Testing the effectiveness of different wash protocols to remove body surface contaminants in invertebrate food web studies

Molecular gut content analysis via diagnostic PCR or high-throughput sequencing (metabarcoding) of consumers allows unravelling of feeding interactions in a wide range of animals. This is of particular advantage for analyzing the diet of small invertebrates living in opaque habitats such as the soil. Due to their small body size, which complicates dissection, microarthropods are subjected to whole-body DNA extraction-step before their gut content is screened for DNA of their food. This poses the problem that body surface contaminants, such as fungal spores may be incorrectly identified as ingested food particles for fungivorous species. We investigated the effectiveness of ten methods for body surface decontamination in litter-dwelling oribatid mites using Steganacarus magnus as model species. Furthermore, we tested for potential adverse effects of the decontamination techniques on the molecular detection of ingested prey organisms. Prior to decontamination, oribatid mites were fed with an oversupply of nematodes (Plectus sp.) and postmortem contaminated with fungal spores (Chaetomium globosum). We used diagnostic PCR with primers specific for C. globosum and Plectus sp. to detect contaminants and prey, respectively. The results suggest that chlorine bleach (sodium hypochloride, NaClO, 5%) is most efficient in removing fungal surface contamination without significantly affecting the detection of prey DNA in the gut. Based on these results, we provide a standard protocol for efficient body surface decontamination allowing to trace the prey spectrum of microarthropods using molecular gut content analysis.

Mites Living in the Nests of the White Stork and Black Stork in Microhabitats of the Forest Environment and Agrocenoses

The White Stork (Ciconia ciconia) and the Black Stork (Ciconia nigra) are well-known model organisms for the study of bird migration, as well as the selectivity of nesting sites and the choice of living environment. The former breeds mainly in open areas, while the latter inhabits forest areas. The acarofauna, and in particular Oribatida, inhabiting the nests of these species, has not been thoroughly explored so far. Therefore, we analyzed the material collected from 70 White Stork nests and 34 Black Stork nests in Poland, between Poznań and Rawicz, and in Kampinos National Park. Our research has increased the faunal and ecological knowledge of the mite fauna inhabiting the nests of large migratory bird species. Oribatida constituted 5-12% of the total mites identified in the nests of White and Black Storks. Their average number was several times higher in the Black Stork nests (80.2 individuals in 500 cm3). Also, the species diversity of moss mites was greater in the Black Stork nests (47 species). In total, the nests of the two stork species were inhabited by 62 moss mite species, with only 22 recorded in both the White and the Black Storks' nests. The most numerous species included Ramusella clavipectinata, R. fasciata, Oppiella subpectinata, Acrogalumna longipluma, and Scheloribates laevigatus. In addition, we found that juvenile oribatid mites accounted for 0.6% of all the mites in the White Stork nests, with tritonymphs having the largest share, while juveniles in the Black Stork nests comprised 1.4%, of which larvae and protonymphs had the largest share. Our research shows that the nests of large migratory birds provide living space for many mite species. In addition, we noted the potential importance of White and Black Stork nests for mite dispersion and the evolution of interspecies interactions.

Impact of forest disturbance on microarthropod communities depends on underlying ecological gradients and species traits

Windstorms and salvage logging lead to huge soil disturbance in alpine spruce forests, potentially affecting soil-living arthropods. However, the impacts of forest loss and possible interactions with underlying ecological gradients on soil microarthropod communities remain little known, especially across different environmental conditions. Here we used DNA metabarcoding approach to study wind-induced disturbances on forest communities of springtails and soil mites. In particular, we aimed to test the effect of forest soil disturbance on the abundance, richness, species composition, and functional guilds of microarthropods. We sampled 29 pairs of windfall-forest sites across gradients of elevation, precipitation, aspect and slope, 2 years after a massive windstorm, named Vaia, which hit North-Eastern Italy in October 2018. Our results showed that wind-induced disturbances led to detrimental impacts on soil-living communities. Abundance of microarthropods decreased in windfalls, but with interacting effects with precipitation gradients. Operative Taxonomic Units (OTU) richness strongly decreased in post-disturbance sites, particularly affecting plant-feeder trophic guilds. Furthermore, species composition analyses revealed that communities occurring in post-disturbance sites were different to those in undisturbed forests (i.e., stands without wind damage). However, variables at different spatial scales played different roles depending on the considered taxon. Our study contributes to shed light on the impacts on important, but often neglected arthropod communities after windstorm in spruce forests. Effects of forest disturbance are often mediated by underlying large scale ecological gradients, such as precipitation and topography. Massive impacts of stronger and more frequent windstorms are expected to hit forests in the future; given the response we recorded, mediated by environmental features, forest managers need to take site-specific conservation measures.

Two Lineages of Oribatid Mites Morphologically Correspond to the Circumpolar Species Ameronothrus nigrofemoratus (Acari, Oribatida) but Differ Genetically as Distinct Species Are Revealed on the Kolguev Island

Data reported from Northern Canada were until recently the only available data on the genetic characteristics of the oribatid mite Ameronothrus nigrofemoratus, which has a circumpolar distribution on the coasts of Arctic seas. A partial cytochrome oxidase I gene (COI) mtDNA sequence was examined in mites morphologically assigned to this species from the Kolguev Island. Two highly divergent phylogenetic lineages of A. nigrofemoratus (7% divergence) were revealed, neither of which was found on the Canadian coast. Four COI amino acid substitutions distinguished one of the lineages from North American A. nigrofemoratus, corresponding to the degree of difference between A. nigrofemoratus and its sister species A. lineatus.

Trophic niche but not abundance of Collembola and Oribatida changes with drought and farming system

Higher frequencies of summer droughts are predicted to change soil conditions in the future affecting soil fauna communities and their biotic interactions. In agroecosystems drought effects on soil biota may be modulated by different management practices that alter the availability of different food resources. Recent studies on the effect of drought on soil microarthropods focused on measures of abundance and diversity. We here additionally investigated shifts in trophic niches of Collembola and Oribatida as indicated by stable isotope analysis (¹³C and ¹⁵N). We simulated short-term summer drought by excluding 65% of the ambient precipitation in conventionally and organically managed winter wheat fields on the DOK trial in Switzerland. Stable isotope values suggest that plant litter and root exudates were the most important resources for Collembola (Isotoma caerulea, Isotomurus maculatus and Orchesella villosa) and older plant material and microorganisms for Oribatida (Scheloribates laevigatus and Tectocepheus sarekensis). Drought treatment and farming systems did not affect abundances of the studied species. However, isotope values of some species increased in organically managed fields indicating a higher proportion of microorganisms in their diet. Trophic niche size, a measure of both isotope values combined, decreased with drought and under organic farming in some species presumably due to favored use of plants as basal resource instead of algae and microorganisms. Overall, our results suggest that the flexible usage of resources may buffer effects of drought and management practices on the abundance of microarthropods in agricultural systems.

Soil microarthropods respond differently to simulated drought in organic and conventional farming systems

In Central Europe, summer droughts are increasing in frequency which threatens production and biodiversity in agroecosystems. The potential of different farming systems to mitigate detrimental drought effects on soil animals is largely unknown. We investigated the effects of simulated drought on the abundance and community composition of soil microarthropods (Collembola and Oribatida and Meso-, Pro-, and Astigmata) in winter wheat fields under long-term conventional and organic farming in the DOK trial, Switzerland. We simulated drought by excluding 65% of the ambient precipitation during the wheat-growing season from March to June 2017. The abundance of Collembola and Oribatida declined more consistently in conventionally managed fields compared to organically managed fields under simulated drought. The abundance of Collembola as well as Meso-, Pro- and Astigmata, but not the abundance of Oribatida, increased in deeper soil layers due to simulated drought, suggesting vertical migration as a drought avoidance strategy. The species composition of Oribatida communities, but not of Collembola communities, differed significantly between drought treatments and between farming systems. Soil carbon content was a major factor structuring Oribatida communities. Our results suggest that organic farming buffers negative effects of drought on soil microarthropods, presumably due to higher soil carbon content and associated higher soil moisture and improved soil structure. This potential of organic farming systems to mitigate consequences of future droughts on soil biodiversity is promising and needs further exploration across larger climatic and spatial scales and should be extended to other groups of soil biota.

Wolbachia supergroup E found in Hypochthonius rufulus (Acari: Oribatida) in Poland

Data on the spread of intracellular bacteria in oribatid mites (Acari: Oribatida) are scarce. Our work fills a gap in the research on endosymbionts in this group of invertebrates and provides information on Wolbachia infection in Hypochthonius rufulus (Acari: Oribatida) from soil, litter and moss sample collected in south-eastern Poland. This is the first report of Wolbachia in H. rufulus. Phylogeny based on the analysis of the 16S rRNA, gatB, fbpA, gltA, ftsZ and hcpA gene sequences revealed that Wolbachia from H. rufulus represented supergroup E and was related to bacterial endosymbionts of Collembola. The unique sequence within Wolbachia supergroup E was detected for the 16S rRNA gene of the bacteria from H. rufulus. The sequences of Wolbachia 16S rRNA and housekeeping genes have been deposited in publicly available databases and are an important source of molecular data for comparative studies.

Repeated convergent evolution of parthenogenesis in Acariformes (Acari)

The existence of old species-rich parthenogenetic taxa is a conundrum in evolutionary biology. Such taxa point to ancient parthenogenetic radiations resulting in morphologically distinct species. Ancient parthenogenetic taxa have been proposed to exist in bdelloid rotifers, darwinulid ostracods, and in several taxa of acariform mites (Acariformes, Acari), especially in oribatid mites (Oribatida, Acari). Here, we investigate the diversification of Acariformes and their ancestral mode of reproduction using 18S rRNA. Because parthenogenetic taxa tend to be more frequent in phylogenetically old taxa of Acariformes, we sequenced a wide range of members of this taxon, including early-derivative taxa of Prostigmata, Astigmata, Endeostigmata, and Oribatida. Ancestral character state reconstruction indicated that (a) Acariformes as well as Oribatida evolved from a sexual ancestor, (b) the primary mode of reproduction during evolution of Acariformes was sexual; however, species-rich parthenogenetic taxa radiated independently at least four times (in Brachychthonioidea (Oribatida), Enarthronota (Oribatida), and twice in Nothrina (Oribatida), (c) parthenogenesis additionally evolved frequently in species-poor taxa, for example, Tectocepheus, Oppiella, Rostrozetes, Limnozetes, and Atropacarus, and (d) sexual reproduction likely re-evolved at least three times from species-rich parthenogenetic clusters, in Crotonia (Nothrina), in Mesoplophora/Apoplophora (Mesoplophoridae, Enarthronota), and in Sphaerochthonius/Prototritia (Protoplophoridae, Enarthronota). We discuss possible reasons that favored the frequent diversification of parthenogenetic taxa including the continuous long-term availability of dead organic matter resources as well as generalist feeding of species as indicated by natural variations in stable isotope ratios.

Avoidance tests with the oribatid mite Oppia nitens (Acari: Oribatida) in cadmium-spiked natural soils

Avoidance behavior can be a useful parameter for assessing the ability of organisms to escape from pollutants in their environment. For soil evaluation, a variety of invertebrates is used including the oribatid mite Oppia nitens. Here, we tested the avoidance behavior of O. nitens using a two-chamber test and an escape test with exposures to different cadmium concentrations of up to 800 mg kg^-1 dry LUFA 2.2 soil for 2, 4, and 6 days, and up to 7 weeks. With the two-chamber method, the oribatid mites had the choice between clean and polluted soils, whereas they were allowed to escape from a box with polluted soil to clean containers without soil with the escape method. Avoidance of cadmium was observed after 2 days in both tests and the net response of the mites in the two-chamber test increased with increasing cadmium exposure concentrations. Mite responses varied through time, especially with the escape method; with the avoidance behavior becoming more variable and overall non-significant with longer test durations. This is the first study investigating the escape test simultaneously with long-term avoidance of cadmium by O. nitens. This mite species is a promising species for avoidance testing in soil ecotoxicology, but more experiments are needed to evaluate the factors that influence its responses in laboratory tests and the consequences for its distribution in contaminated ecosystems.

Mites and ticks of reptiles and amphibians in Brazil

This study focuses on the parasitic associations of mites and ticks infesting reptiles and amphibians through a multifocal approach. Herein, reptiles (n= 3,596) and amphibians (n= 919) were examined to ensure representativeness of the Brazilian herpetofauna megadiversity. The overall prevalence was calculated to better understand which were the preferred hosts for each order of Acari (Trombidiformes, Mesostigmata and Ixodida), as well as to determine which orders frequently parasitize reptiles and amphibians in Brazil, and their host specificity. Infestation rates were calculated [prevalence, mean intensity (MI) and mean abundance (MA)] for each order and species, determining which mites and ticks are more likely to be found parasitizing the ectothermic tetrapod fauna. Parasitic niches and preferred locations were recorded to help identify specific places exploited by different Acari, and to determine the host-parasite adaptations, specificity, and relationships in terms of co-evolution. In total 4,515 reptiles and amphibians were examined, of which 170 specimens were infested by mites and ticks (overall prevalence of 3.8%). Trombidiformes mites were prevalent in lizards (55.3%), followed by Ixodida on snakes (24.7%). Mesostigmata mites were the less prevalent, being identified only on Squamata reptiles (4.3% on snakes, 2.4% on lizards). In amphibians, Ixodida ticks were the most prevalent (63.2%), followed by Trombidiformes (34.6%), and lastly Oribatida (2%). From the 13 species of Trombidiformes identified, Eutrombicula alfreddugesi (19.9%) was the most abundant in terms of number of host species and infested individuals. Specimens of Ixodida, yet more common, showed low preferred locations and different values of infestation rates. Co-infestations were recorded only on snakes. Lizard mites generally adhered to the ventral celomatic area (Pterygosomatidae), and some species to the pocket-like structures (Trombiculidae). Lizards, at variance from snakes, have adapted to endure high parasitic loads with minimum effects on their health. The high number of mites recorded in the digits of toads (Cycloramphus boraceiensis, Corythomantis greening, Cycloramphus dubius, Leptodactylus latrans, Melanophryniscus admirabilis) could lead to avascular necrosis. Frogs were often infested by Hannemania larvae, while Rhinella toads were likely to be infested by Amblyomma ticks. Of note, Rhinella major toad was found infested by an oribatid mite, implying first a new parasitic relationship. The effect of high parasitic loads on critically endangered species of anurans deserves further investigation. Our results add basic knowledge to host association of mites and ticks to Brazilian reptiles and amphibians, highlighting that routine ectoparasite examination is needed in cases of quarantine as well as when for managing reptiles and amphibians in captivity given the wide diversity of Acari on the Brazilian ectothermic tetrapod fauna.

Variation in trophic niches of oribatid mites in temperate forest ecosystems as indicated by neutral lipid fatty acid patterns

Shifting of trophic niches of soil microarthropods may allow them to adapt to changing resource conditions as induced by global change processes. However, the capability of microarthropods to shift their trophic niches is little studied. Whereas some studies based on stable isotopes (¹⁵N/¹³C) point to distinct and narrow trophic niches, others indicate that trophic niches are plastic. Here, we investigated shifts in trophic niches of oribatid mites (Oribatida, Acari), a major soil detritivore microarthropod group, due to forest management, i.e., plantation of beech and spruce forests in Central Europe, using neutral lipid fatty acid (NLFA) markers. Due to differential microbial communities, we expected a fungi-based diet of oribatid mites in beech forest, but more bacterial contributions to the diet in spruce forest. Supporting these hypotheses, NLFA markers indicated that the trophic niches of each of the studied oribatid mite species differed between beech and spruce forests and shifted from feeding predominantly on litter and fungi in beech forest to more intensively feeding on bacteria in spruce forest. Oribatid mite species with the most pronounced differences in trophic niches included Achipteria coleoptrata, Eupelops hirtus, Eupelops plicatus and Liacarus xylariae, which had been classified as primary or secondary decomposers in previous studies. Overall, the results indicate that the ability of oribatid mite species to colonize different habitats and ecosystems is due to their ability to adjust their diet, i.e., to trophic plasticity. Changes in trophic niches in each of the studied oribatid mite species suggest that detritivores in soil may better cope with future changes in environmental conditions and associated changes in resource composition than species above the ground.

An Opto-electronic Sensor-ring to Detect Arthropods of Significantly Different Body Sizes

Arthropods, including pollinators and pests, have high positive and negative impacts on human well-being and the economy, and there is an increasing need to monitor their activity and population growth. The monitoring of arthropod species is a time-consuming and financially demanding process. Automatic detection can be a solution to this problem. Here, we describe the setup and operation mechanism of an infrared opto-electronic sensor-ring, which can be used for both small and large arthropods. The sensor-ring consists of 16 infrared (IR) photodiodes along a semicircle in front of an infrared LED. Using 3D printing, we constructed two types of sensor-ring: one with a wider sensing field for detection of large arthropods (flying, crawling, surface-living) in the size range of 2-35 mm; and another one with a narrower sensing field for soil microarthropods in the size range of 0.1-2 mm. We examined the detection accuracy and reliability of the two types of sensor-ring in the laboratory by using particles, and dead and living arthropods at two different sensitivity levels. For the wider sensor-ring, the 95% detectability level was reached with grain particles of 0.9 mm size. This result allowed us to detect all of the macroarthropods that were applied in the tests and that might be encountered in pest management. In the case of living microarthropods with different colors and shapes, when we used the narrower sensor-ring, we achieved the 95% detectability level at 1.1 mm, 0.9 mm, and 0.5 mm in the cases of F. candida, H. nitidus, and H. aculeifer, respectively. The unique potential of arthropod-detecting sensors lies in their real-time measurement system; the data are automatically forwarded to the server, and the end-user receives pest abundance data daily or even immediately. This technological innovation will allow us to make pest management more effective.

Trophic structure of a tropical soil- and litter-dwelling oribatid mite community and consistency of trophic niches across biomes

The trophic positions of the most abundant soil- and litter-dwelling oribatid mite species in a tropical monsoon forest in Dong Nai (Cat Tien) National Park, southern Vietnam, were estimated using stable isotope analysis. Previously published data and Layman's metrics were used to compare the structure of the 'isotopic trophic niches' and the range of resources used by Oribatida in the tropical forest to those observed in temperate forests. The range of trophic levels occupied by oribatid mites, as reflected in their nitrogen isotopic compositions, did not differ between tropical and temperate forests. In contrast, the range of δ¹³C values of oribatid mites in the tropical community was smaller than that typically observed in temperate forests. This was due to the lack of ¹³C-enriched species with strongly calcified integuments. The diversity of trophic niches and the range of resources consumed did not differ between temperate and tropical communities of Oribatida. Moreover, similar δ¹⁵N values were observed for oribatid mite families across temperate and tropical ecosystems, suggesting that the taxonomic system of soil- and litter-dwelling Oribatida is ecologically consistent and supporting the 'taxonomic sufficiency' principle.

Wolbachia of phylogenetic supergroup E identified in oribatid mite Gustavia microcephala (Acari: Oribatida)

Heritable endosymbionts have been observed in arthropod and nematode hosts. The most-known among them is Wolbachia. Although the bacterium was previously identified in oribatid mites (Acari: Oribatida), it was not assigned to any phylogenetic group. Endosymbionts have a profound influence on their hosts, playing various functions that affect invertebrate's biology such as changing the way of reproduction. Oribatida provide the very unique examples of groups in which even whole families appear to be thelytokous, so we considered that it is worth to investigate the occurrence of endosymbiotic microorganisms in oribatid mites, especially that the knowledge on the symbionts occurrence in this invertebrate group is negligible. We report for the first time Wolbachia in oribatid mite Gustavia microcephala. The sequences of 16S rDNA, gltA, and ftsZ genes of the endosymbiont from the mite showed the highest similarity to Wolbachia found in Collembola. Phylogenetic analysis based on single gene and concatenated alignments of three genes revealed that the bacteria from G. microcephala and Collembola were related and clustered together with supergroup E. Relatively close relationship of Wolbachia from oribatid and collembolan hosts might mean at the evolutionary scale that horizontal transfer of bacteria between these two groups of invertebrates may take place.

Phylogenetic analysis based on the 16S rDNA, gltA, gatB, and hcpA gene sequences of Wolbachia from the novel host Ceratozetes thienemanni (Acari: Oribatida)

We determined the occurrence of intracellular endosymbionts (Wolbachia, Cardinium, Arsenophonus, Rickettsia, Spiroplasma, Hamiltonella, flavobacteria, and microsporidia) in oribatid mites (Acari: Oribatida) with the use of PCR technique. For the first time we looked for and detected Wolbachia in parthenogenetic oribatid mite Ceratozetes thienemanni Willmann, 1943. The 16S rDNA, gatB, hcpA, and gltA sequences of Wolbachia in C. thienemanni showed the highest similarity (≥ 90%) to the genes of Wolbachia from springtails (Collembola) and oribatid mite Gustavia microcephala. We found the unique sequence 5'-GGGGTAATGGCC-3' in 16S rDNA of Wolbachia from C. thienemanni and collembolan representing group E. The phylogeny of Wolbachia based on the analysis of single genes as well as concatenated alignments of four bacterial loci showed that the bacteria from C. thienemanni belonged to Wolbachia group E, like the endosymbionts from springtail hosts and G. microcephala. Considering coexisting of representatives of Oribatida and Collembola in the same soil habitat and similar food, it is possible that the source of Wolbachia infection was the same. Residues of dead invertebrates could be in organic matter of their soil food, so the scenario of infection transferred by eating of remains of soil cohabitates is also possible. It could explain the similarity and relationship of the Wolbachia in these two arthropod groups. Oribatid mite C. thienemanni is a parthenogenetic mite which is a unique feature in the genus Ceratozetes. Moreover, this species, within the entire genus Ceratozetes, is characterized by the most northerly distribution. It is difficult to determine either it is parthenogenesis or the presence of endosymbionts that are in some way responsible for this kind of evolutionary success. Maybe we are dealing here with a kind of synergy of both factors?

A new Cardinium group of bacteria found in Achipteria coleoptrata (Acari: Oribatida)

The understanding of the biology of arthropods requires an understanding of their bacterial associates. We determined the distribution of bacteria Wolbachia sp., Rickettsia sp., Cardinium sp., Spiroplasma sp., Arsenophonus sp., Hamiltonella sp., and Flavobacterium in oribatid mites (Acari: Oribatida). We identified Cardinium sp. in Achipteria coleoptrata. This is the first report of this bacterium in A. coleoptrata. Approximately 30% of the mite population was infected by Cardinium sp. The Cardinium 16S rDNA was examined for the presence of two sequences unique for this microorganism. One of them was noted in Cardinium sp. of A. coleoptrata. In the second sequence, we found nucleotide substitution in the 7th position: A instead of T. In our opinion, this demonstrated the unique nature of Cardinium sp. of A. coleoptrata. We also determined phylogenetic relationship between Cardinium sp., including the strain found in A. coleoptrata by studying the 16S rRNA and gyrB gene sequences. It revealed that Cardinium from A. coleoptrata did not cluster together with strains from groups A, B, C or D, and constituted a separate clade E. These observations make A. coleoptrata a unique Cardinium host in terms of the distinction of the strain.

Seasonal fluctuation of oribatid mite communities in forest microhabitats

Oribatid mites are abundant and diverse decomposers in almost all terrestrial microhabitats, especially in temperate forests. Although their functional importance in the decomposition system in these forests has been investigated, spatio-temporal patterns of oribatid mite communities inhabiting different microhabitats have largely been neglected. Therefore, we (i) investigated seasonal fluctuation (monthly over one year) in oribatid-mite community structure and specificity to three microhabitats (moss, dead wood and litter) and (ii) analyzed the influence of air temperature and overall air humidity on seasonal community changes. In total, 57,398 adult oribatid mite individuals were collected. Total abundance, species richness and diversity differed among microhabitats. Seasonal changes were most pronounced in moss and least in litter. While overall air humidity had no influence on species distribution and community changes, air temperature positively influenced species richness and diversity, again most pronounced in moss. The calculated environmental temperature occurrence niche showed that 35% of adult oribatid mite species occurred at higher air temperatures. Furthermore, interaction/bipartite networks were more generalized-i.e., species were more equally distributed among moss, dead wood and litter-when ambient air temperatures were higher. This pattern is probably due to the dispersal ability of adult oribatid mites, i.e., species enter a dispersal mode only at higher air temperatures.

Taxonomic resolution and functional traits in the analysis of tropical oribatid mite assemblages

We analysed species-level datasets representing Oribatida assemblages along a gradient of old-growth primary tropical forests, secondary forests, and plantation forests in Dong Nai Biosphere Reserve, Vietnam. We identified patterns in abundance, species richness and species assemblages of Oribatida, then applied taxonomic sufficiency approach to the datasets. Using three levels of higher-taxon aggregation, we evaluated whether aggregated datasets are useful in identifying ecological patterns, in comparison to species-level data. Species-level data on Oribatida assemblages clearly separated plantation forests from other forest environments; there was no significant separation between primary and secondary forests. Geographical structuring of species-level assemblages was significant, separating sites from two regions of the reserve. There was a significant concordance between multivariate ordination plots produced for species-level and aggregated (families, suborders/superfamilies) datasets, with Oribatida assemblages of plantation forests consistently separated from two other forest types. Mycobatidae (at family level) and Ceratozetoidea (at suborder/superfamily level) were indicators of plantation forests. The coarsest taxonomic resolution dataset with only four aggregated groups produced no separation of Oribatida assemblages by forest type or region. Moderate level of taxonomic aggregation applied to Oribatida community data did not cause great differences in patterns revealed by multivariate analysis, and therefore could be a valid approach to analysing the structure of tropical Oribatida assemblages. The taxonomic level of suborders and Brachypylina superfamilies appears to be the best compromise for ecological information and ease of identification. Two traits-body size and reproductive mode-were recorded for collected Oribatida species. Community-weighted mean trait value, modified Mason's index of functional divergence, and Rao's index of functional diversity were calculated for each trait in each of the sampled Oribatida assemblages. Sexual reproduction was a dominant reproductive mode in soil Oribatida and did not vary across forest types, indicating similar levels of resource limitation for this trait. For body size, lower functional divergence in plantation forests suggests less scope for niche differentiation and higher competition among different body sizes in this forest type. Use of functional traits can enhance and complement the analysis of Oribatida communities, but more data are needed on feeding- and diet-related traits in tropical Oribatida.

(Acari, Oribatida, Lohmanniidae)

In this paper we describe two new species belonging to the family Lohmanniidae: Mixacarus turialbaiensissp. n. and Paulianacarus costaricensissp. n. from Costa Rica.

Storage and release of hydrogen cyanide in a chelicerate (Oribatula tibialis)

Cyanogenesis denotes a chemical defensive strategy where hydrogen cyanide (HCN, hydrocyanic or prussic acid) is produced, stored, and released toward an attacking enemy. The high toxicity and volatility of HCN requires both chemical stabilization for storage and prevention of accidental self-poisoning. The few known cyanogenic animals are exclusively mandibulate arthropods (certain myriapods and insects) that store HCN as cyanogenic glycosides, lipids, or cyanohydrins. Here, we show that cyanogenesis has also evolved in the speciose Chelicerata. The oribatid mite Oribatula tibialis uses the cyanogenic aromatic ester mandelonitrile hexanoate (MNH) for HCN storage, which degrades via two different pathways, both of which release HCN. MNH is emitted from exocrine opisthonotal oil glands, which are potent organs for chemical defense in most oribatid mites.

Toxicokinetics and time-variable toxicity of cadmium in Oppia nitens Koch (Acari: Oribatida)

The soil-living mite Oppia nitens Koch has recently been proposed as a promising test species for the ecotoxicological risk assessment of contaminated boreal soils. Adding oribatid mites to the assemblage of test species for soil is highly desirable given the enormous diversity and ecological significance of these microarthropods. The authors aimed at revealing how toxicity, lethal body concentration, and bioaccumulation of cadmium (Cd) changed over a period of 7 wk when mites were exposed to Cd-spiked natural soils. The estimated median lethal concentration (LC50) values showed a gradual decrease with time, but a steady state was not reached within 7 wk. Estimates for lethal body concentration varied from 44 μg Cd/g to 91 μg Cd/g dry body weight, with a tendency to increase with time. The estimated 50% effective concentration (EC50) for effects on reproduction after 7-wk exposure was 345 μg Cd/g dry soil. Accumulation of Cd in mites was extremely variable but overall showed a nonsaturating increase. A simple 1-compartment toxicokinetic model did not describe the data well. The analysis suggests that O. nitens has a storage-detoxification strategy that is not at equilibrium under chronic exposure. Considering the tiny body size of the animal, it is remarkable that long exposure times are necessary to reveal chronic toxicity. The use of oribatids provides a clear added value to soil risk assessment but trades off with exposure length. Environ Toxicol Chem 2017;36:408-413. © 2016 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Convergent evolution of aquatic life by sexual and parthenogenetic oribatid mites

Convergent evolution is one of the main drivers of traits and phenotypes in animals and plants. Here, we investigated the minimum number of independent colonisations of marine and freshwater habitats in derived oribatid mites (Brachypylina), a mainly terrestrial taxon. Furthermore, we investigated whether the reproductive mode (sexual vs. thelytokous) is associated with the habitat type (marine, freshwater) where the animals live. We hypothesized that continuous resource availability in freshwater systems fosters asexual reproduction. We used 18S rDNA sequences to construct a molecular phylogeny of oribatid mites from terrestrial, marine and freshwater habitats. The results indicate that aquatic life in oribatid mites evolved at least 3×: once in Limnozetoidea (including only freshwater taxa) and at least twice in Ameronothroidea. In Ameronothroidea the taxon Ameronothridae n. gen. (nr. Aquanothrus) colonized fresh water independently from Selenoribatidae and Fortuyniidae (mainly marine Ameronothroidea). Reproductive mode was associated neither with marine nor with freshwater life; rather, in both habitats sexual and parthenogenetic taxa occur. However, the reproductive mode was related to the stability of the habitat. Species that live underwater permanently tend to be parthenogenetic whereas taxa whose life cycle is often interrupted by flooding, such as marine oribatid mites, or by desiccation, e.g., freshwater-living Ameronothridae n. gen. (nr. Aquanothrus) (Ameronothroidea) species, are mainly sexual, indicating that continuous access to resources indeed favours parthenogenetic reproduction. Findings of our study therefore suggest that parthenogenetic reproduction is not selected for by disturbances but by unlimited access to resources.

Oribatid mite species numbers increase, densities decline and parthenogenetic species suffer during bog degradation

This study compared the oribatid mites in two natural and four industrially exploited bogs. One natural bog (Zakręt, Z) was located in northeastern Poland and the other one (Toporowy Staw Niżni, TSN), in southern Poland. The four exploited bogs were also located in southern Poland and can be ranked from least to most degraded as follows: Łysa Puścizna (LP), Baligówka (B), Puścizna Mała (PM) and Kaczmarka (K). In the natural bogs, the water pH was higher than in the degraded ones, but other parameters were lower (conductivity, colour value, oxygen demand, and concentration of chlorides). In the natural bogs, the Oribatida were highly abundant (average density was 169,100 ind./m(2)), but with low species diversity and one dominating species. In bog Z the most abundant was Limnozetes foveolatus that had dominance of 75 % and in bog TSN, located at higher altitude, Trimalaconothrus maior dominated (73 %). In two degraded bogs that had still good water conditions (LP and B) the oribatid communities resembled those from the natural bogs; in LP the most abundant species was Hydrozetes lacustris and in bog B, L. foveolatus. In contrast, in two more degraded bogs (PM and K) the abundance of mites was lower (average density was 17,850 ind./m(2)), species diversity of the Oribatida was higher, and no species achieved a high dominance like in the natural bogs. Additionally, in more degraded bogs the abundance of parthenogenetic species was lower than in the natural bogs.

Temporal fluctuations in oribatid mites indicate that density-independent factors favour parthenogenetic reproduction

We investigated the oribatid mite density, community structure and the percentage of parthenogenetic individuals in four different forest types across three regions in Germany in 2008 and once again in 2011. We compared temporal (inter-annual) fluctuations in population densities between sexually and parthenogenetically reproducing species of oribatid mites. We hypothesized that population densities in parthenogenetic oribatid mite species fluctuate more than in sexual ones. Further, we expected species composition and dominance of parthenogenetic species to differ between forest types and regions. Oribatid mite community structure did not differ between years but varied with forest type and region, indicating low species turnover in time. As hypothesized, temporal fluctuations were more pronounced in parthenogenetic as compared to sexual species. The percentage of parthenogenetic individuals was significantly higher in coniferous than in beech forests and significantly higher in Schorfheide-Chorin than in Hainich-Dün and Schwäbische Alb. The results indicate that parthenogenetic species flourish if populations are controlled by density-independent factors and dominate at sites were resources are plentiful and easily available, such as coniferous forests, and in regions with more acidic soils and thick organic layers, such as Schorfheide-Chorin. However, historical factors also may have contributed to the increased dominance of parthenogenetic species in the Schorfheide-Chorin, as this region was more heavily glaciated and this may have favoured parthenogenetic species. Overall, our study supports the hypothesis that parthenogenetic species benefit from the lack of density-dependent population control whereas the opposite is true for sexual species.

Biological properties of extremely acidic cyanide-laced mining waste

With respect to acidic, cyanide-laced tailings, the data about in situ toxicity and biological activity in highly polluted environment are often lacking. The aim of this study was to assess the microbial characteristics, composition of oribatid mite species, and level of genotoxic impact on plants in the area of inactive tailings pond (Horná Ves, Kremnica region). Sampling of the tailings, soils and selected plant species was carried out in spring of 2012. Trace element analysis (inductively coupled plasma emission and mass spectrometry) showed that concentration of Pb, Zn, and Cu in the tailings is approximately in thousands of ppm (mg kg(-1)). Amount of lead exceeded 16,000 mg kg(-1), which is perceived as the biggest threat with respect to possible toxicity. The risk is accentuated by extremely acidic pH of the tailings material which approached 2. In such conditions great mobility of (divalent) heavy metal cations is expected. The total cyanide concentration in the tailings was 472 mg kg(-1). Results of performed tests and measurements suggest that microbial activity at the tailings site (and its close environment) is hampered markedly. In the sludge material we detected low abundance of soil bacteria (2.08 × 10(4) CFU) and predominance of slowly growing K-strategists. On the other hand, the content of microbial C in the sludge sample was not too low, considering its extreme acidity and high amount of risk elements. In the same sample, just one mite species, Oppiella (O.) uliginosa (Willmann 1919), was identified. Also in case of the dam site the abundance of mites was considerably lower in comparison to reference sample. Values of Oribatida abundance were in positive correlation with values of microbial biomass carbon. Results of the pollen grain abortivity test, applied in situ on chosen plant species, indicated substantial presence of genotoxicity in the environment. Total induction index of tailings pond reached 3.59(±2.4) which expresses also total load of locality, comparing to natural biotope. In case of the technogenic sediment, the value was more than three times higher.

Phylogenetic relationships between Malgasodes, Bovicarabodes, Afticarabodes, Congocepheus and Cavaecarabodes are discussed

The genus Malgasodes is redefined; the type species M. curvisetus Mahunka, 2000, is redescribed by means of studies using optic and Scanning Electron Microsopy (SEM), and a complementary description of M. hungarorum Mahunka, 2000 is included. Comparison of genera Malgasodes Mahunka, 2000, Bovicarabodes Fernandez, Theron, Rollard, 2013a, Cavaecarabodes Fernandez, Theron, Rollard, Rodriguez Castillo, 2014, Afticarabodes Fernandez, Theron, Rollard, 2013b, and Congocepheus Balogh, 1958 is made. Problems concerning chaetotaxy, regressive evolution and neotrichy are explained and phylogenetic relationships between Malgasodes, Bovicarabodes, Afticarabodes, Congocepheus and Cavaecarabodes are discussed.

Umashtanchaeviella plethotricha, a new genus and species of the family Tetracondylidae (Acari, Oribatida)

A new genus of oribatid mites of the family Tetracondylidae, Umashtanchaeviella gen. n., with type species Umashtanchaeviella plethotricha sp. n., is proposed and described from forest litter, the Bu Gia Map National Park, southern Vietnam. The new genus is distinguishable from other otocepheoid genera by the presence of notogastral plethotrichy.

Two new species of oribatid mites of the family Galumnidae (Acari, Oribatida) from Vietnam

Two new species of oribatid mites of the family Galumnidae, Allogalumna monodactyla sp. n. and Galumna (Galumna) paracalcicola sp. n., are described from dark loamy soil under crown of Ficus sp. in southern Vietnam. Allogalumna monodactyla sp. n. is the first identified member of Allogalumna recorded for Vietnam. The identification keys to the species of Allogalumna from the Oriental region and species of Galumna (Galumna) from Vietnam and the calcicola-group are given.

Morphology of adult and juvenile instars of Galumna obvia (Acari, Oribatida, Galumnidae), with discussion of its taxonomic status

The adult instar of the oribatid mite, Galumna obvia (Berlese, 1914), is redescribed in detail, on the basis of specimens from Finland. The morphology of juvenile instars of G. obvia is described and illustrated for the first time, and compared to that of other species of the family Galumnidae. The position of the insertion of the lamellar seta in adults proved variable in studied European populations, being either on or medial to the lamellar line. Since the genera Galumna and Pergalumna are currently distinguished only by the relative positions of the seta and line, specimens of G. obvia in some populations show an intermediate situation between other studied Galumna species – with lamellar seta on or lateral of lamellar line – and Pergalumna with lamellar seta at a distinct distance medially of lamellar line. A detailed reevaluation of the two genera is needed.

New and little known species of oribatid mites of the family Haplozetidae (Acari, Oribatida) from Ecuador

We described two new species, Haplozetes paraminimicoma sp. n. and Protoribates ecuadoriensis sp. n. from Ecuador. Additionally, a detailed supplementary description of Trachyoribates (Rostrozetes) glaber (Beck, 1965) is given on the basis of Ecuadorian specimens, which was known previously only from Peru. An annotated checklist of all identified taxa of Haplozetidae from Ecuador is presented.

Oribatida (Acari) in grassy arable fallows are more affected by soil properties than habitat age and plant species

Oribatid mites are one of the numerically dominant arthropod groups in soils. They play an important role in soil food webs via regulating the decomposition of organic matter and propagating microorganisms within the soil. To our knowledge, the influence of different plant functional groups on oribatid mites has not been studied in abandoned farmland with undisturbed succession before. The density and assemblage structure of oribatid mites in nine grassy arable fallows relative to three habitat age classes (2-3, 6-8, 12-15 years) and three selected plant species (legume: Medicago sativa, forb: Taraxacum officinale, grass: Bromus sterilis) were investigated in soil associated with single plants. Mite density declined marginally not significant with habitat age because of high abundances of the ubiquitous species Tectocepheus velatus sarekensis and Punctoribates punctum in young and mid-aged fallows and their subsequent decline in old fallows. Oribatid mite density and species assemblage were not affected by plant species. Only P. punctum had significantly higher densities in B. sterilis samples than in T. officinale samples due to a higher amount of fine roots. Distance-based linear models revealed that 65% of the variation in mite assemblage was explained by soil properties, soil type, exposition and geographic position, while habitat age was of minor importance. Canonical correspondence analysis revealed that the mite assemblage was best explained by soil organic and microbial carbon, water content and pH.

Oribatid mites (Acari, Oribatida) from riverine environments of some islands in Oceania

A checklist of identified oribatid mite taxa from riverine freshwater environments from six islands in Polynesia (New Caledonia, Tahiti, Moorea, Rurutu, Tubuai, Raiatea) is presented; 18 species, 16 genera and eight families were recorded. Trhypochthoniellus longisetus (Berlese, 1904) and Trimalaconothrus albulus Hammer, 1972 prevailed on distribution. Fortuynia smiti sp. n. (Fortuyniidae) is described from New Caledonia. The new speciesis morphologically most similar to Fortuynia marina Hammen, 1960 from New Guinea, but it differs from the latter by the longer notogastral setae dm, lm, c 2, p 1, epimeral setae 3b and adanal setae ad 1 and the presence of prodorsal lateral ridges.

The soil mite genus Conchogneta (Acari, Oribatida, Autognetidae), with new findings from Mongolia

This work deals with taxonomy, geographical distribution as well as known ecology of oribatid mites of the genus Conchogneta Grandjean, 1963 in the world. The majority of species belonging to this genus is known to be widely distributed in Europe, but only three of them are found in other areas of the northern hemisphere. Most species of Conchogneta are inhabitants of litter of various types of forestas, terricolous and epiphytic bryophytes, epiphytic lichens, and soil of steppe, river valleys, moor, oligotrophic bogs, floodland assemblages etc. A new species, Conchogneta glabrisensillatasp. n. is described, and another species, Conchogneta traegardhi (Forsslund, 1947) is redescribed from the northern and western parts of Mongolia, respectively. Conchogneta is recorded for the first time for the fauna of Mongolia. The species status of Conchogneta dalecarlica (Forsslund, 1947) is discussed. Species descriptions are accompanied with detailed illustrations. Furthermore, a key is provided for the identification of adults of the known species of Conchogneta in the world.

First record of the subgenus Damaeus (Paradamaeus) Bulanova-Zachvatkina (Oribatida, Damaeidae) from China, with description of a new species

A new species Damaeus (Paradamaeus) yushuensissp. n. is described from Three Rivers’ Headwaters National Natural Reserve, Qinghai province, China. This is the first record of this subgenus in China. A key is given to distinguish all species of the genus.