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

Johannes Bergsten,Olof Biström

doi:10.3390/d14020081

Abstract

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.

Highlights

Volcanic oceanic island archipelagos, such as the Galapagos, Hawaii and the Canaries, have long fascinated biologists [1,2,3,4,5]
Based on morphological examination of material from each of the four main islands of the Comoros archipelago, it became clear that each island has at least one endemic species; we found no evidence of any species in common
L. tigrinus was described by Guignot based on material from both Anjouan and Mohéli [34]

Summary

Introduction

Volcanic oceanic island archipelagos, such as the Galapagos, Hawaii and the Canaries, have long fascinated biologists [1,2,3,4,5]. For terrestrial and freshwater organisms, a large expanse of sea constitutes a dispersal barrier. This barrier is a semipermeable filter that has reduced, but over time allowed, arrivals at frequencies dependent on extrinsic factors, such as distance to mainland, ocean currents, trade winds and island size, and intrinsic factors such as dispersal capacity, body size, salinity tolerance and the ability to withstand restricted access to food and water for long periods [2,7]. On especially large and/or more heterogenous islands, or island archipelagos, further in situ or intraarchipelago speciation may occur [8]

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