Hi David,
I am not sure if Sigma made any lenses in the Leica R series lenses. I do not believe so, but I may be incorrect. In fact, Sigma got there wrists slapped for producing their own lenses in the Leica R mount without permission. The only independant lens maker from Japan that I am aware of to be given permission for making their own lenses in a Leica R mount was Tamron. Besides Leica, Minolta, Schneider, Zeiss, Kyocera, and Angeneau made lenses in the Leica R series, but all of these lenses were made to Leica specs and tolerances to within as I understand it 1/6 of a stop (the equivalent Minolta lens as an example was to within 1/3 stop). Minolta made the 800mm Mirror Leica as well as many of the zoom lenses including the f4.0 70-210mm (1 touch- I have a fine performing version), and I believe some of the 35mm-70mm. Angeneau made several of the earlier Leica zoom lenses. Schneider made the 21mm f3.4 (not for usage with the R3-R7, R8 & R9 ????) and 21mm f4.0 Super Angulons in the R line as well as the 21mm Super Angulon in the M line as well as the 2 Leica R PC lenses. Zeiss made the 15mm lens in the R series. Kyocera has made at least some of the later zooms in the series including the f4 80-200mm (as I recall) 2 touch that replaced the 70-210mm (1 touch).
Rich