Given a semistable non isotrivial fibration f : X → P 1 with general non hyperelliptic fiber of genus g ≥ 4, we show that if the number s of singular fibers is 5, then the genus is ≤ 11, thus improving the previously known bound g ≤ 17. Furthermore we show that for each possible genus the general fiber has gonality at most 5 and we describe the corresponding fibrations as the resolution of concrete pencils of curves on minimal rational surfaces.
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