In this paper, we address the definition of a low-complexity subgroup formation algorithm for multicast data delivery in Long Term Evolution (LTE) networks. With this aim, we extend the subgroup merging scheme (SMS), designed for generic Orthogonal Frequency Division Multiple Access (OFDMA) systems, by proposing two low-complexity subgroup formation schemes, named L-SMS and L-eSMS. Such schemes are tailored to exploit the great potentialities of LTE systems. Specifically, L-SMS is proposed in order to improve the scalability of SMS by handling a more efficient subgroup formation scheme with a computational cost which does not depend on the multicast group size. The L-eSMS also improves the resource assignment phase with the aim to achieve better near-optimal performance compared to L-SMS. Through simulations, we evaluated the effectiveness of the proposed schemes in different cell deployment and multicast configuration scenarios. The achieved results underlined that the proposed L-eSMS is well designed in order to guarantee performance close to the optimal one.