Super Disc (early name, Super Discs, when in New York) opened for business in 1945 and was owned by Irving Feld and Viola Marsham. Changed name when the firm moved to Washington DC in 1946.
The firm made R&B, Jazz, Gospel and C&W records. Most successful Super Disc recording I know of (there may have been a popular country act, though) is "Little boy" by Rev Kelsey (an important preasher in DC), which got to 13 on the R&B chart in 1948 (for one week only, folks). Elder Lightfoot Solomon Michaux also recorded for the label.
MGM acquired the catalogue in 1948. Feld and Marsham don't appear to have been associated with any other record companies.
American Don't know much about this company. It was based in Woodside, Long Island, NY. It made pop and Jazz records. First issue was in December 1945; last in November 1952.
Arista Another one I don't know much about. It was based in Baltimore. Made Gospel and Jazz records. Apparently closed in 1947.
MG