A new pollination system in non-cleistogamous species of Viola results from nyctinastic (night-closing) petal movements – A mixed outcrossing-selfing strategy

•Discovery of a new pollination systems not described elsewhere in the genus Viola.•Temporal flower closure (nyctinasty) provides self- and cross-pollination realized by a single flower.•The timing of nyctinastic movements is correlated with stigma receptivity.•Floral characters indicate that V. banksii may have a pollination deceit strategy.•Temporal flower closure seems to be endogenous but affected by changes from light to darkness.