Diversification in the Comoros: Review of the <i>Laccophilus alluaudi</i> Species Group with the Description of Four New Species (Coleoptera: Dytiscidae)

The Laccophilus alluaudi species group is an interesting case of an endemic species radiation of Madagascar and the Comoros. To date, a single species, Laccophilus tigrinus Guignot, 1959 (Anjouan), is known from the Comoro Islands, with eight other species known from Madagascar. Here we review the Laccophilus alluaudi species group from the Comoro Islands based on partly new material. We recognize five species, out of which four are here described as new: L. mohelicus n. sp. (Mohéli), L. denticulatus n. sp. (Grande Comore), L. michaelbalkei n. sp. (Mayotte) and L. mayottei n. sp. (Mayotte). Based on morphology of male genitalia, we hypothesize that the five species form a monophyletic group and originated from a single colonization event from Madagascar. If confirmed, this would constitute one of the few examples of intra-archipelago diversification in the Comoros. The knowledge of species limits in relation to their distribution in the Comoros archipelago is also urgently needed in the face of rapid habitat degradation