Recent diversification of Aneuraceae, an ancient family of simple thalloid liverworts

Aneuraceae, the largest family of simple thalloid liverworts, is recognised for its unique ecology and cryptic diversity despite its simple morphological features. In the present study, we explored the evolutionary history and diversification of Aneuraceae, focusing on the effects of fossil calibrations on divergence time estimates and the significance of including cryptic species in macroevolutionary analyses. We used publicly available nucleotide sequences to reconstruct chronograms of Aneuraceae, incorporating other representatives from subclass Metzgeriidae as outgroups. We also assessed the effects of various calibration approaches on chronogram reconstruction. The resulting time-calibrated phylogeny was subjected to time plots, γ-statistics, and Bayesian analysis of macroevolutionary mixtures (BAMM) to uncover diversification dynamics within the Aneuraceae lineage. Aneuraceae originated and diversified from the Upper Devonian (358.04 Mya, 95% highest posterior density: 513.61–268.36) to the Lower Carboniferous period. Our analysis revealed late bursts of diversification, with significant rate shifts at the crown node of the genus <i>Riccardia</i> and at the Neotropical clade within <i>Riccardia</i>. Including cryptic taxa in the analyses introduced an additional rate shift at the crown node of the genus <i>Aneura</i>. Aneuraceae probably originated during the middle Paleozoic, like other early terrestrial plants, although different fossil-calibration approaches significantly influenced the divergence time estimates. The speciation rate shifts in <i>Riccardia</i> could be attributed to asexual reproduction within this genus, as well as climate changes and geological events in the Neotropics. Ecological conditions at the origin of Aneuraceae may have played a role in driving its increased diversification.