{ \newcommand{\nodea}{\node[draw,circle] (a) {$I$}
%;}\newcommand{\nodeb}{\node (b) {$\ell_1$}
%;}\newcommand{\nodebc}{\node (bc) {$\ldots$}
%;}\newcommand{\nodec}{\node (c) {$\ell_g$}
%;}\newcommand{\noded}{\node (d) {$\bigstar$}
;}\newcommand{\nodee}{\node (e) {$r_1$}
;}\newcommand{\nodeef}{\node (ef) {$\ldots$}
;}\newcommand{\nodef}{\node (f) {$r_d$}
;}\begin{tikzpicture}[auto]
\matrix[column sep=.3cm, row sep=.3cm,ampersand replacement=\&]{
 \nodea  \&         \&         \&         \\ 
          \& \nodee \& \nodeef \& \nodef  \\
};

\path[ultra thick, red] (a) edge (e) edge (f);

\end{tikzpicture}}