F♯m over C (minor triad over major triad a tritone apart).
C           E        G     A           C♯             F♯    
1           3        5     6           ♭9             ♯11         

Parent scales are B♭ diminished (no 1 or 4) or C♯ diminished (no 2 or 6) or E diminished (no 4 or 7) or G diminished (no ♭3 or ♯5).
C  C♯       E     F♯ G     A
1  ♭2       3     ♯4 5     6

Related chords (reverse diminished).
| A13♯9 (no ♯9 or ♯4) | C7♭9♯11 (no ♯9 or ♭7) | E♭13♯9 (no 1 or 5) | F♯7♭9♯11 (no 3 or 6) |