Current knowledge on the diversity of Eumolpinae (Coleoptera, Chrysomelidae) in New Caledonia

The Eumolpinae leaf beetles of New Caledonia are very diverse, but our knowledge about their diversity is still incomplete. Following a renewed interest in the group in the last two decades, there has been an exponential increase in the number of species described, with species descriptions and taxonomic reassessment ongoing. In this work, the catalogue of New Caledonian Eumolpinae is updated, incorporating all these recent changes, and also indicating the collection where type specimens are currently available. The updated catalogue includes 120 species in 13 genera, and more additions and taxonomic changes, including new combinations, are expected in forthcoming years. Here two new synonymies are reported, namely Dumbeastriata Jolivet, Verma & Mille, 2007 = Taophilacancellata Samuelson, 2010, syn. nov.; and Dematochromatheryi Jolivet, Verma & Mille, 2010 = Dematochromapoyensis Jolivet, Verma & Mille, 2010, syn. nov. Moreover, two species still retaining their original adscription to the genus Colaspis Fabricius, 1801, are treated as incertae sedis. This catalogue represents a useful tool for future taxonomic studies of New Caledonian Chrysomelidae and can assist biodiversity surveys and conservation studies within the archipelago.

Analysis of intrinsic evolutionary factors leading to microendemic distributions in New Caledonian leaf beetles

Microendemicity, or the condition of some species having local ranges, is a relatively common pattern in nature. However, the factors that lead to this pattern are still largely unknown. Most studies addressing this issue tend to focus on extrinsic factors associated with microendemic distributions, such as environmental conditions, hypothesising a posteriori about underlying potential speciation mechanisms, linked or not to these conditions. Here, we use a multi-faceted approach mostly focusing on intrinsic factors instead, namely diversification dynamics and speciation modes in two endemic sibling genera of leaf beetles with microendemic distributions, Taophila and Tricholapita, in a microendemicity hotspot, New Caledonia. Results suggest that the diversification rate in this lineage slowed down through most of the Neogene and consistently with a protracted speciation model possibly combined with several ecological and environmental factors potentially adding rate-slowing effects through time. In turn, species accumulated following successive allopatric speciation cycles, possibly powered by marked geological and climatic changes in the region in the last 25 million years, with daughter species ranges uncorrelated with the time of speciation. In this case, microendemicity seems to reflect a mature state for the system, rather than a temporary condition for recent species, as suggested for many microendemic organisms.

Climatic Niche, Altitudinal Distribution, and Vegetation Type Preference of the Flea Beetle Genus Arsipoda in New Caledonia (Coleoptera Chrysomelidae)

New Caledonia is one of the major biodiversity hotspots. The flea beetle genus Arsipoda (Coleoptera Chrysomelidae) is present with 21 species, all endemic. We investigated, using GIS analyses and ecological niche models, the habitat preferences of these species in terms of vegetation types, altitude, and climate, and assessed the adequacy of knowledge on the spatial parameters affecting the distribution of the genus in New Caledonia. Altitude and geology seem to play an important role in shaping species distribution. Volcanic substrate allows the growth of ultramafic vegetation, which includes most of their host plants. From a biogeographic and conservation perspective, our results report a deep link between Arsipoda species and their habitats, making them particularly sensitive to environmental modifications.