Museomics unveil systematics, diversity and evolution of Australian cycad-pollinating weevils

Eco-evolutionary evidence for the global diversity pattern of Cycas (Cycadaceae)

The evolution of the latitudinal diversity gradient (LDG), characterized by a peak in diversity toward the tropics, has captured significant attention in evolutionary biology and ecology. However, the inverse LDG (i-LDG) mechanism, wherein species richness increases toward the poles, remains inadequately explored. Cycads are among one of the oldest lineages of extant seed plants and have undergone extensive diversification in the tropics. Intriguingly, the extant cycad abundance exhibits an i-LDG pattern, and the underlying causes for this phenomenon remain largely elusive. Here, using 1,843 nuclear genes from a nearly complete sampling, we conducted comprehensive phylogenomic analyses to establish a robust species-level phylogeny for Cycas, the largest genus within cycads. We then reconstructed the spatial-temporal dynamics and integrated global environmental data to evaluate the roles of species ages, diversification rates, contemporary environment, and conservatism to ancestral niches in shaping the i-LDG pattern. We found Cycas experienced decreased diversification rates, coupled with the cooling temperature since its origin in the Eocene from continental Asia. Different regions have distinctively contributed to the formation of i-LDG for Cycas, with the northern hemisphere acting as evolutionary museums and the southern hemisphere serving as cradles. Moreover, water-related climate variables, specifically precipitation seasonality and potential evapotranspiration, were identified as paramount factors constraining Cycas species richness in the rainforest biome near the equator. Notably, the adherence to ancestral monsoonal climates emerges as a critical factor in sustaining the diversity pattern. This study underscores the imperative of integrating both evolutionary and ecological approaches to comprehensively unravel the mechanisms underpinning global biodiversity patterns.

New combinations and synonymies in the weevil genus Lyterius Schnherr (Coleoptera, Curculionidae), with a conspectus of historical works on Daldorffs Sumatran beetles

In preparation for a future taxonomic revision, we explore provenance, collectors, original owners and current repositories of the type material for three available genus-group names, Lyterius Schnherr, 1844, Barisoma Motschulsky, 1863 and Plaxes Pascoe, 1885, which have been applied to a group of small, relatively flat weevils associated with Pandanaceae. Lectotypes are designated for Rhynchaenus musculus Fabricius, 1802 and Plaxes impar Pascoe, 1885. The lectotype of Rh. musculus is designated as neotype for Curculio abdominalis Weber, 1801, making the species names objective synonyms (reestablished synonymy), with C. abdominalis having date priority. The names Barisoma Motschulsky and Plaxes are placed in synonymy with Lyterius (new synonymies). Five valid species names are recognised in Lyterius, L. abdominalis (Weber), L. dispar (Faust, 1896) new combination, L. impar (Pascoe) new combination, L. instabilis Boheman, 1844 and L. pandanicola (Motschulsky, 1863) new combination. We also provide an overview of the early descriptive works on Sumatran beetles collected by Daldorff and their original owners.