Third gender

[Hartmut Buescher]

>... studies of non-standard sexualities in ancient India (..., transsexualism, ... etc.)

Not least also in view of the significance of this issue in the MBh,
Robert P. Goldman's 
”Transsexualism, Gender, and Anxiety in Traditional India”
[in: Journal of the American Oriental Society 113.3 (1993): 374-401],
providing a survey of ”a number of salient examples of transsexualism
drawn from the religious and mythological texts of ancient and medieval 
India” (further references in his bibliography), is likewise rather indispensible.

HB