The Serra Arqueada, in the municipalities of Ourilândia do Norte and Sao Felix do Xingu, in southeastern Para state, Brazil, has an extension of c. 50 km and reaches altitudes between 450 and 689 m above sea level. This range harbours outcrops of campo rupestre on canga, an iron-rich substrate, which were not studied in the Flora of the canga of the Serra de Carajas (FCC) project. We present here the first botanical survey of this site, with the main objective to document its plant diversity. We also aim to improve our knowledge of species distribution, biogeographical relationships and conservation of the canga within the Carajas Mineral Province. Our results indicate the occurrence of 153 angiosperm species representing 53 families. This study also reveals the occurrence of two species previously not reported for Para: Scaphyglottis livida (Orchidaceae) and Rhynchospora exilis (Cyperaceae). We compare the floristic composition of canga areas from Serra Arqueada with similar sites from the Serra dos Carajas and find Serra Arqueada safeguards at least eight edaphic endemic species from the canga of the FCC region. Moreover, there is a high number of microhabitats in the area, which is probably related to the relative distinct and diverse flora. These data highlight the importance of conversation in the area, safeguarding these species and microhabitats. We conclude Serra Arqueada represents an appropriate site for conservation purposes.