Cnidoscolus (Euphorbiaceae) is an American genus of 99 species, distributed from the United States to Argentina and the Antilles. The genus is noteworthy due to the presence of stinging hairs, a feature otherwise very rare in Euphorbiaceae. Here we constructed a phylogenetic hypothesis for relationships in Cnidoscolus using both nuclear (ITS) and chloroplast (psbA-trnH, trnL-trnF) markers. We included 44 species and 7 additional subspecies (of 4 species), which represent a broad geographic and taxonomic sample of the genus. The nuclear and chloroplast datasets were analyzed separately. Various incongruencies were detected between the nuclear and plastid phylogenies, and in general, the ITS reconstruction is better resolved and has more clades that are highly supported. In both analyses, Cnidoscolus is confirmed to be monophyletic and composed of two major lineages: a northern clade that comprises species distributed primarily in North and Central America and a southern clade composed of mostly South American species. We conducted ancestral reconstructions of three characters important in the classification of the genus: (1) primary leaf venation, (2) number of staminal whorls in the androecium, and (3) petiolar glands. Based on morphology and the molecular phylogeny, we propose an updated infrageneric classification that recognizes eight sections and two subsections, and we place 98 of the accepted species into this new classification, with one species' position uncertain.

The shortage of reliable primary taxonomic data limits the description of biological taxa and the understanding of biodiversity patterns and processes, complicating biogeographical, ecological, and evolutionary studies. This deficit creates a significant taxonomic impediment to biodiversity research and conservation planning. The taxonomic impediment and the biodiversity crisis are widely recognized, highlighting the urgent need for reliable taxonomic data. Over the past decade, numerous countries worldwide have devoted considerable effort to Target 1 of the Global Strategy for Plant Conservation (GSPC), which called for the preparation of a working list of all known plant species by 2010 and an online world Flora by 2020. Brazil is a megadiverse country, home to more of the world's known plant species than any other country. Despite that, Flora Brasiliensis, concluded in 1906, was the last comprehensive treatment of the Brazilian flora. The lack of accurate estimates of the number of species of algae, fungi, and plants occurring in Brazil contributes to the prevailing taxonomic impediment and delays progress towards the GSPC targets. Over the past 12 years, a legion of taxonomists motivated to meet Target 1 of the GSPC, worked together to gather and integrate knowledge on the algal, plant, and fungal diversity of Brazil. Overall, a team of about 980 taxonomists joined efforts in a highly collaborative project that used cybertaxonomy to prepare an updated Flora of Brazil, showing the power of scientific collaboration to reach ambitious goals. This paper presents an overview of the Brazilian Flora 2020 and provides taxonomic and spatial updates on the algae, fungi, and plants found in one of the world's most biodiverse countries. We further identify collection gaps and summarize future goals that extend beyond 2020. Our results show that Brazil is home to 46,975 native species of algae, fungi, and plants, of which 19,669 are endemic to the country. The data compiled to date suggests that the Atlantic Rainforest might be the most diverse Brazilian domain for all plant groups except gymnosperms, which are most diverse in the Amazon. However, scientific knowledge of Brazilian diversity is still unequally distributed, with the Atlantic Rainforest and the Cerrado being the most intensively sampled and studied biomes in the country. In times of “scientific reductionism”, with botanical and mycological sciences suffering pervasive depreciation in recent decades, the first online Flora of Brazil 2020 significantly enhanced the quality and quantity of taxonomic data available for algae, fungi, and plants from Brazil. This project also made all the information freely available online, providing a firm foundation for future research and for the management, conservation, and sustainable use of the Brazilian funga and flora.

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