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The Crotalus durissus-complex
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by Hellemar on July 17, 2004
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Hi...
Can someone please help me out with info about the durissus-complex - is it like this now:
Crotalus durissus cascavella
Crotalus durissus collilineatus
Crotalus durissus cumanensis
Crotalus durissus durissus (former Crotalus durissus dryinus)
Crotalus durissus marajoensis
Crotalus durissus neoleonensis
Crotalus durissus ruruima
Crotalus durissus terrificus
Crotalus durissus trigonicus
Crotalus durissus unicolor
Crotalus durissus vegrandis
Crotalus simus culminatus
Crotalus simus simus (former Crotalus durissus durissus)
Crotalus simus tzabcan
Crotalus totonacus (former Crotalus durissus totonacus)
Henke :)
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RE: The Crotalus durissus-complex
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by CAISSACA on July 19, 2004
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That is the way it has been presented in the new Campbell & Lamar book, except that neoleonensis is not a valid name, and it's dryinas, not dryinus.
Cheers,
Wolfgang
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RE: The Crotalus durissus-complex
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by Snakeman1982 on July 20, 2004
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There are 11 subspecies.
As Dr. Wuster mentioned, neoleonensis is not valid. However, don't forget Crotalus durissus maricelae. It is mentioned in the Campbell/Lamar book.
I was surprised to see the downgrade of Crotalus unicolor to a subspecies of durissus. That isn't going to help its endangered status. There were quite a few changes I am still not sure about. But what a great and thorough book!
Robert Jadin
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RE: The Crotalus durissus-complex
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by CAISSACA on July 20, 2004
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I guess at that stage, we should also mention C.d. pifanorum, yet another South American subspecies of questionable status.
As far as the status of unicolor is concerned, phylogenetically, Campbell & Lamar are spot on: it's a northwestern cumanensis that shrank and faded in the wash - see my 2002 paper in Biology of the Vipers (downloadable from http://biology.bangor.ac.uk/~bss166/ ).
What one actually does with differentiated island endemics like this is a thorny question in taxonomy. No-one is arguing about the hard data, but the interpretation, and how is is translated into nomenclature is more contentious. Some people prefer to see the bigger picture and lump them with their close mainland relatives, others argue that they are differentiated and not in contact with the mainland population,a nd should therfore be called separate species. Take your pick.
And C&L is indeed a pretty amazing book.
Cheers,
Wolfgang
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RE: The Crotalus durissus-complex
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by Snakeman1982 on July 21, 2004
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Hey Dr. Wuster,
Yeah, I was surprised to see that species/subspecies get dismissed all of a sudden. I haven't been keeping track of it, can you site the publication which made that change. I guess I missed it in the literature.
I've got the Bio. of the Vipers right next to me, even though I am in Florida and suppose to be on a "vacation" trip from research and away from my books. I've skimmed over your chapter before but haven't looked into it enough yet. I'll review over it again soon. I am guessing that since you didn't seem to approve the Bothriopsis genera, you really aren't fond of the Bothrocophias genera either.
I was actually in Orlando on saturday talking to Chris Parkinson and forgot to ask him to expand a little more on his single invasion (Bering strait) chapter of that book.
The guy I am expecting to be my graduate advisor for morphological systematics mentioned to me that I need to take a look at Malhotra and Thorpe's newest article in Molecular Phylogenetics and Evolution. I figure you are a co-author but not sure. So I'll be checking that out when I get back to a University.
I am actually very interested in the systematics of endemic island species of pitvipers (i.e. Bothrops insularis, B. alcatraz, Gloydius shedaoensis).
Geographic isolationism is one factor that has helped the biological species concept to be near obsolete. For example, plants. There are two species of trees in North America and Asia (I don't know my plants very well and can't remember the genera or common name). They are like maple, birch, oak trees or something. Anyway, they are in the same genera but one is the species occidentalis and the other orientalis (or something like that). They can interbreed but don't because one is in Asia and the other in North America. So even though they can interbreed and produce viable offspring, they are considered seperate species since they are so geographically isolated and don't interbreed.
Also, many species of plants can interbreed but don't because they have different pollinating vectors, one may reproduce in early spring while the other does in late spring, some pollinate at night while others in the day, etc... And don't even get people started about species that are asexual, lol.
I am actually quite interested in seeing what will happen to Ramphotyphlops braminus in a few thousand years throughout its new distribution. I wonder if it will acquire new variations throughout its geographic range.
Defining what constitutes a species is very hard. Do you know what the progress is in the figuring out a PhyloCode or something similar? Personally I think the Linnaean system is good but there obviously needs to be some strict phylogenetic guidelines on what a species, genera, family, class, and so on is.
Well this got a little long so I'll stop,
Robert
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RE: The Crotalus durissus-complex
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by thirdangel on July 21, 2004
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Well friends, I have quite a few of the "durissus complex," and I realize that in most cases that without a street address for their origin, most people can't really tell them apart.
I have kept rattlesankes for 25 years, and I still have trouble with the South American ones. I sincerely have to question the subspecific recognition of some of these! I am still struggling with the idea that the SA and CA forms are different species (simus vs durissus). Someone needs to develope a key to these guys and I wish that L & C gave better reasons in the book for the species split -- did I miss something?
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RE: The Crotalus durissus-complex
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by Snakeman1982 on July 22, 2004
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You're very correct.
Many biologist don't care to recognize subspecies, especially for morphological reasons. Personally, I enjoy subspecies statis on many herps but I tend to be more of a splitter myself. I don't get into county ranges or anything.
I don't know enough about the durissus complex, since I have never seen one in the wild. But the Crotalus viridis/oreganus complex is another excellent example of this stuff. I have caught a heck of a lot of great basin rattlesnakes and only a couple that looked very similar to one another. Just about every individual that I ever found had different colors or slightly different patterns than I had seen previously. One day back in 2000 I crossed the snake river in Idaho and caught a nice sized rattlesnake on the bank. Then a couple of hours and two miles or so later, I caught another one on the top of the canyon on the other side of the snake river. They were only seperated by about two miles and a river but they looked completely different. Obviously still in the viridis group but different color and diamond patterns.
So, there is a lot of debate about subspecies and such.
Robert
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RE: The Crotalus durissus-complex
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by CAISSACA on July 22, 2004
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Robert,
Re your last-but-one post:
> Yeah, I was surprised to see that species/subspecies get dismissed all of a sudden. I haven't been keeping track of it, can you site the publication which made that change. I guess I missed it in the literature.
A lot of this is obviously based on Campbell & Lamar's own unpublished data. If you are writing a book like this, and you have good reason to believe that "conventional wisdom" is wrong, then I guess there is every temptation to implement your ideas in such a compendium, even though the evidence may not be published.
> I've got the Bio. of the Vipers right next to me, even though I am in Florida and suppose to be on a "vacation" trip from research and away from my books. I've skimmed over your chapter before but haven't looked into it enough yet. I'll review over it again soon. I am guessing that since you didn't seem to approve the Bothriopsis genera, you really aren't fond of the Bothrocophias genera either.
No, not very fond. The case for recognition of Bothrocophias is considerably stronger than for Bothriopsis, in that the species involved are at least basal to the rest of Bothrops. However, given the strong molecular evidence associating these forms with Bothrops, I am unconvinced that peeling off these basal species into new genera really advances anything much - as far as I am concerned, it clutters up the nomenclature, and loses sight of the wood by focusing on the trees. Whether or not one likes it will depend on whether one is interested in the wood or the trees - I'll go for the former, and remain somewhat ambivalent about Bothrocophias.
> The guy I am expecting to be my graduate advisor for morphological systematics mentioned to me that I need to take a look at Malhotra and Thorpe's newest article in Molecular Phylogenetics and Evolution. I figure you are a co-author but not sure. So I'll be checking that out when I get back to a University.
I am not a coauthor, but email me if you need a PDF.
> I am actually very interested in the systematics of endemic island species of pitvipers (i.e. Bothrops insularis, B. alcatraz, Gloydius shedaoensis).
The systematics of these is pretty clear - certainly insularis and alcatraz (like unicolor) are recent isolates that got stuck on the islands after Pleistocene sea level changes cut them off from the mainland populations, and that underwent rapid morphological evolution as a result of the very different selection pressures they faced on the islands. So, their phylogenetic position is very clear. What is more debatable is what should be done in terms of nomenclature - clearly, insularis is a totally different animal from jararaca, with different pattern, size, appearance, ecology, venom, etc., and even though it is clearly phylogenetically rooted within B. jararaca, it would be very difficult to argue that it is the same species.
On the other hand, unicolor is a lot less distinct - should we call that a species as well, or a subspecies, or just a regional morph of cumanensis? Really, the choice is totally arbitrary.
> Defining what constitutes a species is very hard. Do you know what the progress is in the figuring out a PhyloCode or something similar? Personally I think the Linnaean system is good but there obviously needs to be some strict phylogenetic guidelines on what a species, genera, family, class, and so on is.
The Phylocode won't solve these problems and is really a minoroty pursuit. Strictly speaking, the Linnean system is only really useful in that it provides the binomial system for naming species that is incredibly helpful. The other ranks are totally arbitrary as to where you draw the line. There cannot be any strict phylogenetic guidelines, because nature does not come in nice, well defined categories and where uyou have a phylogentic tree, you can put in the splits pretty much wherever you want.
Cheers,
Wolfgang
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