There isn't.
There are 4 types of spinners.
Right Handed
Off Spinners, eg. Saqlain Mushtaq, Murali
Leg Spinners, eg. Shane Warne, Stuart McGill
Left Handed
Slow Left Arm Orthodox, eg. Daniel Vettori, Phil Tufnell
Slow Left Arm Chinaman, eg. Brad Hogg, Me.
You are making an easy mistake. A Slow Left Arm Orthodox bowler does use the same grip and hand action as an off-spinner, but he cannot possibly be an off-spinner as he turns the ball in the other direction.