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[xFenrir]

Red Tail Boas are classified as follows:

Boa Constrictor Constrictor (BCC)- These are the "true red tails." These are generally the largest in size and maintain their red tails into adulthood. The tail will normally have a distinct red color that ranges from bright red to a deeper, more blood red color. They come from:
Peru
Brazil
Venezuela
Suriname
Guyana

Boa Constrictor Imperator (BCI)- This is the largest group of boa constrictors. Their tail color normally ranges from a darker, more subdued red to a more common brown color. They include the boas from Central America:
Colombia
Panama
Costa Rica
Nicaraqua
Mexico: Tamaulipas, Tarahumara
and the insular islands:
Hogg Island
Caulker Cay
Crawl Cay
Corn Island

Boa Constrictor Amarali (BCA)- Bolivian boa constrictors

Boa Constrictor Longicauda (BCL)- These come from the Tumbes region of Peru. They are also known as the Peruvian Long-tail Boa, as they have a higher scale count from their vent to tail tip, than the Peruvian BCC.

Boa Constrictor Occidentalis (BCO)- Argentine boa constrictors.

Boa Constrictor Sabogae (BCS)- Pearl Island boa constrictors

As well as, some of the lesser known sub-species:

Boa Constrictor Nebulosa- Dominican Republic, Lesser Antilles
Boa Constrictor Orophias- St. Lucia
Boa Constrictor Melanogaster- Ecuador Black Belly

It is best to research each of these, as they have different sizes, colorings, and growth rates. Here are a few websites to help you get started, where the different sub-species of Boa Constrictor are discussed and described:

http://www.boa-constrictors.com/com/com.html

http://www.cuttingedgeherp.com/contactinformation/

http://www.riobravoreptiles.com/index.htm

Physical Differences:

-Saddle Shape: Generally the BCI saddles will have a rounder apearance, looking something like this: ( ) ( ) ( ), whereas the BCC saddles generally have an apex in the saddles, much like this: } { } { } { } . While this is a good marker, it is not always reliable.

-Head Shape: The head shape between BCC and BCI may be hard to detect in neonates, but from about 1 year in age, the differences become more apparent. The BCC generally have less pronounced jaw muscles, giving the head a more slender, longer, or uniformly tapered appearance, with a more pointed shaped nose. Also, the size of the head will appear larger in relation to the size of the body in the neck area. The BCI generally has more pronounced jaw muscles and a more blunt or broader looking nose, giving the head a shorter appearance. Also the BCI head will appear smaller in relation to the size of the body in the neck area.

-Scale Count: Scale count is another indicator of Boa type, however, since alot of the numbers overlap, it should not be relied on solely. Scale count + Head shape is the most accurate method of determining the type of Boa that you have. If you are looking for a specific locale of BCC or BCI, the easiest way to ensure that you are getting what you want is to buy from a reputable breeder who will guarantee the genetics.
Here is a chart that was posted on another forum with some basic scale and saddle counts. I left the authors name in the post so that he can recieve credit:

Here are the scale counts for you.

BCC
scale counts - 75 to 95 dorsal rows.
227 to 250 ventrals.
49 to 62 subcaudals.
Average 15 to 21 saddles.

BCI
scale counts - 56 to 79 dorsal rows.
225 to 253 ventrals.
47 to 65 subcaudals.
Average 22 to 30 saddles.

BCA ( Amaral Boa)
scale counts - 71 to 79 dorsal rows.
226 to 237 ventrals.
43 to 52 subcaudals.
Average 22 saddles.

BCL (Longicauada)
scale counts - 60 to 76 dorsal rows.
243 to 247 ventrals.
50 to 67 subcaudals.
Average 19 to 21 saddles.

BCO (Occidentalis)
scale counts - 65 to 87 dorsal rows.
242 to 251 ventrals.
45 subcaudals.
Average 22 to 30 saddles.



For those who are doing research or looking for care info, the following links are to the different sections of "The Ultimate Boa Constrictor Care Guide" by Clay English:

http://www.redtailboas.com/f110/part...ew-line-40589/
http://www.redtailboas.com/f110/part...-online-40590/
http://www.redtailboas.com/f110/part...-online-40591/
http://www.redtailboas.com/f110/emer...-online-40594/
http://www.redtailboas.com/f110/feed...ew-line-40593/
http://www.redtailboas.com/f110/inst...-online-40592/

You can also download the entire guide in PDF format free by going to this link and registering:

http://www.redtailboas.com/f110/down...ion-3-a-31312/

Also, here is a fairly in-depth article by Gus Rentfro, Rio Bravo Reptiles, on Boa Constrictor care:

http://www.redtailboa.net/forums/sna...tail-boas.html

Hopefully, all of these links and info will help those doing research, or the keeper who is just looking for some additional resources and info...

-Vypyrz-