ABSTRACT Lowland forests, also known as tabuleiro forests, are the predominant phytophysiognomy in the Atlantic Coastal Forest in northeastern Brazil. We inventoried the Orchidaceae present in the northern section of those forests, from the state of Rio Grande do Norte until the southern region of the state of Pernambuco. We examined specimens from seven regional herbaria and undertook field expeditions to four conservation units in the region. A total of 65 species belonging to 36 genera and to subfamilies Epidendroideae (44 species), Orchidoideae (16), and Vanilloideae (5) were identified. The most diverse genera are Epidendrum e Habenaria, with eight and seven species, respectively. Native species represented 96 % of the total observed, with 27 % being endemic to Brazil. Epiphytic (35) and terrestrial (27) species predominated; only three species are hemiepiphytic. We registered 14 new records of species for Rio Grande do Norte, two for Paraíba, and one for Pernambuco. Diagnoses of genera and species, as well as an identification key, data on geographic distribution, taxonomic and ecological comments, conservation status, and photos of the species are provided.

Resumo A Mata do Buraquinho, situada no município de João Pessoa, com aproximadamente 520 ha, é um dos principais remanescentes de Floresta Atlântica no estado da Paraíba. Este trabalho teve como objetivo inventariar e descrever as espécies de Orchidaceae presentes nesta mata, visando fornecer informações sobre a riqueza e formas de vida da família predominantes nesse ambiente. Para o levantamento das espécies foram realizadas caminhadas por trilhas já existentes, observadas as populações in situ e coletadas aquelas em estágio reprodutivo, além da consulta de espécimes herborizados. O levantamento revelou a presença de 11 espécies reunidas em oito gêneros. O gênero mais diverso foi Vanilla com três espécies. Epidendrum micronocturnum, espécie disjunta amazônico-atlântica, é um novo registro para o estado da Paraíba. É apresentada uma chave para identificação das espécies, bem como descrições, ilustrações e comentários a respeito das mesmas.

Abstract The Mata do Buraquinho, located in the municipality of João Pessoa, with ca. 520 ha, is one of the most representative remnants of the Atlantic Forest in the state of Paraíba. The objective of this work was to inventory and describe the species of Orchidaceae present in this forest, aiming to provide information on the family’s richness and prevailing life forms in this environment. In order to survey the species, we walked along existing trails, observing in situ populations and collecting those fertile, and analyzed herbarium specimens. The survey revealed the presence of 11 species and eight genera. The most diverse genus was Vanilla with three species. Epidendrum micronocturnum, a disjunct Amazonian-Atlantic species, is a new record for the state of Paraíba. A key to identify the species is presented, as well as descriptions, illustrations and comments on the species studied.