In an effort to understand the fauna of edaphic mites of the genus Lasioseius Berlese (Blattisociidae) from Brazil, a new species was found and it is here described as Lasioseius biota Barros & Castilho sp. nov. It is rather unusual among the Lasioseius species for having dorsal setae mostly bacillate or saber- to leaf-shapped. The other species considered in this paper is Lasioseius meridionalis Chant, morphologically known only from the original description, based solely on the holotype female (from USA). Information resulting from the reexamination of the holotype and on females collected from Brazil is provided. This is the first record of this species in Brazil. With this publication, the total number of Lasioseius species reported from Brazil adds to 19 and a key for the separation of females of these species is provided.