“…Then the admitted Lie symmetry algebra is no longer infinite-dimensional and nontrivial symmetries of the original system can be retrieved [43]. This idea has been successfully applied in several instances ( [43], [57], [47], [44], [49], [35], [45], [15], [53]). Also in [39] we have shown that first integrals can be obtained by Lie group analysis even if the system under study does not come from a variational problem, i.e.…”