Flora of the cangas of Serra dos Carajás, Pará, Brazil: Rubiaceae

Abstract

The present study comprises the Rubiaceae that occur on iron-stone (canga) at Serra dos Carajás, estado do Pará, Brasil, including identification keys, detailed descriptions, illustrations and comments regarding the species found, as well as the synonymization of two names (Chomelia parvifolia and Tocoyena bullata). A total of 48 species distributed in 24 genera were recorded, with a predominance of members from tribe Spermacoceae in the open areas, including a monotypic endemic genus, Carajasia cangae, as well as several species with restricted distribution (e.g., Borreria carajasensis, B. elaiosulcata, B. heteranthera and Mitracarpus carajasensis). The genus Psychotria, with nine species treated, had the highest number of species found mostly in the forest groves on canga substrate.