Stull considered affinis to be a subspecies of sayi. There is clearly a broad band where sayi and affinis merge and overlap but my question is do these snakes represent intergradient populations or are they hybrids? The lines between what constitutes a species is blurred and depending on which definition is followed they could be either. Where affinis merges with other more western forms of Pits is much more sketchy from what I hear. It is problematic since affinis shares some physical characteristics of both sayi and deserticola and annectans to the west. Clearly these are closely related groups of snakes but how best to define them? Stull considered affinis to be the most generalized form of Pituophis and most likely the ancestral species in which all other forms evolved and radiated from. Morphologically sayi is distinct from catenifer and clearly represents a more specialized form than the western catenifer which are very much generalists.



Interesting discussion!



Phil

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