Abstract DNA barcoding helps to identify species, especially when identification is based on parts of organisms or life stages such as seeds, pollen, wood, roots or juveniles. However, the implementation of this approach strongly depends on the existence of complete reference libraries of DNA sequences. If such a library is incomplete, DNA-based identification will be inefficient. Here, we assess if DNA barcoding can already be implemented in species-rich tropical regions. We focus on the tree flora of São Paulo state, Brazil, which contains more than 2000 tree species. Using new DNA sequence data and carefully assembled GenBank accessions, we assembled 12,113 sequences from ten different regions. The ITS, rbcL, psbA-trnH, matK and trnL regions were better represented within the available sequences for São Paulo tree flora. Currently, only 58% of the São Paulo tree flora currently have at least one barcoding sequence available. However, these species represent on average 89% of the trees in São Paulo state forests. Therefore, conservation-oriented and ecological studies can already benefit from DNA barcoding to obtain more accurate species identifications. We present which taxa remain underrepresented for the São Paulo tree flora and discuss the implications of this result for other species-rich tropical regions.

Resumo: O Parque Estadual de Ilhabela - PEIb (23º 46' e 28" de latitude sul e 45º 21' 20" de latitude oeste) é responsável pela conservação de um dos mais importantes e devastados fragmentos de Mata Atlântica insular. Como forma de listar as espécies arbóreas nas trilhas da Unidade de Conservação e fornecer um instrumento prático para auxiliar no reconhecimento dessas espécies, objetivamos nesse trabalho realizar um levantamento florístico e fotográfico com distintas formas de vida para elaborar uma chave de identificação das espécies de Dicotiledôneas arbóreas com base em caracteres vegetativos. Listamos 123 espécies, presentes em 99 gêneros e 46 famílias botânicas. As famílias mais bem representadas foram Rubiaceae (15 spp.), Fabaceae (10), Piperaceae (10), Myrtaceae (8), Melatomataceae (7) e Lauraceae (7). Encontramos três espécies ameaçadas de extinção, duas novas ocorrências para o estado de São Paulo e uma nova espécie de planta para a ciência, demonstrando a importância florística do local. Elaboramos três chaves dicotômicas vegetativas de identificação sendo elas: para espécies com folhas compostas; folhas simples e opostas; e folhas simples e alternas. As chaves apresentando 97 espécies arbóreas, distribuídas em 37 famílias, baseadas em caracteres vegetativos tais como filotaxia, composição e formato do limbo, presença ou ausência de estípulas, exsudado, lenticelas, indumento, glândulas e pontuações. Nós também elaboramos pranchas fotográficas como um material suplementar de auxílio à utilização da chave de identificação.

Abstract: The Ilhabela State Park (PEIb, for Parque Estadual Ilhabela in Portuguese)-located between 23º 46' 28" south latitude and 45º 21' 20" west latitude-is responsible for the conservation of one of the most important, and most devastated, fragments of insular Atlantic Forest. To catalog the arboreal species along the trails of the Conservation Unit, and to provide a practical instrument to facilitate the recognition of these species, we aimed with this work to conduct a floristic and photographic survey of distinct life forms and create an identification key for arboreal dicotyledonous species based on vegetative characters. We cataloged 123 species belonging to 99 genera and 46 botanical families. The best-represented families were Rubiaceae (15 spp.), Fabaceae (10), Piperaceae (10), Myrtaceae (8), Melatomataceae (7) and Lauraceae (7). We found three species threatened with extinction, two new occurrences for the state of São Paulo, and one plant species new to science, demonstrating the floristic importance of the region. We developed three vegetative dichotomous identification keys: to species with compound leaves; simple and opposite leaves; and alternate simple leaves. The dichotomous keys presents 97 arboreal species, distributed among 37 families, and was based on vegetative characters such as phyllotaxis, composition and shape of the limbus, presence or absence of stipules, exudate, lenticels, indument, glands and dots. We also elaborated a photographic board with 118 species as a supplementary material to support the use of the identification key.