Starting from quaternionic N=8 supersymmetric mechanics we perform a
reduction over a bosonic radial variable, ending up with a nonlinear off-shell
supermultiplet with three bosonic end eight fermionic physical degrees of
freedom. The geometry of the bosonic sector of the most general sigma-model
type action is described by an arbitrary function obeying the three dimensional
Laplace equation on the sphere S^3. Among the bosonic components of this new
supermultiplet there is a constant which gives rise to potential terms. After
dualization of this constant one may come back to the supermultiplet with four
physical bosons. However, this new supermultiplet is highly nonlinear. The
geometry of the corresponding sigma-model action is briefly discussed.Comment: 9 pages, LaTeX file, PACS: 11.30.Pb, 03.65.-