Diversity and distribution of the family Asteraceae in Mexico

Background: In Mexico, the family Asteraceae (or Compositae) has attracted the attention of prominent botanists in the last decades; for this reason, it has a long tradition of investigation of its floristic richness. The family has a large bibliographic collection that allows to synthesize and update its floristic knowledge. Question: Which is the current richness of Asteraceae in Mexico? How Asteraceae is distributed throughout this country? Which genera or regions require more detailed studies to improve our knowledge of the family in the country? Study site: Mexico. Methods: An exhaustive review of floristic and taxonomic literature was carried out, as well as the revision of about 200,000 herbarium specimens deposited in more than 20 herbaria both nationally and abroad. Results: Mexico currently records 26 tribes, 417 genera and 3,113 species of Asteraceae, of which 3,050 are native species and 1,988 (63.9 %) endemic to this country. The most important genera, both for the number of species and for their endemic component, are Ageratina (164 and 135, respectively), Verbesina (164, 138) and Stevia (116, 95). The states with the greatest number of species are Oaxaca (1,040), Jalisco (956), Durango (909), Guerrero (855) and Michoacan (837), while the biomes with the greatest richness are the temperate forest (1,906) and the xerophytic scrub (1,254). Only 31 genera do not have taxonomic revision or enough information to carry out the correct determination of their species, although for many others it is necessary to update the taxonomic information by the new discoveries or the taxonomic changes at species level. The collection effort throughout the country reveals that there are still important regions that require exploration to better document their species richness. Conclusions: The evaluation of the literature and the review of herbarium specimens shows an optimistic scenario regarding the knowledge of the family in Mexico. However, there are still large areas of the territory that once properly explored, will modify the figures here discussed about their Asteraceae richness.