branch off) consists only of small morphs and the Sierra Nevada subclade (which branches off later) consists of both large and small morphs. Applying the general principle discussed above to the rubber boas, it is most probable that the small morph is the ancestral morphotype since it is found in umbratica, the oldest lineage and that the large morph evolved later since large morph snakes are found only in the newer lineages (Northwestern and Sierra Nevada subclades)."

I am not certain how you determined that umbratica branched off first and thus is the oldest lineage.

And I agree when you stated the following: "The problem with recognizing umbratica as a new species is that some of the small morph populations, which is morphologically indistinguishable from umbratica even on the basis of adult size would be classified as a different species: bottae."

Richard F. Hoyer

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