In this note we give a short survey on joint work with K. Behnke; details will appear in [1] and [2].Let n, q be positive integers with 2 < q < n and gcd(«, q) = l, m = n -q. We define elements 0 W , \jj , r\ E. GL( G n has finite order Amq\ G +1 is the binary dihedral group of order 4g. G w acts on C 2 in the usual way; the quotient C 2 /G n has precisely one (normal) complex-analytic singularity. We call it the dihedral singularity of type D n . If we expand n/q into the modified continued fraction à la HirzebruchJung,