I bought the Garstka paper on the mexicana group a few years back, and have re-read it in the last day or two. It's amazing that it's been 23 years since the last really significant paper on mexicana was published (excluding the new paper on l. webbi). In his 1982 paper, Garstka breaks the mexicana group into 3 species with no sub-species (l. alterna, l. ruthveni, l. mexicana). He gives good reasons to split alterna from mexicana, and to split ruthveni from arcifera. But the reasons to drop the sub-species status of greeri, thayeri, and mexicana are kind of lame. His hypothesis of mimicry doesnt hold up very well. He straight out admits that greeri don't really look similar to any rattlesnake, or coral snake in their habitat. His explanation of the variability of mexicana from Nuevo Leon (thayeri to us!) is kind of weak too. I have always heard that taxonomist can be divided into "splitters" that want to create new species and ssp. and "lumpers" that want to combine them. Garstka did both in 1982. The science behind it all is fascinating and it's a great read for the couple of bucks it costs to get.
Greg
