A new genus and two new species of Opilioacaridae (Acari: Parasitiformes) from Amazonia, Brazil with a key to world genera.

Collections of Opilioacaridae made close to 50 years ago in Manaus in the Amazonian Region have allowed the description of a new genus and two new species from Brazil, Amazonacarus setosus n.gen, n.sp. and A. paraensis n.gen, n.sp. These species show a unique combination of characters in the Opilioacaridae: a high number of foliate setae (10) on the palp tarsus with each seta bearing many lobes (6-7), a group of large, serrate setae (26-31) on the palp tibia (this group of setae is much smaller in other species), and 5-7 dorsal setae on idiosomal segment XVIII. Indiacarus and some Opilioacarus show 3-5 setae on segment XVIII, but these genera (and Caribeacarus) have fewer foliate setae on the palp (3-4). Females of Amazonacarus have an ovipositor of the "complex" type, with spiny projections and 2-4 genital setae, while males have two pairs of rounded, large glands.