The present work provides descriptions of a new species of mite, Centrouropoda bahariyaensis n. sp. (Uropodidae), based on the adult female and male collected from the red palm weevil, Rhynchophorus ferrugineus (Oliver) (Coleoptera Curculionidae) and its habitat at El-Bawiti, Bahariya Oasis, Egypt. Complete descriptions of the immature stages are included. Keys to the known species of genus Centrouropoda Berlese based on adult females, adult males and deutonymphs are provided.The Mexican species of the genus Orthocentrus Gravenhorst are reviewed. Fortytwo species of the genus Orthocentrus are described as new O. areolatus sp. nov., O. aztecus sp. nov., O. brevicornis sp. nov., O. collaris sp. nov., O. contrerasi sp. nov., O. coronadoae sp. nov., O. dorsofuscus sp. nov., O. elongatus sp. nov., O. flavoorbitalis sp. nov., O. fuscipes sp. nov., O. hidalgoensis sp. nov., O. kasparyani sp. nov., O. khalaimi sp. nov., O. latus sp. nov., O. longiventris sp. nov., O. lopezi sp. nov., O. lostuxtlasi sp. nov., O. malaris sp. nov., O. mexicanus sp. nov., O. microphthalmus sp. nov., O. minor sp. nov., O. montanus sp. nov., O. montezuma sp. nov., O. oaxacae sp. nov., O. ocampo sp. nov., O. pictus sp. nov., O. podagricus sp. nov., O. rhombifer sp. nov., O. rufipleuris sp. nov., O. ruizi sp. nov., O. scabrosus sp. nov., O. scutellatus sp. nov., O. sierrae sp. nov., O. similis sp. nov., O. tamaulipecus sp. nov., O. tergalis sp. nov., O. tlaxcalensis sp. nov., O. ungularis sp. nov., O. varicolor sp. nov., O. veracruzus sp. nov., O. vulgaris sp. nov., O. zaldivari sp. nov. In total, 53 Orthocentrus species are now known to occur in Mexico, and 52 species are reported from Mexico for the first time. A key to all known species of Mexican Orthocentrus is provided and distribution maps are presented.The taxonomy of Venezuelan water beetles in the genus Hydrochus Leach, 1817 is presented. The known fauna now consists of 26 species, 17 of which are described as new species. All species are described, or redescribed, diagnosed, and high-resolution images of the habitus and male genitalia of each species are given. The morphology and mechanics of the male genitalia of Hydrochus are described and illustrated, and a system of naming male genitalia characters in Hydrochidae is provided. The following new species are described H. argutissimus n. sp., H. basilaris n. sp., H. bicarinatus n. sp., H. bituberculatus n. sp., H. collaris n. sp., H. conjunctus n. sp., H. denarius n. sp., H. formosus n. sp., H. hellmani n. sp., H. kellymilleri n. sp., H. leei n. sp., H. lobatus n. sp., H. mauriciogarciai n. sp., H. pictus new species, H. sagittarius n. sp., H. shorti n. sp., H. variabiloides n. sp. Hydrochus pseudosecretus Oliva 1996 is removed from synonymy with H. purpureus Knisch, H. soekhnandanae Makhan 1992 is removed from synonymy with H. pupillus Orchymont, and H. ramcharani Makhan 1992 is removed from synonymy with H. drakei Knisch.In the course of the present study 28 species of the genus Pseudolycoriella Menzel Mohrig, 1998 from New Zealand were described as new to science Pseudolycoriella aotearoa sp. n., Psl. dagae sp. n., Psl. dentitegmenta sp. n., Psl. fiordlandia sp. n., Psl. gonotegmenta sp. n., Psl. hauta sp. n., Psl. huttoni sp. n., Psl. jaschhofi sp. n., Psl. jejunella sp. n., Psl. kaikoura sp. n., Psl. maddisoni sp. n., Psl. mahanga sp. n., Psl. nahenahe sp. n., Psl. orite sp. n., Psl. plicitegmenta sp. n., Psl. porehu sp. n., Psl. porotaka sp. n., Psl. puhihi sp. n., Psl. raki sp. n., Psl. robustotegmenta sp. n.,Psl. subtilitegmenta sp. n., Psl. sudhausi sp. n., Psl. teo sp. n., Psl. tewaipounamu sp. n., Psl. tuakana sp. n., Psl. wernermohrigi sp. n., Psl. whakahara sp. n., and Psl. whena sp. n. Pseudolycoriella cavatica (Skuse, 1888), a widely distributed species, was recorded from New Zealand for the first time, and recognised as a senior synonym of Spathobdella setigera Hardy, 1960 syn. n. Apart from Psl. kaikoura and Psl. cavatica all New Zealand Pseudolycoriella species group in four different clusters the Psl. bispina complex, the Psl. jejuna complex, the Psl. macrotegmenta complex, and the Psl. zealandica complex. The monophyly of those four species complexes was confirmed by a genetic analysis based on two mitochondrial genes (COI and 16S) and one nuclear gene (28S). A key to the species is given.The ultor-group of the genus Dolichogenidea Viereck from China is revised, which totally 67 species are recorded. Thirty-nine new species are described and illustrated, i.e., D. alophogaster Liu Chen, sp. nov.; D. altithoracica Liu Chen, sp. nov.; D. anterocava Liu Chen, sp. nov.; D. apicurvus Liu Chen, sp. nov.; D. atarsi Liu Chen, sp. nov.; D. breviattenuata Liu Chen, sp. nov.; D. carborugosa Liu Chen, sp. nov.; D. clausa Liu Chen, sp. nov.; D. MMP inhibitor conpuncta Liu Chen, sp. nov.; D. crassa Liu Chen, sp. nov.; D. cucurbita Liu Chen, sp. nov.; D. excellentis Liu Chen, sp. nov.; D. flexitergita Liu Chen, sp. nov.; D. fluctisulcus Liu Chen, sp. nov.; D. flexisulcus Liu Chen, sp. nov.; D. gleditsia Liu Chen, sp. nov.; D. hemituba Liu Chen, sp. nov.; D. hexagona Liu Chen, sp. nov.; D. infirmus Liu Chen, sp. nov.; D. latitergita Liu Chen, sp. nov.; D. lincostulata Liu Chen, sp. nov.; D. lobesia Liu Chen, sp. nov.; D. longialba Liu Chen, sp. nov.; D. longimagna Liu Chen, sp. nov.; D. lunatus Liu Chen, sp. nov.; D. medica Fifteen new host are recorded for the following previously described species viz., D. baoris, D. brevicarinata, D. expulse, D. heterusiae, D. hyposidrae, D. kurosawai, D. lacteicolor, and D. prisca and marked by a number sign (#). Eleven new host associations are documented for the following new species D. alophogaster; D. crassa, D. flexisulcus; D. gleditsia; D. hexagona; D. lincostulata; D. lobesia; D. minuscula; D. multicolor; D. obsolete, and D. rectivena. The hosts of thirty-two species remain unknown. An identification key and distribution maps to the Chinese species of the ultor-group is provided.Leptomeson Jeannel, 1924, originally treated as a subgenus of Anthroherpon Reitter, 1889 (Jeannel, 1924), was erected to a distinct genus by Guéorguiev (1990). It currently includes 13 endemic taxa (nine species and four subspecies) (Perreau, 2015), of which five species are recently described (Giachino et al., 2011). All Leptomeson taxa are troglobitic, montane or insular, and are distributed in a narrow Dinaric area in the proximity to the Adriatic Sea coast belonging to Croatia and Bosnia and Herzegovina (Perreau, 2000; Giachino et al., 2011) (Fig. 1).