Uncertainties persist in the delineation of tribes and genera within the cosmopolitan and species‐rich Rhamnaceae. In this family, the identification of tribes and genera largely depends on combinations of traits rather than single synapomorphies, diagnostic morphological features being often shared among several clades. When taxonomic treatments based on morphological traits are in conflict with each other, phylogenetic reconstructions can help to guide taxonomic efforts. In this study, we present the largest molecular dataset to date for Rhamnaceae, by combining trnL‐trnF and ITS sequence data for more than 400 taxa, either newly sequenced or retrieved from GenBank. Our sampling design includes all 11 Rhamnaceae tribes and 57 genera. We used fasttree‐like searches, maximum likelihood estimates, and Bayesian analyses to generate a consensus phylogeny. Our reconstructions support most of the tribes as monophyletic, except Paliureae. Similarly, our analyses show the monophyly of most genera, with the exception of Ziziphus which appears to be paraphyletic. To preserve its monophyly, some species are excluded from Ziziphus and either attributed to the resurrected genus Sarcomphalus or to Pseudoziziphus, which is newly described here. Finally, our study highlights remaining uncertainties concerning phylogenetic relationships within Rhamnaceae, and identifies genera for which an increased sampling effort is encouraged.

Summary Despite the role of polyploidy in multiple evolutionary processes, its impact on plant diversification remains controversial. An increased polyploid frequency may facilitate speciation through shifts in ecology, morphology or both. Here we used Allium to evaluate: (1) the relationship between intraspecific polyploid frequency and species diversification rate; and (2) whether this process is associated with habitat and/or trait shifts. Using eight plastid and nuclear ribosomal markers, we built a phylogeny of 448 Allium species, representing 46% of the total. We quantified intraspecific ploidy diversity, heterogeneity in diversification rates and their relationship along the phylogeny using trait‐dependent diversification models. Finally, we evaluated the association between polyploidisation and habitat or trait shifts. We detected high ploidy diversity in Allium and a polyploidy‐related diversification rate shift with a probability of 95% in East Asia. Allium lineages with high polyploid frequencies had higher species diversification rates than those of diploids or lineages with lower polyploid frequencies. Shifts in speciation rates were strongly correlated with habitat shifts linked to particular soil conditions; 81.7% of edaphic variation could be explained by polyploidisation. Our study emphasises the role of intraspecific polyploid frequency combined with ecological drivers on Allium diversification, which may explain plant radiations more generally.

Aim:We investigated whether the fossil-rich and cosmopolitan buckthorn family (Rhamnaceae, dating back to the Cretaceous) was influenced by vicariance events following the Gondwanan breakup. To answer this question, we focused on the ziziphoid lineage of the buckthorn family, because extant ziziphoid taxa comprise tribes and genera exclusively or at least predominantly distributed in the Southern Hemisphere (Australia, Africa, and South America).Location: World-wide. Methods:We generated a DNA alignment of 26,989 bp (from plastid, mitochondrial, and nuclear genomes), comprising 575 taxa of Rhamnaceae and related families, including all major lineages within Rhamnaceae and closely related families. We used nine internal fossils to set constraints in our molecular dating analyses. We used 'BioGeoBEARS' in R to reconstruct ancestral areas in order to infer the impact of vicariance events on the ziziphoids caused by Gondwanan fragmentation. Results:Our biogeographic analyses illustrate that the ziziphoid lineage was influenced by both long-distance dispersal and Gondwanan breakup vicariance events.Yet, these vicariance events cannot explain all divergence events at the backbone of this lineage. Main conclusions:Our study highlights that a taxon's distribution throughout the Northern Hemisphere can be the result of vicariance, but this process may be obliterated by more recent long-distance dispersal (LDD). Our study also highlights that sufficiently old taxa may sometimes constitute better models to investigate the impact of Gondwanan-driven vicariance than taxa with a current disjunct distribution in the Southern Hemisphere. K E Y W O R D S

A plethora of studies investigating the origin and evolution of diverse mountain taxa has assumed a causal link between geological processes (orogenesis) and a biological response (diversification). Yet, a substantial delay (up to 30 Myr) between the start of orogenesis and diversification is often observed. Evolutionary biologists should therefore identify alternative drivers of diversification and maintenance of biodiversity in mountain systems. Using phylogenetic, biogeographic, and diversification rate analyses, we could identify two independent processes that most likely explain the diversity of the widespread genus Allium in the Qinghai–Tibet Plateau (QTP) region: (1) While the QTP-related taxa of the subgenus Melanocrommyum diversified in situ, (2) QTP-related taxa of other subgenera migrated into the QTP from multiple source areas. Furthermore, shifts in diversification rates within Allium could not be attributed spatially and temporally to the uplift history of the QTP region. Instead, global cooling and climate oscillations in the Quaternary were major contributors to increased speciation rates in three clades of Allium. Our study therefore adds to the growing evidence supporting the “mountain-geo-biodiversity hypothesis”, which highlights the role of climate oscillations for the diversification of mountain organisms.

We describe the frog species Diasporus citrinobapheus sp. n. from the Cordillera Central of western Panama. The new species differs from all other species in its genus in coloration, disk cover and disk pad shape, skin texture, advertisement call, and size. It is most similar to Diasporus tigrillo, from which it differs in dorsal skin texture, relative tibia length, number of vomerine teeth, ventral coloration, dorsal markings, and relative tympanum size, and to Diasporus gularis, from which it can be distinguished by the lack of membranes between the toes, adult size, posterior thigh coloration, and position of the choanae. We provide data on morpho- logy, vocalization, and distribution of the new species, as well as brief information on its natural history.