Microhabitat distribution of arboreal oribatid mites (Oribatida), associated with the Siberian pine (Pinus sibirica) of Western Siberia

Diversity and Distribution of Mites (ACARI) Revealed by Contamination Survey in Public Genomic Databases

Acari (mites and ticks) are a biodiverse group of microarthropods within the Arachnida. Because of their diminutive size, mites are often overlooked. We hypothesized that mites, like other closely related microorganisms, could also contaminate public genomic database. Here, using a strategy based on DNA barcodes previously reported, we scanned contaminations related to mites (Acari, exclusive of Ixodida) in Genbank WGS/TSA database. In 22,114 assemblies (17,845 animal and 4269 plant projects), 1717 contigs in 681 assemblies (3.1%) were detected as mite contaminations. Additional taxonomic analysis showed the following: (1) most of the contaminants (1445/1717) were from the specimens of Magnoliopsida, Insecta and Pinopsida; (2) the contamination rates were higher in plant or TSA projects; (3) mite distribution among different classes of hosts varied considerably. Additional phylogenetic analysis of these contaminated contigs further revealed complicated mite-host associations. Overall, we conducted a first systemic survey and analysis of mite contaminations in public genomic database, and these DNA barcode related mite contigs will provide a valuable resource of information for understanding the diversity and phylogeny of mites.

Taxonomic contribution to the knowledge of the oribatid mite family Scheloribatidae (Acari, Oribatida), with description of three new species from Vietnam

Three new oribatid mite species of the family Scheloribatidae (Oribatida)Dometorina (Dometorina) robusta sp. nov., Phylloribatula latiseta sp. nov., Scheloribates (Scheloribates) paraflagellisetosus sp. nov.are described, based on adults collected from tree branches of Dipterocarpus alatus in southern Vietnam. Representatives of Dometorina (Dometorina) and Phylloribatula are recorded in the Vietnamese fauna for the first time. An identification key to the known species of Phylloribatula is provided.

Contribution to knowledge of the oribatid mite genus Symbioribates (Acari, Oribatida, Symbioribatidae), with descriptions of two new arboreal species from Vietnam

The family Symbioribatidae is recorded in Vietnam for the first time. Two new arboreal species of SymbioribatesS. bimorphus sp. nov. and S. tripartitus sp. nov.are described, based on adults (males and females) collected from tree branches of Dipterocarpus alatus in Cat Tien National Park, Vietnam; the former species is sexually dimorphic, the latter species is the first non-sexually dimorphic representative within the genus. The generic diagnosis is presented. An identification key, distribution and habitats to the known representatives of Symbioribates are provided.

Ontogenetic instars of Phyllhermannia bimaculata Hammer, 1979 (Acari, Oribatida, Hermanniidae)

The morphology of juvenile instars (larva, proto-, deuto- and tritonymph) of the Oriental oribatid mite species Phyllhermannia bimaculata Hammer, 1979 (Oribatida, Hermanniidae) is studied, based on arboreal material from southern Vietnam. The SEM micrographs and morphological traits summarized for adults of P. bimaculata are presented. Juveniles of P. bimaculata are compared to those of other known species of the genus.

New species of Flagellozetes (Cosmogalumna) (Acari, Oribatida, Galumnidae) from Vietnam

Two new species of the genus Flagellozetes (Oribatida, Galumnidae) – F. (Cosmogalumna) carinodentatus sp. n. and F. (C.) pseudoareticulatus sp. n. – are described from the bark of different trees in Vietnam. A comparative analysis of the F. (Cosmogalumna) group included species with neural ridges on the notogaster is presented.

Mite gut microbiome and resistome exhibited species-specific and dose-dependent effect in response to oxytetracycline exposure

The importance of the gut microbiome to host health is well recognized, but the effects of environmental pressures on the gut microbiome of soil fauna are poorly understood. Here, Illumina sequencing and high-throughput qPCR were applied to characterize the gut microbiomes and resistomes of two mites, Nenteria moseri and Chiropturopoda sp. AL5866, exposed to different concentrations of oxytetracycline (0, 0.01, 0.1 and 1 μg mg^-1). Proteobacteria, Bacteroidetes, Actinobacteria and Firmicutes were the dominant phyla in the gut microbiomes of both studied mite species, but the relative abundance of them was different between mites. After exposure to oxytetracycline, there was no variation in the gut microbiome and resistome of C. sp. AL5866, whereas the gut microbiome and resistome of N. moseri were altered significantly. The relative abundance of Proteobacteria significantly decreased, and those of Bacteroidetes and Firmicutes significantly increased at the high-concentration antibiotic treatments. Excepting the 0.01 μg mg^-1 treatment, gut microbial diversity increased with ascending concentrations. A significant resistome enrichment of relative abundance in N. moseri gut microbiome at low-dose antibiotic treatment was noted. These results indicated that the gut microbiome in N. moseri was potentially more sensitive to antibiotics than C. sp. AL5866, which was supported by the greater relative abundance of key tetracycline-resistant genes in the gut microbiome of C. sp. AL5866 compared to N. moseri. Mite gut microbiomes were correlated with their associated resistomes, demonstrating the consistent changes between microbiome and resistome. Thus, this study showed that oxytetracycline amendment resulted in a dose-dependent and species-specific effect on the gut microbiomes and resistomes of two mite species. It will contribute to understanding the relationship between the soil mite gut microbiome and resistome under antibiotic exposure, and extend our knowledge regarding the emergence and transfer of resistomes in soil food webs.

Revisiting the Evolution of Arboreal Life in Oribatid Mites

Though mostly soil dwelling, oribatid mites are found in all kind of habitats, with several species exclusively living on trees. Using previously published DNA sequences and eco-morphological data available from the literature, we inferred the number of transitions between soil dwelling to a truly arboreal lifestyle in oribatid mites and the shape evolution of a particular morphological structure of a sense organ (bothridial seta (= sensillus) of a trichobothrium), the shape of which was previously reported to be associated with an arboreal lifestyle. Our data suggest that a truly arboreal lifestyle evolved several times independently in oribatid mites, but much less often than previously proposed in the past. Even though all truly arboreal species indeed seem to possess a capitate sensillus, this character is not exclusive for arboreal taxa. Nonetheless, since all truly arboreal species do have a capitate sensillus, this might be considered an important (pre-)adaptation to a life on trees. We further provide guidelines on how the term “arboreal” should be applied in future mite research and emphasize the importance of exact microhabitat characterization, as this will greatly facilitate comparisons across studies.