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The status of the genera in the small microtrombidiid mite tribe Hexathrombiini is reevaluated. Type specimens representing all genera were studied and diagnostic characters for Hexathrombiini are reviewed, summarized, and new data and a key to the genera in the tribe are provided: Alhamitrombium, Beronium, Hexathrombium and Hoplothrombium. Hexathrombium is the most speciose genus in the tribe and species recorded from South America are compared, as well as those with a divided pygidial plate. A provisional key to species assigned to Hexathrombium is provided. Finally, Hexathrombium abirami was captured in Peru parasitizing a bright metallic tiger beetle (Tetracha fulgida). A total of 361 larvae were removed parasitizing a single carabid host; this is the highest load of parasites reported in terrestrial Parasitengona mites associated with arthropods. This capture represents a new record of Hexathrombiini mites for Peru. A redescription of He. abirami using all specimens available to date is included.

An unusually large acariform mite is described as Immensmaris chewbaccei gen. et sp. nov. from the Cretaceous (ca. 100 Ma) Burmese amber of Myanmar. With an idiosoma plus gnathosoma more than a centimetre long, it represents the largest unequivocal fossil mite ever recorded and approaches the maximum size of the largest living Acariformes today. Although some details of the dorsal idiosoma are equivocal, the new fossil appears to belong to Smarididae (Prostigmata: Parasitengona: Erythraeoidea) and also represents the largest erythraeoid mite ever discovered, indicating a clade of giant, possibly arboreal, mites in the Late Cretaceous of southeastern Asia.

Larval trombiculid (chigger) mites are common ectoparasites of terrestrial vertebrates including humans, causing itching and skin inflammation known as trombiculiasis. Investigation of their diversity, distribution and seasonal abundance is therefore important from a veterinary and public health point of view. Although researchers have paid increased attention to these parasites in recent years, there is still little ecological data available on chiggers associated with birds inhabiting different types of habitats such as wetlands, for example. In 2021, we investigated the mite fauna in a specialist reedbed passerine, the bearded tit ( Panurus biarmicus ), and their effects on this host in the south-west Slovakia, Central Europe. A total of 1134 larvae of 1 mite species Blankaartia acuscutellaris were found in 99 out of 267 examined bearded tits. Juveniles were more infested than adult birds, but no differences were found between sexes. The larvae of mites first appeared on the host during the second half of June and peaked in the second half of July. After that, their numbers decreased gradually until October. Despite the relatively high prevalence and intensity of mite infestation in the bearded tit, no differences in body condition between infested and uninfested birds suggest that infestation by B. acuscutellaris may not have serious negative effects on the host health. Bearded tits can therefore be a reliable indicator of the presence of the chigger mites in wetland habitats.

Arachnid orders, Mesostigmata, Trombidiformes, and Sarcoptiformes, commonly known as 'mites', are abundant in mires, both as adults and as juveniles. However, due to the challenges of identification, the juvenile forms are often excluded from analyses. This is the first study in mires that included all three mite orders identified to the species level, including juvenile instars. We aimed to compare how diversity and the response to ecological variables differed if only the adults (ad) vs. the total number of specimens (ad+juv) are considered. Samples of 20 Sphagnum species (five subgenera) were collected and mites were extracted using Berlese funnels. Overall, nearly 60,000 mites were analyzed; of these Mesostigmata made up 1.87% of the total, Trombidiformes -0.27%, and Sarcoptiformes -97.86%. The study revealed 154 species (33 Mesostigmata, 24 Trombidiformes, and 97 Sarcoptiformes), the highest diversity of mites ever reported from mires. The inclusion of juveniles increased observed species richness by 6%, with 10 species (one Mesostigmata, six Trombidiformes, and three Sarcoptiformes) represented only by juvenile forms. Seventeen species are new to Norway (four Mesostigmata, one Sarcoptiformes, and 12 Trombidiformes, including five undescribed species of Stigmaeidae and Cunaxidae). Four of these were represented in the samples only by juveniles. Including the juveniles explained a greater amount of the variability of Trombidiformes (explanatory variables account for 23.60% for ad, and 73.74% for ad+juv) and Mesostigmata (29.23% - ad, 52.91% - ad+juv), but had less of an impact for Sarcoptiformes (38.48% - ad, 39.26% - ad+juv). Locality, Sphagnum subgenus and species, wetness, and trophic state significantly affected the mite communities and should be taken into consideration when studying mires. Since juvenile stages contribute significantly to mite diversity in mires, they should also be included in mite studies in other habitats., (© 2022 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.)

The knowledge of terrestrial Parasitengona in Fennoscandia lies far behind that of their aquatic counterparts, the water mites (Hydrachnidia). Based on new inventories, we provide primary data and an annotated checklist of terrestrial Parasitengona in Fennoscandia including 107 species. Out of these, nineteen species are new findings for the region and five are species potentially new for science. Twenty-three species are new for Norway, fourteen for Finland and eleven for Sweden. The known recorded fauna today of terrestrial Parasitengona is 80 species for Norway, 54 for Sweden and 48 for Finland. Primary data include georeferenced locality data as well as collecting techniques and microhabitat to increase the knowledge on species' habitat requirements.

Background: The time-extended contact of trombiculid larvae with hosts poses a question of its ecological determinants. The phenomenon, which may facilitate the overwintering of larvae in the temperate zone, was previously observed in few parasitengone taxa, but not confirmed for mammal-associated trombiculids. The study aims at tracing the phenology of larvae of Hirsutiella zachvatkini and at verifying the hypothesis of contact with the host, extending beyond the parasitic phase., Methods: Apodemus agrarius, Apodemus flavicollis and Myodes glareolus, trapped during 2-year studies, were checked for the presence of trombiculid larvae. Larvae of H. zachvatkini served for the studies. The degree of mites' engorgement was checked over time in order to estimate the duration of feeding phase and to measure the maximum size increase. The experimental rearing aimed at ascertaining the relations between the level of engorgement and successful transformation of larva into subsequent instar., Results: The mass appearance of larvae on hosts fell on autumn and winter, with a decrease observed in spring, leading to an almost total absence in early and mid summer. The highest intensity, attained in late autumn or in winter, was not followed by further increase in the number of host-associated larvae. The percentage of unengorged larvae on hosts was disproportionately small, irrespective of the season. The size increase of larva was 12.6-fold at maximum. Engorged or partly engorged larvae, observed from the beginning of mass appearance over the entire period of host-parasite association in the field, transformed into subsequent instar when removed from host., Conclusions: An increase in intensity observed from the onset of appearance of larvae on hosts, through autumn and winter months, at rarity of observations of unengorged larvae and absence of engorged larvae off-host, indicates a prolonged contact with hosts, aimed at synchronisation of life cycle, conditioned by food resources available for active postlarval forms and constitutes a strategy enabling larvae to survive the unfavourable winter conditions. The proportion of engorged and partly engorged vs. unfed larvae, observed over the survey, along with their ability to transform into subsequent instars, indicates a relatively short feeding phase. The lack of continuous increase in abundance and intensity towards spring and summer suggests a gradual detachment of partly and fully engorged larvae which attained the readiness to subsequent development. The size increase of larvae during their parasitic phase does not corroborate the neosomy in H. zachvatkini. Host-associated differences in topic preferences of the chiggers become less obvious at maximum infection rates. Quantitative descriptors of parasite population place M. glareolus among the most infected hosts of H. zachvatkini in contrast to Apodemus mice collected in the same habitat.

Descriptions of Dambullaeus adonis Mąkol et Moniuszko SP NOV: (Trombidiformes: Erythraeidae, Callidosomatinae) and Latois nigrolineata Świerczewski et Stroiński SP NOV: (Hemiptera: Fulgoromorpha, Flatidae) from Madagascar are provided. The first host record for ectoparasitic larvae of Dambullaeus Haitlinger, 2001 and the first evidence on host-parasite association between flatid adult and erythraeid larvae are given. Genus Dambullaeus, known exclusively from larvae and now comprising two species of Gondwanan distribution, is critically reappraised., (© The Author 2014. Published by Oxford University Press on behalf of the Entomological Society of America.)