Conceptual and nomenclatural problems of Digamasellus Berlese, 1905 and Dendrolaelaps Halbert, 1915 are reviewed. It is shown that Digamasellus punctum (Berlese, 1904) is conspecific with D. perpusillus Berlese, 1905, the type-species of Digamasellus Berlese, 1905 (new synonymy). Hence, the genus in which punctum is included must take the name Digamasellus.A new case is made for recognizing Digamasellus and Dendrolaelaps as distinct genera in the Digamasellidae. Two other genera of Digamasellidae are recognized, Dendroseius Karg, 1965 and a broadened concept of Longoseius Chant, 1961. Two new subgenera are proposed, Dendrolaelaspis in the genus Dendrolaelaps, and Longoseiulus in the genus Longoseius. Diagnoses, descriptions, and a key to these genera and subgenera of Digamasellidae, along with a comprehensive description of the family, are presented. The phylogenetic relationship of the Digamasellidae in the Rhodacaroidea, and some thoughts on phylogeny within the Digamasellidae are given.A second species of Digamasellus sensu stricto, D. australis, is described as new, and the female and male adults of the type-species of Longoseius, L. (L.) cuniculus Chant, are described for the first time. New combinations include: Dendrolaelaps (Dendrolaelaspis) orientalis (Bhattacharyya), Longoseius (Longoseiulus) longulus (Hirschmann), L. (L.) ornatus (Hirschmann), L. (L.) aberrans (Hirschmann), and L. (L.) brachypoda (Hurlbutt).The absence of the protonymphal seta, md, from the telotarsi of legs II to IV is noted as a singular deficiency in the leg setation of Longoseius cuniculus Chant. This seta is not known to be absent in any other species among the families of Gamasina.A paper published by Hirschmann while the present work was in press is considered in an addendum to this paper. The subgeneric name Dendrolaelaps (Tridendrolaelaps) Hirschmann, 1974 is an objective junior synonym of Digamasellus Berlese, 1905, and the latter also has priority over Dendrolaelaps Halbert, 1915 so long as both names are applied within the same genus. A lectotype is designated for the nominal species Digamasellus punctum (Berlese). The status of the subgenus Dendrolaelaps (Multidendrolaelaps) Hirschmann, 1974 is problematic, pending a more comprehensive diagnosis providing data sufficient to indicate whether this is a monophyletic group. The quadrisetus group is newly proposed for some of the species placed by Hirschmann in the armatus group of Multidendrolaelaps. Digamasellus badenhorsti (Ryke) is tentatively considered as the second known species of Dendroseius Karg. Hirschmann's opinion, that Longoseius Chant warrants no more than a species-group in Dendrolaelaps, is disputed.