Mezilaurus revolutifolia (Lauraceae), a new species from Brazilian Atlantic Forest F. M. Alves 1 , V. C. Souza 1 & P. L. R. de Moraes 2 Summary. A new species of Lauraceae, Mezilaurus revolutifolia F. M. Alves & P. L. R. Moraes from eastern Bahia, Brazil, is described and illustrated. This is the second species of the genus known to be endemic to the Brazilian Atlantic forest as previously only M. navalium (Allemão) Taub. ex Mez was known from this region. M. revolutifolia is distinguished from all other species of the genus by its revolute and glabrous leaves and glabrous racemose inflorescences with glabrous flowers clustered at the tips of the lateral branches. Key Words. Bahia, taxonomy. Introduction Mezilaurus Taub. comprises about 20 species of trees and shrubs, known from Colombia, Ecuador, Peru, Bolivia, Venezuela and Guyana to central-western and southeastern Brazil. The majority of species are found in the Amazon, a few occur in the forest of the Brazilian Atlantic coast, neotropical semi-decid- uous seasonal forest and in the Brazilian savanna (Cerrado). Mezilaurus can be recognised by its rhythmic growth of branches, leaves clustered at the tips of the branches, bisexual flowers with 3 fertile stamens representing the third androecial whorl, 2-locular anthers and fruit with a minute discoid cupule. Besides Mezilaurus, Licaria Aubl., Mocinnodaphne Lorea-Hern. and two Aiouea Aubl. species have flowers with bisexual flowers, three fertile 2-locular stamens and occur in the Neotropics. However Licaria has lax leaves on the branches and fruit with a double rimmed cupule of variable size and shape (Kurz 1982). The species of Aiouea have lax leaves on the branches, fertile stamens representing the first androecial whorl and grow a large cupule (Kubitzki & Renner 1982). On the other hand, Mocinnodaphne has triplinerved and lax leaves on the branches and fruit with a more developed cupule (Lorea-Hernández 1995). Phylogenetically, Mezilaurus has a close relation- ship with Williamodendron Kubitzki & H. G. Richt., a relationship confirmed by molecular study (Rohwer 2000; Rohwer & Rodolph 2005) and morphological and wood anatomy analyses (Kubitzki & Richter 1987). The two genera have leaves clustered at the tips of the branches, bisexual flowers with three fertile stamens representing the third androecial whorl and fruit with a minute discoid cupule. The main difference between the two genera is found in the anthers: Mezilaurus possesses 2-locular anthers, while in Williamodendron they are 4-locular. Kubitzki & Richter (1987) described Williamodendron including two 4-locular species that van der Werff (1987) had treated as Mezilaurus, and listed also differences in wood and bark anatomy. Mezilaurus itauba (Meisn.) Taub. ex Mez, the “itauba”, is the preferred wood for construction of boats in Amazonia due its high durability and resistance (Vicentini et al. 1999). In the Atlantic forest, the only previously species known of the genus, M. navalium (Allemão) Taub. ex Mez, the “tapinhoã”, is also excellent for naval construction, manufacture of furniture and for all types of durable constructions (Record & Hess 1942). Both species are considered vulnerable to extinction (IUCN 2001). In Brazil, the Atlantic forest is considered one of the biomes most endangered in the world (Mori 1989) and has received high priority for conservation of its biodiversity (Bibby et al. 1992). The south of the state of Bahia possesses areas of great diversity and ende- mism, but it is estimated that only 0.4% of the original Bahian coastal forests remains intact (Thomas et al. 1998). Current studies on the Lauraceae of Bahia have revealed a new species of Mezilaurus for the Brazilian Atlantic Forest, the first for the northeast region of Brazil, its description follows below. Accepted for publication November 2011. 1 Universidade de São Paulo, Herbário ESA (ESALQ), Av. Pádua Dias 11, Caixa Postal 9. 13418900, Piracicaba, SP, Brazil. e-mail: flaurace@yahoo.com.br 2 Universidade Estadual de Feira de Santana, Departamento de Ciências Biológicas, Laboratório de Sistemática Molecular de Plantas, Av. Trasnordestina s.n. Novo Horizonte, 44036-900, Feira de Santana, BA, Brazil. KEW BULLETIN VOL. 66: 505–509 (2011) © The Board of Trustees of the Royal Botanic Gardens, Kew, 2012