  Using Takahashi theorem we propose an approach to extend known families of
minimal tori in spheres. As an example, the well-known two-parametric family of
Lawson tau-surfaces including tori and Klein bottles is extended to a
three-parametric family of tori and Klein bottles minimally immersed in
spheres. Extremal spectral properties of the metrics on these surfaces are
investigated. These metrics include i) both metrics extremal for the first
non-trivial eigenvalue on the torus, i.e. the metric on the Clifford torus and
the metric on the equilateral torus and ii) the metric maximal for the first
non-trivial eigenvalue on the Klein bottle.
