As stated in Etienne & Alonso (2005) this equation is the generalization of the dispersal-limited binomial distribution, given in eqn 24. Because the multinomial distribution is the generalization of the binomial distribution, consistency in terminology therefore requires that eqn 25 should be called the dispersal-limited multinomial distribution. Consistency in the mathematical generalization of eqn 24 then requires that Ii in the original eqn 25 must be replaced by I.
In addition, a typographic error occured in eqn 13. This equation should have ni! in the denominator instead of ni. In the online appendix A to Etienne & Alonso (2005), where eqn 13 is derived, the correct form is given.