A new population of Otus, allied to those species on nearby islands in the Indian Ocean, was discovered during studies in forest habitats on the island of Mohéli (Comoros). The most important differences between the species are presented in tabular form. Voice is the single most important difference between the four Comorian Otus populations. The uniqness of the taxon is supported by a number of phenotypical characteristics, the most obvious being the general coloration (rufous-brown) and the existence of a rufous phase. The species is found in dense humid forest on Mohéli, which is restricted to 3,000 ha (or 5% of the island's area), where it occurs at a density of c l bird / 5 ha in near-primary forest (1,000 ha) and 1 bird/ 10 ha in more degraded stands (2,000 ha). The total population is estimated at c 400 individuals.