Madagascar’s biota is hyperdiverse and includes exceptional levels of endemicity. We review the current state of knowledge on Madagascar’s past and current terrestrial and freshwater biodiversity by compiling and presenting comprehensive data on species diversity, endemism, and rates of species description and human uses, in addition to presenting an updated and simplified map of vegetation types. We report a substantial increase of records and species new to science in recent years; however, the diversity and evolution of many groups remain practically unknown (e.g., fungi and most invertebrates). Digitization efforts are increasing the resolution of species richness patterns and we highlight the crucial role of field- and collections-based research for advancing biodiversity knowledge and identifying gaps in our understanding, particularly as species richness corresponds closely to collection effort. Phylogenetic diversity patterns mirror that of species richness and endemism in most of the analyzed groups. We highlight humid forests as centers of diversity and endemism because of their role as refugia and centers of recent and rapid radiations. However, the distinct endemism of other areas, such as the grassland-woodland mosaic of the Central Highlands and the spiny forest of the southwest, is also biologically important despite lower species richness. The documented uses of Malagasy biodiversity are manifold, with much potential for the uncovering of new useful traits for food, medicine, and climate mitigation. The data presented here showcase Madagascar as a unique “living laboratory” for our understanding of evolution and the complex interactions between people and nature. The gathering and analysis of biodiversity data must continue and accelerate if we are to fully understand and safeguard this unique subset of Earth’s biodiversity.

Madagascar’s unique biota is heavily affected by human activity and is under intense threat. Here, we review the current state of knowledge on the conservation status of Madagascar’s terrestrial and freshwater biodiversity by presenting data and analyses on documented and predicted species-level conservation statuses, the most prevalent and relevant threats, ex situ collections and programs, and the coverage and comprehensiveness of protected areas. The existing terrestrial protected area network in Madagascar covers 10.4% of its land area and includes at least part of the range of the majority of described native species of vertebrates with known distributions (97.1% of freshwater fishes, amphibians, reptiles, birds, and mammals combined) and plants (67.7%). The overall figures are higher for threatened species (97.7% of threatened vertebrates and 79.6% of threatened plants occurring within at least one protected area). International Union for Conservation of Nature (IUCN) Red List assessments and Bayesian neural network analyses for plants identify overexploitation of biological resources and unsustainable agriculture as the most prominent threats to biodiversity. We highlight five opportunities for action at multiple levels to ensure that conservation and ecological restoration objectives, programs, and activities take account of complex underlying and interacting factors and produce tangible benefits for the biodiversity and people of Madagascar.

Malvales is a diverse order of flowering plants, economically and ecologically relevant, and it is known for its broad morphological variability. Recent phylogenomic studies have revealed a complex evolutionary history for the order, including localised phylogenetic discordances among nuclear loci. However, since the late 1990s, Malvales classification has largely been neglected. This study aims to address this gap by revisiting the classification of Malvales, with a focus on its largest family, Malvaceae. By integrating phylogenomic and morphological datasets, our primary goals are to provide an updated phylogeny for the order and to map key traits supporting a revised suprageneric classification, while accounting for gene and species tree conflicts. Our molecular dataset included 194 genera and 309 nuclear genes, obtained through target sequence capture using Angiosperms353 probes. This dataset covers approximately half of the known genera in the order, representing all families and subfamilies, as well as nearly all tribes, and all subtribes. A coalescent approach utilising nuclear gene trees was used to infer phylogenetic relationships. A morphological matrix with 50 characters relevant for suprageneric classification was compiled, and character‐state distributions for selected traits were mapped against the phylogenetic tree to identify and discuss diagnostic features for clades. Phylogenetic relationships and the monophyly of most groups aligned closely with previous studies. Morphological traits that define key clades varied significantly across Malvales, with differences observed in growth habit, leaf structure, pollen type, floral features, and fruit/seed morphology. In Malvaceae, we resolved uncertainties in the early Malvoideae lineages, and we describe a new tribe, Pentaplareae tr. nov., which clarifies the taxonomic placement of a previously uncertain genus. Additionally, we propose the recognition of a new subfamily, Matisioideae subfam. nov., elevated from its former status as a tribe, and positioned as the sister group to Malvoideae. This study highlights how taxonomic frameworks can be refined even in the face of conflicting phylogenomic data, demonstrating the importance of integrating molecular and morphological evidence in revising classifications.

The ecology of Madagascar's grasslands is under-investigated and the dearth of ecological understanding of how disturbance by fire and grazing shapes these grasslands stems from a perception that disturbance shaped Malagasy grasslands only after human arrival. However, worldwide, fire and grazing shape tropical grasslands over ecological and evolutionary timescales, and it is curious Madagascar should be a global anomaly. We examined the functional and community ecology of Madagascar's grasslands across 71 communities in the Central Highlands. Combining multivariate abundance models of community composition and clustering of grass functional traits, we identified distinct grass assemblages each shaped by fire or grazing. The fire-maintained assemblage is primarily composed of tall caespitose species with narrow leaves and low bulk density. By contrast, the grazer-maintained assemblage is characterized by mat-forming, high bulk density grasses with wide leaves. Within each assemblage, levels of endemism, diversity and grass ages support these as ancient assemblages. Grazer-dependent grasses can only have co-evolved with a now-extinct megafauna. Ironically, the human introduction of cattle probably introduced a megafaunal substitute facilitating modern day persistence of a grazer-maintained grass assemblage in an otherwise defaunated landscape, where these landscapes now support the livelihoods of millions of people.

Summary: This paper is the fourth part of the taxonomic revision of the genus Phyllanthus in Madagascar and the Comoro Islands. Here we treat Pseudogomphidium Ralim. & Cable sect. nov. consisting of nine species that we misplaced in the subgenus Gomphidium (Baill.) G.L.Webster in our previous paper. Two species are new to science: Phyllanthus razakamalalae Ralim. & Cable, sp. nov. and P. ankirindrensis Ralim. & Cable, sp. nov. We also treat three unplaced species: P. analamerae Leandri, P. coluteoides Müll.Arg. and P. vergens Baill. An identification key, descriptions, distribution maps and IUCN Red List assessments are provided.