A single seed dispenser for a precision automatic sower includes a cover for seeds to be distributed joined to a body containing a cavity in communication with an aspirator of the seeds via a conduit inserted in a hole on the body, a distribution disc with holes contained in a compartment delimited by the body and by the cover; a driving disc joined through pins to the distribution disc, both discs being put into rotation by a shaft actuated by an actuator for commanding rotation of the discs; and a selector device for the seeds pivoted on the edge of the body. The selector device includes a plate which presents at least two toothed portions, having teeth of different sizes and a curved sector mounted against the surface of the distribution disc opposite to the plate and has protrusions having inclined surface facing the distribution disc.