\begin{tikzpicture}[baseline]
    \node (S) at (0,0) [circle, draw] {$S$};
     \filldraw (S.180) circle (.5mm);
    \node (x1) at (S.135 |- -1,1){};
    \node (x2) at  (S.45 |- -1,1){} ;
    \draw (S.135) -- (x1.-90);
    \draw[rounded corners=2mm] (x1.90) -- ++(90:5mm) -- (-1,1.65)--(-1,1) -- (1,1) -- (1,1.5);
    \draw (S.90) node [above] {...};
    \draw (x2.90) -- ++(90:5mm);
    \draw (S.45) -- (x2.-90);
\end{tikzpicture}
