There really is no main species of molurus. Indians are the nominate form as P. molurus molurus only because they were the first of the subspecies to be described and named. They are not as well known in captivity due to your observation that they have been listed under endangered species status since 1973. They are intermediate in size between burmese pythons and P. molurus from Sri Lanka (formerly Ceylon), with a maximum recorded size of about 19 feet. Full grown adult indian females probably average 12 to 15 feet, with adult males being smaller. They appear to grow slightly slower than burmese, and probably average a better disposition than most Sri Lanka molurus. However, there are Sri Lanka specimens that are quite calm, as the young adult female I am holding in the picture below illustrates.
Kelly
