Abstract Steneotarsonemus concavuscutum sp. nov. (Acari: Tarsonemidae) was described from adult females and males collected on Cocos nucifera L. in northeastern Brazil. This species was distinguished from other species of the genus Steneotarsonemus by the strong concave posterior margin of the prodorsal shield of females. This new species was more abundant during dry season in that region. The damage on coconut fruits caused by S. concavuscutum was observed as necrotic longitudinal bands.