Based on morphological and molecular studies of material from caves in three karst regions of Crimea, the small, apparently relictual, Euro-Mediterranean and Macaronesian false scorpion genus Pseudoblothrus Beier, 1931 is shown to contain only one troglobiont species there, P. roszkovskii (Redikorzev, 1918), of which P. ljovuschkini Krumpál, 1984 and Obisium tauricum Lebedev, 1927 are junior subjective synonyms. A detailed redescription of the adults and tritonymph of P. roszkovskii is provided, together with phylogenetic and zoogeographical analyses.

Two new species of the mite genus Histiogaster—H. litoralis sp. n. and H. tareevi sp. n.—are described from Eastern Russia based on males and females. Histiogaster ornata are redescribed based on males, females and heteromorphic deutonymphs. For H. litoralis, pre-copulatory guarding of tritonymphs is reported based on observations in a laboratory culture. This contrasts with the mites from the H. arborsignis species group which lacking this behavior. An annotated checklist and a key to the species of Histiogaster from the Eastern Palearctic are provided.

Most species of the mite genus Winterschmidtia Oudemans, 1923 are associated with bark beetles. These mites are predacious on eggs of their coleopteran hosts and may be potential biocontrol agents for pest species of bark beetles. Here we describe three new species of Winterschmidtia from Peru based on phoretic deutonymphs: W. parallela sp. nov. (from Loganius flavicornis), W. alekhini sp. nov. (from Phloeotribus biguttatus) and W. reducta sp. nov. (from Phloeotribus pilula). The name Calvolia fusiformis Zachvatkin, 1941 was recombined as Winterschmidtia fusiformis (Zachvatkin, 1941) com. nov. An illustrated key to species of the genus Winterschmidtia (phoretic deutonymphs) of the world is provided.