Updated estimates of biotic diversity and endemism for Madagascar—revisited after 20 years

Abstract The terrestrial and marine biotypes of Madagascar are critical priorities for conservation, with almost unparalleled levels of endemism, species diversity and human threat for a land area of its size. Field inventories and molecular-based research conducted from the mid 1980s to present have greatly expanded knowledge of the country's biota, for some groups with nearly exponential growth in measures of species diversity. I provide updated measures of estimated species diversity between a book with 289 contributors, published in 2003 ( The Natural History of Madagascar ), and a full-scale update with 539 contributors, published in 2022 ( The New Natural History of Madagascar ). I compare biodiversity information presented in the new book with data from the earlier book, providing insight into scientific advancements, and revised estimates of species richness and endemism of a range of taxonomic groups.