Reptile & Amphibian Forums

Theory,
Since no one seems to have locality data on unicolor I am going to post this in an effort to get someone to share what they know or at least have a starting point to understand where to look. My theory is that there is a pure Unicolor population in Nicaragua. It seems to me that pure specimens have come from parts of Costa Rica which borders Nicaragua. It also appears that there are intergrade specimens that come from both sides of Nicaragua. It also appears that the farther you get away from Nicaragua you have pure blacktailed specimens, on both sides, Venezuela and Guatemala. It makes sense that if unicolor is at the very center of the range for Drymarchon that this is where they may have got their start. The far extremes of their range can both produce jet black animals. Yes I have been told there is jet black yellowtail. There are black yellow tailed animals from Guyana. I am hoping at this point to have someone who has done some work on the subject to get in my face since I do not have any answers just theory. Fact, how can anyone claim to have pure specimens if there is no locality data.

Drymarchon species got their start in the center of their range. Hence Yellowtail at one end Indigo at the other end as far as extremes of the range.

it seems like the more we learn about the tropical drys, we realize how little is actually known about them. all i [think] i know is that uni's are somewhat of an upland animal on the pacific side of central america & that bt's are more prevalent on the caribbean side. chris harrison once posted a range map here for all the known subs but i cannot seem to find it. perhaps someone can however & will re-post it.......

Map

Awsome, if this map is accurate it should be on the Indigo webpage. Saves alot of poking around.

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hey, thanks for posting that map. It's got more local detail than the only published range I know of. But what about the occurrence of melanurus within the range of c. corais ?

I believe this map was posted one maybe two years ago. Believe it is the handy work of Chris H. I do know that Chris does his home work. You may want to address your question to him.

Dann….

So far the map fits the data I have collected except for one record found on a site called "Herpetology of Bolivia" where there is a picture of a screamer Yellowtail. Although the map does not show that far down it has me puzzled. A trip to Bolivia would be fun but there is something about runing into a drug traficer in the middle of the jungle that takes the wind out of your sails.

Your right that entire region is not to be taken lightly by the innocent snake hunter.
Not to mention the parasites dwelling in those jungles.

Dann

As I mentioned in an earlier post, I have a working hunch that the unicolor/melanurus distinctions may not hold up well with a detailed study of specimens from across Middle America. That's based on a a range of museum specimens from known localties; am hoping to look into this more when I have time in '06. As for Drymarchon evolution and radiation beginning at the center of their overall range; that's certainly a good working theory. There may be a tendency (with many exceptions...) for a species group to have melanistic forms at the northern and southern latitudes.

Speaking of distinctions between BT and unicolor cribos, do you know what exactly it is that distinguishes the two besides color and size? Are there any big scalation or structural differences? What makes a unicolor or blacktail besides the color?
There's been a lot of heated discussion on this topic as of late. I've personally seen quite a few WC animals that would be considered "intergrades," but it almost seems like there's more of them out there than there are "pure" specimens of either variety.
Robert

Pure vs High contrast. Pure in my opinion is sometiong from the wild. You are right in that most imports are pure intergrade.LOL Chris Radon has bred Black Tailed specimens that are Jet Black on buttercream yellow (high contarst) pure? I do not have locality information on their locality but they look like what I would expect to see in a blacktail.

I know, I have one of Chris' babies from last year. She's a real beauty. My male (from a different source), on the other hand, started out with a black tail that has since faded to gray. Still a beautiful creature, but probably not suited to be her mate. They are definitely different in appearance, but I'm just not sure whether to chalk the differences up to different subspecies, geography, etc.
Robert

Here's a picture I took of Mojo tonight that shows how much his tail coloration has faded in the last 6.5 months.

That is one of the nicest animals I have seen uni or not.