The chart is not entirely accurate. It is "Reform" Judaism, not "Reformed," and the Samaritans of today are descended not from the Sadducees (sort of the Jewish establishment at the time of Christ) but from the Samaritans of that period, who in turn seem to be descended mostly from the 10 northern tribes (maybe some non-Israelite mixture from people settled there by the Assyrians).
A lot of male Jews whose families have a tradition of having been priests have very similar Y-DNA which suggests a common ancestor around 1300 before our era--in other words, about the time of Aaron.
The Samaritans are not depicted as descending from Sadduccees. The green line goes behind the Sadduccees box not through it.
Samaritans are a first temple sect of Hebraic religion.