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Species of the genus Oromurcia Thor, 1930 (Oribatida, Ceratozetidae) mainly have an arctic or alpine distribution in the Western Palaearctic region and Greenland. We describe a new species of Oromurcia from Northeast Asia (Magadan Region, Russia) based on adult and juvenile instars. Numerous populations of Oromurcia magadanensis sp. nov. were found under arctic-alpine plants in a narrow stream gully with large snow accumulation on the Ola Plateau (1023 m a.s.l.). Adults of Oromurcia magadanensis sp. nov. differ from those of Oromurcia bicuspidata and O. sudetica by their smaller size, the presence of clavate, distally broadly rounded bothridial seta, tutorium with several teeth distally, and the absence of striations on the lamella. Juvenile instars of the new species differ from those of O. bicuspidata and O. sudetica by the presence of medium-sized gastronotic setae in the larva, and long lateral and posterior gastronotic setae in nymphs. We compare adult and juveniles of Oromurcia magadanensis sp. nov. with those of other members of the ceratozetid subfamily Trichoribatinae Shaldybina, 1966 from arctic or alpine regions, for which ontogeny is known, and provide revised diagnoses for adult and juvenile members of Trichoribatinae. All Oromurcia species are associated with cold wet places (periglacial habitats, bogs and fens, alpine meadows, snowbeds, and, less frequently, montane coniferous forests) in Eastern and Western Palaearctic, but they are absent from High Arctic and Siberian regions that are ultra-cold in winter. This spatial disjunction argues for a former Trans-Palaearctic range that was possibly subdivided by reсurrent cryo-arid Pleistocene episodes.

For decades, two very similar Arctic oribatid mite species in the family Ceratozetidae—Oromurcia lucens (L. Koch, 1879) and Svalbardia paludicola Thor, 1930—were considered independent taxa and were often confused in the literature. Based on morphological analysis of specimens from the type localities, as well as extensive material from different Arctic regions, we make the following taxonomic proposals: Svalbardia lucens (L. Koch, 1879) comb. nov. (=Svalbardia paludicola Thor, 1930 syn. nov.). Furthermore, we propose that the subfossil Svalbardia rostralis Druk, 1982 (in Kiselev et al. 1982) is a junior subjective synonym (syn. nov.) of S. lucens. We summarize data on distribution and habitat preferences of S. lucens in the Arctic. The frequent occurrence of S. lucens in Pleistocene deposits and its strong dependence on moisture make this species a reliable “type fossil” in paleoclimatic reconstructions.

A new oribatid mite genus, Hogsbackia gen. nov. (Oribatida, Punctoribatidae), with type species Hogsbackia africaensis sp. nov., is proposed and described from the indigenous Afromontane forest of South Africa. The new genus is closely related to Scotiazetes, from which it is most easily distinguished by body size ratio, number of notogastral and genital setae, type of humeral porose area Ah, position of dorsophragmata, and leg setation. The redescription of Scotiazetes bidens Wallwork, 1966 is presented, based on material from South Georgia (Antarctic region). The generic diagnosis of Scotiazetes is revised, and the genus is transferred from Ceratozetidae to Punctoribatidae. Relationships between the genera Hogsbackia gen. nov., Scotiazetes and other punctoribatid genera are discussed.

A new oribatid mite genus, Sculpteremaeus gen. nov. (Oribatida, Cymbaeremaeidae), with Sculpteremaeus olszanowskii sp. nov. as type species, is proposed and described based on adults. It is from sandy soil-litter in chaparral of California, USA, an environment from which no oribatid mites have been recorded previously. Based on an analysis of adults of all genera of Cymbaeremaeidae, the new genus is closely related to Ametroproctus, from which it is most easily distinguished by the morphology of lamellae, size of lamellar cusps, and shape of the tutorium. We expand the Cymbaeremaeidae family diagnosis, and question the inclusion of Scapheremaeus based on extensive molecular evidence showing its closer relationship with Ameronothroidea and Licneremaeoidea.

Canadian Cretaceous amber belongs to the Taber Coal Zone, and was deposited in beds of coal and shale saturated with organic matter. It is upper Campanian (~76–72 million years ago), and the source of the original resin is predominantly the plant genus Parataxodium Arnold and Lowther (Cupressaceae). We describe the first oribatid mite from this amber, Megeremaeus cretaceousnew species (Acari: Oribatida: Megeremaeidae). We provide a key to all described species of Megeremaeus Higgins and Woolley, 1965, and discuss the advantages that confocal microscopy provides for the study of dark, resin-filled, miniature amber inclusions.

This checklist of the oribatid fauna of Canada and Alaska (excluding Astigmata) includes 580 identified species in 249 genera and 96 families. The known fauna of Canada includes 556 identified species in 247 genera, and that of Alaska includes 182 species in 95 genera; 39 of the 42 oribatid superfamilies are represented. We further list ~ 300 species that are currently unidentified, and possibly undescribed. In addition, we list 42 genera that are represented only by unidentified and probably undescribed species. For each species we give combinations and synonymies, specific locations in Alaska and the Provinces and Territories of Canada, habitats, and biogeography. There are 182 identified species known for Alaska, 152 for Yukon, 122 for Northwest Territories, 58 for Nunavut; 210 for British Columbia, 213 for Alberta, 15 for Saskatchewan, 84 for Manitoba, 167 for Ontario, 210 for Québec, 110 for Nova Scotia, 77 for New Brunswick, 84 for Newfoundland and 6 for Prince Edward Island. The known fauna of Canada is smaller than that of Austria, and is approximately equivalent to that of the Czech Republic. As these countries are much smaller in size than Canada and less ecologically diverse, we consider the Canadian and Alaskan fauna are at most 25% known. The paucity of these data reflects the absence of taxonomic and faunistic studies on Oribatida in State, Provinces or Territories, and especially in the Canadian and Alaskan National Park systems and the hundreds of Provincial Parks. Despite the almost 90% increase in described species since the catalogue of Marshall et al. (1987), there is a need for focussed, coordinated research on Oribatida in the natural regions throughout Canada and Alaska, and for monographs on families and genera with large numbers of undescribed species, such as Brachychthoniidae, Damaeidae, Cepheidae, Liacaridae, Oppiidae, Suctobelbidae, Hydrozetidae, Phenopelopidae, Scheloribatidae, Haplozetidae and Galumnidae.

Soils host the vast majority of life on Earth including microorganisms and animals, and supporting all terrestrial vegetation. While soil organisms are pivotal for ecosystem functioning, the assemblages of different biota from a taxonomic and functional perspective, as well as how these different organisms interact, remains poorly known. We provide a brief overview of the taxonomic and functional diversity of all major groups of soil biota across different scales and organism sizes, ranging from viruses to prokaryotes and eukaryotes. This reveals knowledge gaps in relation to all soil biodiversity groups, which are especially evident for viruses, protists, micro- and meso-fauna. We review currently-available methods to study the taxonomic and functional diversity of soil organisms by grouping all commonly-used methods into morphological, biochemical and molecular approaches. We list potentials and limitations of the methods to reveal that there is, as yet, no single method to fully characterize the biodiversity even of a single group of soil biota. Yet, we stress that we now have the methods available to enable scientists to disentangle the taxonomic and functional diversity of virtually all soil organisms. We provide a user-friendly guide to help researchers address a wider variety of soil biodiversity in their studies by discussing and critically analysing the various potentials and limitations of diverse methods to study distinct groups of soil life. We highlight that integrative methodological approaches, ideally in collaborative interactions, are key to advancing our understanding of soil biodiversity, such as the combination of morphological and molecular approaches to overcome method-specific limitations. Together, integrative efforts can provide information on the abundance, biomass, diversity and function of several groups of soil biota simultaneously. This newly-obtained integrative information on soil biodiversity will help to define the importance of soil biodiversity in ecosystem processes, functions, and services, and serve to refine food-web and earth system models.

Species of the oribatid mite genus Trichoribates (Oribatida, Ceratozetidae) are primarily north temperate in distribution, with only two species known from the Neotropics. We describe Trichoribates sidorchukae sp. nov. from the tropical montane of Ecuador, based on adult morphology, the first species in the genus from Ecuador. We provide a revised generic diagnosis to include character states overlooked in previous diagnoses. An identification key to known species of Trichoribates in the Neotropical region is provided.

Summaries of taxonomic knowledge are provided for all acarine groups in Canada, accompanied by references to relevant publications, changes in classification at the family level since 1979, and notes on biology relevant to estimating their diversity. Nearly 3000 described species from 269 families are recorded in the country, representing a 56% increase from the 1917 species reported by Lindquist et al. (1979). An additional 42 families are known from Canada only from material identified to family- or genus-level. Of the total 311 families known in Canada, 69 are newly recorded since 1979, excluding apparent new records due solely to classification changes. This substantial progress is most evident in Oribatida and Hydrachnidia, for which many regional checklists and family-level revisions have been published. Except for recent taxonomic leaps in a few other groups, particularly of symbiotic mites (Astigmata: feather mites; Mesostigmata: Rhinonyssidae), knowledge remains limited for most other taxa, for which most species records are unpublished and may require verification. Taxonomic revisions are greatly needed for a large majority of families in Canada. Based in part on species recorded in adjacent areas of the USA and on hosts known to be present here, we conservatively estimate that nearly 10,000 species of mites occur in Canada, but the actual number could be 15,000 or more. This means that at least 70% of Canada’s mite fauna is yet unrecorded. Much work also remains to match existing molecular data with species names, as less than 10% of the ~7500 Barcode Index Numbers for Canadian mites in the Barcode of Life Database are associated with named species. Understudied hosts and terrestrial and aquatic habitats require investigation across Canada to uncover new species and to clarify geographic and ecological distributions of known species.

A new oribatid mite species of the genus Nesozetes (Oribatida, Nesozetidae) is described from moss (Sphagnum sp.) on the seepage area below a permanent spring in South Africa. Nesozetes membranus sp. nov. differs from its only congener, Nesozetes rostropterus, described from Fiji, by the presence of a second pair of membranes located in the podosomal region, setiform bothridial setae and striate subcapitular mentum. A revised diagnosis of Nesozetidae, discussion on its taxonomic status, and information on distribution and ecology of Nesozetes species are given.

A new species of Antarctozetes (Oribatida, Ceratozetoidea) is described from the soil in New Zealand based on adult morphology. Antarctozetes mariehammerae sp. nov. differs from Antarctozetes intermedius (Hammer, 1967) by the short rostral setae, very short stalks of bothridial setae, and bidentate lamellar cusps. A revised generic diagnosis is given, Antarctozetes is maintained in Punctoribatidae, although knowledge of juvenile instars is lacking. The relationship of Antarctozetes , Anellozetes, Africoribates and Kilimabates is discussed. Data on habitat and an identification key to known species of Antarctozetes in New Zealand are provided.

Soil inhabiting oribatid mites (Acari: Oribatida) are one of the most interesting groups of animals because of their ecological characteristics at the community level. However, existing knowledge does not provide comprehensive explanations of the mechanisms underlying their community or metacommunity structure. The aim of this study is to investigate peat bog inhabiting oribatid mite metacommunity distribution throughout the Holarctic region. Species incidence data was collected (mainly from published sources) for 46 peat bog localities, comprising a total of 410 species. Characteristics of species composition (coherence, turnover and boundary clumping) were analyzed to reveal patterns of peat bog oribatid metacommunity for different ecological guilds. We also applied correlation and regression analysis to detect whether peat bog oribatid communities show latitudinal gradient and distance decay in compositional similarity. Analysis of metacommunity structure showed non-random structure for all ecological guilds studied with dominating nested and Clementsian patterns. No significant evidence was found for latitudinal gradients in species composition whereas non-linear distance decay in compositional similarity is a common phenomenon for peat bog oribatid communities. We discuss these metacommunity patterns within the framework of existing hypotheses and conclude that the community level structure for peat bog oribatid species is largely determined by interspecific interactions and common biogeographical history, whereas metacommunity patterns are the result of postglacial colonization processes.

A new species of oribatid mite of the genus Striatoppia is described on the basis of adult specimens from natural and urban habitats in Tbilisi, Georgia, the first record of the genus for the western Palaearctic. Based on character states of this species, arguments are presented for Striatoppia being a possible member of the Autognetidae.

We propose a new species of oribatid mite, Unduloribates dianae sp. nov., based on material collected from a variety of boreal habitats in the Canadian Provinces Newfoundland, Nova Scotia, Québec, Alberta and British Columbia, and in New York State in the USA. This is the first species in this genus from the Nearctic. Description is based on adults and all immature stages. We present an expanded generic diagnosis and a key to world species of Unduloribates, and argue for the retention of Unduloribatidae as a monogeneric family in Phenopelopoidea.

The oribatid mite genusCeratozetesBerlese is represented in America north of Mexico by 21 previously described species known from forest, grassland, subarctic and arctic soils and litter, and canopy habitats. The closely related genusCeratozetoidesShaldybina is represented in America north of Mexico only byC. cisalpinus(Berlese). Three new species ofCeratozetesfrom North America are described:C. biporosussp. nov.from forest habitats of southeastern North America,C. cyclopeasp. nov.from montane habitats in western North America, andC. pseudomediocrissp. nov.from forest habitats of western North America. A detailed revised diagnosis is given forCeratozetes,Ceratozetoides, all previously described species ofCeratozetes(C. angustus(Banks),C. borealisBehan-Pelletier,C. cuspidatusJacot,C. enodis(Ewing),C. fjellbergiBehan-Pelletier,C. gracilisMichael,C. kutchinBehan-Pelletier,C. longispinusJacot,C. mediocris(Berlese),C. oresbiosBehan-Pelletier,C. pacificusBehan-Pelletier,C. parvulusSellnick,C. spitsbergensisThor,C. subaquila(Ewing),C. subinconspicuus(Berlese),C. thienemanniWillmann,C. virginicus(Banks), andC. watertonensisBehan-Pelletier), andCeratozetoides cisalpinus.Ceratozetes figuratus(Ewing) andC. zeteki(Ewing) are considered junior subjective synonyms ofC. enodis(Ewing)syn. nov., andC. inupiaqBehan-Pelletier is transferred to Mycobatidae asCyrtozetes inupiaq(Behan-Pelletier)comb. nov. New distribution records are given forCeratozetoides cisalpinusandCeratozetes angustus,C. borealis,C. cuspidatus,C. gracilis,C. mediocris,C. longispinus,C. oresbios,C. pacificus,C. parvulus,C. thienemanni,C. virginicus, andC. watertonensis.A diagnostic key is provided to adults of theCeratozetesandCeratozetoidesspecies now known for America north of Mexico. An analysis of the systematic relationships of 23 of these species based on adult characters indicates thatCeratozetes, excludingCeratozetoides, is paraphyletic. The clade that includesCeratozetoides cisalpinusand 15 species ofCeratozetesincludes most species for which immatures are known. One sister clade includesCeratozetes cyclopea,C. enodis, andC. fjellbergiand another includesC. kutchin, C. parvulus, andC. thienemanni.The decision whether or not these 6 species should be retained inCeratozetessensu strictoawaits discovery of their immatures and molecular analysis.

We present the systematics and ecology of a new species of arboreal oribatid mite in the family Achipteriidae, Anachipteria geminussp. nov., a dominant arthropod in canopy lichens associated with western hemlock (Tsuga heterophylla (Raf.) Sarg. (Pinaceae)) and Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Dougl. ex Forbes (Pinaceae)) in the coniferous temperate and montane forests of the Pacific Northwest of North America. The species is described on the basis of the morphology of all active instars plus molecular sequence data for the D3 region of the 28s rRNA (D3-28s) and mitochondrial cytochrome oxidase 1 (CO1) genes. Anachipteria geminus is the dominant oribatid mite in foliose lichens in the upper canopies of Pacific montane conifer trees. Specimens were found in 100% of canopy lichens sampled, and abundances can reach 1450 individuals / 100 g dry mass of lichen. Analysis of the population structure indicates that A. geminus has seasonally stable populations consistent with overlapping generations. Anachipteria geminus expresses morphological character states that require expanding the diagnoses of the genus Anachipteria and the family Achipteriidae. A revised diagnosis and morphological key to species of Anachipteria in Canada are given.

Climate and litter quality are primary drivers of terrestrial decomposition and, based on evidence from multisite experiments at regional and global scales, are universally factored into global decomposition models. In contrast, soil animals are considered key regulators of decomposition at local scales but their role at larger scales is unresolved. Soil animals are consequently excluded from global models of organic mineralization processes. Incomplete assessment of the roles of soil animals stems from the difficulties of manipulating invertebrate animals experimentally across large geographic gradients. This is compounded by deficient or inconsistent taxonomy. We report a global decomposition experiment to assess the importance of soil animals in C mineralization, in which a common grass litter substrate was exposed to natural decomposition in either control or reduced animal treatments across 30 sites distributed from 43°S to 68°N on six continents. Animals in the mesofaunal size range were recovered from the litter by Tullgren extraction and identified to common specifications, mostly at the ordinal level. The design of the trials enabled faunal contribution to be evaluated against abiotic parameters between sites. Soil animals increase decomposition rates in temperate and wet tropical climates, but have neutral effects where temperature or moisture constrain biological activity. Our findings highlight that faunal influences on decomposition are dependent on prevailing climatic conditions. We conclude that (1) inclusion of soil animals will improve the predictive capabilities of region- or biome-scale decomposition models, (2) soil animal influences on decomposition are important at the regional scale when attempting to predict global change scenarios, and (3) the statistical relationship between decomposition rates and climate, at the global scale, is robust against changes in soil faunal abundance and diversity.

To study the oribatid mite community inhabiting microhabitats in the canopy of montane Abies amabilis [(Douglas ex D. Don) Lindl.] and Tsuga heterophylla [(Raf.) Sarg] tree species across five elevational sites, we collected 180 branch tips and 180 foliose/crustose lichen samples over three time periods. Thirty-three species of oribatid mites were identified from the study area. Mite species richness and abundance was significantly affected by microhabitat, and this association was independent of sampling time. At the microhabitat scale, distinct species assemblages were associated with lichen and branch tip habitats, and to a lesser degree, tree species. Conifer specificity was most apparent in the closely related species of Jugatala, where Jugatala tuberosa Ewing was only found on branch tips from A. amabilis and Jugatala sp. was primarily found on branch tips from T. heterophylla. Microhabitat specificity was most pronounced in Dendrozetes sp. where most individuals were found on branch tips and Anachiperia geminus Lindo et al. that occurred primarily on lichens. Principal components analysis of oribatid mite community composition further showed a high degree of association with microhabitat and tree species. Habitat profiles are difficult to discern for many species because tree, microhabitat, and elevation preferences confound distribution patterns. Given the significant tree-microhabitat associations in species composition in this montane canopy study, we suggest that sampling multiple microhabitats across elevations to look for patterns in community structure offers opportunities to explicitly test organizing principles in community ecology.

The oribatid mite family Mycobatidae is represented in America north of Mexico by the eight genera, Cyrtozetes Behan-Pelletier, Ceresella Pavlitshenko, Guatemalozetes Mahunka, Minunthozetes Hull, Mycobates Hull, Pelopsis Hall, Punctoribates Berlese, and Zachvatkinibates Shaldybina. Species occur in forests, grasslands, and arctic soils, in canopy habitats, and in the marine and freshwater littoral zone. Three new mycobatid species from North America are described: Ceresella reevesisp. nov. from forest habitats of western North America, Cyrtozetes lindoaesp. nov. from canopy habitats of western Canada, and Punctoribates weigmannisp. nov. from forest litter in eastern North America. The descriptions of Pelopsis bifurcatus (Ewing) and Punctoribates punctum (C.L. Koch) are expanded based on specimens from North America. Punctoribates palustris (Banks) is redescribed based on specimens from throughout North America. Punctoribates armipes (Banks) is considered a junior subjective synonym of P. palustris (Banks). New distribution records are given for Guatemalozetes danos Behan-Pelletier and Ryabinin and Minunthozetes semirufus (Koch). Diagnoses are given for each genus discussed, and keys are provided to the eight genera of Mycobatidae of North America and to species of Cyrtozetes and Punctoribates, genera not recently revised.

Oribatid mites are primarily terrestrial. Only about 90 species (less than 1% of all known oribatid species) from 10 genera are truly aquatic, with reproduction and all stages of their life cycle living in freshwater. Adaptation to aquatic conditions evolved independently in different taxa. However, many terrestrial species can also be found in aquatic habitats, either as chance stragglers from the surrounding habitats, or from periodic or unpredictable floodings, where they can survive for long periods. In spite of their low species richness aquatic oribatids can be very abundant in different freshwater habitats as in lentic (pools, lakes, water-filled microhabitats) or flowing waters (springs, rivers, streams), mainly on submerged plants. The heavily sclerotized exoskeletons of several species enables subfossil or fossil preservation in lakes or bog sediments.

We propose a new genus of licneremaeoid oribatid mite, Phylleremus, based on two new species collected from leaves of woody dicots in Queensland, New South Wales, Victoria and Tasmania, Australia. Description of the type species, Phylleremus leei n. sp., is based on adults and all active immature stages; that of Phylleremus hunti n. sp. is based on adults and tritonymphs. Phylleremus adults have the notogastral octotaxic system of dermal glands developed either as 1 or 4 pairs of saccules, and nymphs are bideficient and plicate. We discuss the characteristics and relationships of this genus to others in Licneremaeoidea and argue for an affiliation with Adhaesozetidae.

In North America, species diversity in the oribatid family Oribatellidae is primarily in the genus Oribatella Banks, but the genera Adoribatella Woolley, Ferolocella Grabowski, Joelia Oudemans and Ophidiotrichus Grandjean are also represented. I provide detailed diagnoses for these genera and the previously described species, Adoribatella punctata Woolley, known from Colorado and Oregon, USA, and Alberta, Canada, Ferolocella tessalata Berlese known from Missouri, Virginia, West Virginia, Georgia, Wisconsin, Ohio, Alabama, Arkansas and Texas, USA, and Ophidiotrichus exastus Woolley, known from North Carolina, Alabama, Missouri, Tennessee and Georgia, USA. I describe Joelia appalachia sp. nov., based on adult specimens, from West Virginia. A key is given to distinguish adults of these genera from those of Oribatella. Character states shared by adults of Oribatellidae are discussed, the synonymy of Gendzella Kuliev with Ferolocella is rejected, and arguments are presented for movement of Adoribatella from Oribatellidae to the Ceratozetoidea.

Species in the oribatid mite genus Autogneta are primarily Palaearctic, with a few, mainly unidentified records from North America. Strong sexual dimorphism is reported in the genus for the first time; it is expressed by a posterior porose region on the male notogaster that in some species is associated with modifications of notogastral setae hsub1/suband psub1/sub. Herein, I describe 3 new dimorphic Autogneta species from North America, based on adult specimens: A. aokii sp. nov. and A. schusteri sp. nov., from California, USA, and A. flaheyi sp. nov., from British Columbia and Alberta, Canada. New diagnoses for 2 other dimorphic species, the type species Autogneta longilamellata (Michael) and A. amnica Jacot, are presented that accommodate their previously unreported dimorphic males. Autogneta flumengalei Jacot is recombined as Conchogneta flumengalei (Jacot) comb. nov. Finally, I give a key to adults of Autogneta species known from North America.

The oribatid mite genusZachvatkinibates, found in littoral, forest canopy, and forest litter habitats, includes some species showing distinct sexual dimorphism in the octotaxic system of dermal glands, and others lacking this dimorphism. Three new species in this genus are described on the basis of adults, each of which shows species-specific sexual dimorphism:Z. nortonisp. nov.andZ. schatzisp. nov.from beach debris in British Columbia, Canada, andZ. shaldybinaesp. nov.from the littoral in eastern and northeastern Canada. We discuss the association of sexual dimorphism with the littoral habitat of species in this genus and, more generally, the expression of sexually dimorphic porose areas in Ceratozetoidea. We revise the diagnosis for the genusZachvatkinibatesand present a revised key for adults ofZachvatkinibatesspecies of North America north of Mexico.

Forest canopies support diverse assemblages of free-living mites. Recent studies suggest mite species complementarity between canopy and terrestrial soils is as high as 80–90%. However, confounding variation in habitat quality and resource patchiness between ground and canopy has not been controlled in previous comparative studies. We used experimental litter bags with standardized microhabitat structure and resource quality to contrast the colonization dynamics of 129 mite species utilizing needle accumulations on the ground vs in the canopy of Abies amabilis trees in a temperate montane forest in Canada. Mite abundance and species richness per litter bag were five to eight times greater on the ground than in the canopy, and composition differed markedly at family-, genus-, and species-level. Seventy-seven species (57%) were restricted to either ground or canopy litter bags, but many of these species were rare (n

Morphology, distribution, and habitat data are presented for three species of the oribatid mite genus Gymnodampia Jacot occurring in North America. A revised generic diagnosis is given and the type species Gymnodampia setata (Berlese) is redescribed based on topotypic material from Missouri. Immatures of G. setata are described and aspects of their biology are presented. Two new species from North America, G. jacotisp. nov. and G. lindquistisp. nov., are proposed and described on the basis of adults, and a key is given for North American species of Gymnodampia. The ameroid genera Cristamerus Hammer, from Pakistan and China, and Defectamerus Aoki, from Japan, Korea, and China, are considered junior synonyms of Gymnodampia, and G. conformis (Fujikawa) is considered a junior synonym of G. fusca (Fujikawa). Immatures of G. setata are apheredermous, but with a circular line of dehiscence, whereas known immatures of the superfamily Ameroidea are eupheredermous. Nonetheless, without convincing apomorphic traits linking Gymnodampia to any known apheredermous family of Brachypylina, we hypothesize that Gymnodampia has lost the eupheredermy characteristic of Ameroidea, and we place it in the family Ameridae on the basis of adult similarities.

In Canadian agricultural soils, mites (Acari) are the most diverse and abundant arthropods. In comparison with other arachnids, mites are notable for their small size, diverse feeding habits, often complex life histories, and the range of habitats in which they live. Collembola are also abundant and diverse in soil and litter, they are in the same size range as the Acari, and for that reason the two groups are often combined in soil ecological studies as “microarthropods ”. This paper provides a descriptive overview of the state of our knowledge on the taxonomy of these arthropods. It reviews the literature on biology and ecology of microarthropods in Canadian agroecosystems, especially on implications of various agricultural practices for their diversity and population structure. It discusses the research challenges in taxonomy and ecology to address effective use of this biodiversity in Canadian agroecosystems. Key words: Acari, Collembola, microarthropods, taxonomy, ecology

Summary Livestock grazing influences plant community structure, soil quality and health, and is likely to also affect the populations and diversity of soil biota. In our study, we determined the abundance and family level diversity of soil mites under very heavy and light grazing regimes, and a very heavy grazing exclosure, and asked whether there were differences in abundance of mite taxa that reflected the severity of disturbance. The field experiment we sampled was established in 1949 on a Rough Fescue Prairie with Orthic Black Chernozemic (Udic Haploboroll) soils near Stavely Alberta Canada. Soil cores were taken from the light (L)(1.2 AUM (animal unit month) ha –1 ) and very heavy (VH) (4.8 AUM ha –1 ) grazing regimes and the grazing recovery exclosure (Ex) in the very heavy grazing site in June and October 1999. The results showed that the soil temperature, moisture and bulk density varied between the grazing regimes, soil depth and the sampling times. Collembola were not abundant at any of the sites compared with Acari. Among Acari, prostigmatid mites were significantly more abundant in VH site and all the grazing treatments at both depths and sampling times. Oribatida, and to a lesser extent Mesostigmata, were more closely associated with reduced and undisturbed habitats than the Prostigmata, and there was a positive relationship between increased grassland productivity and the abundance and diversity of soil microarthropods. Our results suggest that Acari are sensitive to soil disturbance.

INCO Ltd. near Sudbury, Ontario is rehabilitating nickel- and copper-mine tailings using vegetating techniques that have resulted in habitats of varying age and complexity. Mite (Acari) communities and soil quality characteristics were used to evaluate soil ecosystem development on four tailings sites, 0, 8, 20 and 40 years post rehabilitation in comparison with that on four control sites. Abundance, species richness, diversity (H′) and community structure of soil mites were sensitive indicators of tailings rehabilitation and soil formation. Mite density on older and botanically diverse tailings sites was comparable to that on control sites; however, species richness of oribatids and mesostigmatics was lower than on control sites. Mite species richness and diversity on tailings were lower at less botanically diverse sites regardless of age. Similarity of tailings-mite communities to control-site communities generally increased with age; however, similarities were all less than 60% (Sorenson's quantitative index, CN). Mite assemblages on tailings were dominated by a few colonizing species, whereas control sites had a diverse assemblage of species. Soil pH and organic matter (SOM) of rehabilitated tailings improved with age and degree of botanical complexity. Mite density and diversity was positively related to SOM particularily for the Oribatida. SOM and mites were mainly restricted to the 0–5-cm horizon.

The oribatid mite family Tegoribatidae has been represented in continental North America by the genera Tegoribates and Tectoribates. Herein, I describe a new genus of Tegoribatidae from North America, Protectoribates, and two new species: Protectoribates occidentalis sp. nov., from forest habitats in western North American, and Tegoribates walteri sp. nov., from forest habitats in California, based on adults and immatures. The descriptions of adults of the type species of Tegoribates, T. subniger Ewing, and other North American species, T. americanus Hammer and T. bryophilus Woolley, are expanded and immatures of T. americanus are described for the first time. Immatures of Protectoribates are apheredermous whereas those of Tegoribates are eupheredermous, though retaining centrodorsal setae. Scutozetes Hammer 1952 is transferred from Tegoribatidae to Ceratozetidae after re-examination of type material. I provide a revised diagnosis for Tegoribates and a key to tegoribatid genera and species for North America. Finally, I provide a revised diagnosis for Tegoribatidae based on world genera.

We propose a new species of the oribatid mite genus Fenestrobates (Oribatellidae), F. marauni sp. nov., based on adult specimens from Ecuador. The type species, F. capucinus Balogh and Mahunka, 1969 from Bolivia, is redescribed. We confirm the recombination of two species from the Russian Far East, F. rossicus Krivolutsky, 1974 from the Primorsky Region, and F. vicinus Ryabinin, 1975 from the Khabarovsk Region, as Oribatella rossicus (Krivolutsky) and O. vicinus (Ryabinin), and we give revised diagnoses for each. We present a new diagnosis for Fenestrobates and argue for its recognition as a genus distinct from Oribatella on the basis of the apomorphic development of a large, pouch-like depression positioned ventrally between pedotectum I and the lateral body wall, and absence of small ridges anteriorly on the notogaster. Based on these changes and new information, we give a revised diagnosis for Oribatellidae and provide a key to included genera.

Three new species of oribatid mites in two genera of Mycobatidae are recorded from canopy habitats of coniferous temperate rainforest and montane forest in the Pacific Northwest of North America. These species, Mycobates acuspidatussp.nov., M. corticeussp.nov., and Zachvatkinibates epiphytossp.nov., are described on the basis of adults and immatures. The previous key for adult Mycobates species of America north of Mexico is modified to include these new species, and a key for adults is given for the three species of Zachvatkinibates now known from North America.

The boundaries between terrestrial and aquatic ecosystems, known as critical transition zones (CTZ), are dynamic interfaces for fluxes of water, sediment, solutes, and gases. Moreover, they often support unique or diverse biotas. Soils, especially those of riparian zones, have not been recognized as CTZ even though they play a critical role in regulating the hydrologic pathways of infiltration and leaching, or runoff and erosion, which can cumulatively affect biogeochemical processes and human livelihoods at landscape scales. In this review, we show how the processes that regulate hydrologic fluxes across and through soil CTZ are influenced by the activities of soil biota. Our message is fourfold. First, there are a variety of ways in which soil biodiversity, in terms of richness and dominance, can influence hydrological pathways in soil and thus the transfer of materials from terrestrial to aquatic ecosystems. Second, the influence of soil organisms on these hydrological pathways is very much interlinked with other environmental, soil biophysical, and vegetation factors that operate at different spatial and temporal scales. Third, we propose that the influence of soil biodiversity on hydrological pathways is most apparent (or identifiable), relative to other factors, in situations that lead to the dominance of certain organisms, such as larger fauna. Fourth, soils are buffered against environmental change by biophysical properties that have developed over long periods of time. Therefore, the effects of changes in soil biodiversity on hydrological processes at the ecosystem scale might be delayed and become most apparent in the long term.

Six species of oribatid mites (Acari: Ceratozetidae) in six genera were recorded from a variety of arboreal habitats in western Canada, including the canopy of temperate rainforest, montane forest, and the leaves of shrubs. Four of these species are new to science and are described: Sphaerozetes winchesterisp.nov., on the basis of adults; and Dentizetes ledensissp.nov., Melanozetes crossleyisp.nov., and Neogymnobates marilynaesp.nov., on the basis of adults and immatures. Jugatala tuberosa Ewing is redescribed from both adults and immatures, a new observation being that adults have seven pairs of notogastral porose areas. The placement of the genus Jugatala Ewing in Ceratozetidae is confirmed. Latilamellobates baloghi (Mahunka) is newly recorded from North America, and the taxonomy of the genus is discussed. The major differences among these six species are presented in tabular format.

The general ecology, biology, life history, and available sources for identification of oribatid mites (including Astigmata), the most numerically dominant arachnid group in the organic horizons of most soils, is reviewed. I use this information as the basis to evaluate data on their role for bioindication in agroecosystems, with the following conclusions: (a) oribatid mites with their low metabolic rates, slow development and low fecundity cannot respond rapidly to resource flushes: astigmatic mites with their contrasting life history traits can respond rapidly; (b) because many agroecosystems represent early successional stages, the oribatid species present are those found in heavily disturbed or early successional habitats, wherever these occur; (c) use of oribatid mites for bioindication must incorporate information on life history traits, and habitat and niche profiles for species.

▪ Abstract Although often unobserved or ignored, mites usually exceed all other arthropods in abundance in forest canopies. Second in species richness only to canopy insects, the arboreal acarofauna is composed of multiple lineages of predators, scavengers, grazers, animal associates, and plant parasites that each have radiated extensively in canopy habitats. The canopy fauna is largely complementary to the mite fauna of the forest floor, suggesting that estimates of more than one million living species of mites are not extreme. Most mites are less than a millimeter in length as adults, and canopy mites tend to be smaller than species from other habitats. Even among mites, however, very small species are relatively rare, and diversity increases with decreasing size only to the penultimate size class (0.316–1 mm). This pattern may be explained by declines in microhabitat diversity or host specificity as the limit of body size in a group of organisms is approached.

Four new species of the oribatid mite genus Carabodes from western North America are described, based on adult specimens: Carabodes california known from California, C. colorado from British Columbia, Alberta, Idaho, Wyoming, Colorado, Arizona, and New Mexico, C. dickinsoni from British Columbia, Washington, Oregon, and California, and C. hoh from British Columbia, Washington, Oregon, and California. We provide an expanded diagnosis of the genus, including information on integumental birefringence, chaetotaxy, palptarsal setation, and position of lyrifissure iad. We present a table of character states and a diagnostic key for the 28 species, as well as a summary of their distributions.

Thirty-six species of Oribatida (2596 specimens), representing 29 genera and 21 families were recorded from replicated Malaise traps positioned in the canopy and on the forest floor of old-growth Sitka spruce (Picea sitchensis) on western Vancouver Island, Canada, and in an adjacent clear-cut. Traps were sampled bi-weekly throughout the growing season, and colonization was 100% in the canopy, 91% in the forest floor and 47% in the clear-cut. Nine of the species recovered were not recorded from this site using high gradient extractions of moss from canopy or forest floor. Thirty of these species were Brachypylina, with the families Eremaeidae, Peloppiidae and Ceratozetidae represented by three or more species. Colonizing specimens were predominantly adult, and represent sexual taxa: immatures comprised only 0.9–4.2% of specimens. Ceratoppia spp. , Eporibatula sp.1, Dorycranosus sp.1, Sphaerozetes sp.1 and Oribatella sp.1 had a frequency >50% in the forest floor traps, and Eporibatula sp.1, Sphaerozetes sp.1 and Dendrozetes sp.1 had a frequency >50% in canopy traps. Phoresy as a source of the oribatid fauna in the Malaise traps is unlikely as, of the species represented, only Paraleius sp.1 is modified for this mode of dispersal. The number of species recorded from the traps, and the frequency, relative abundance, and seasonality of many of them, support the hypothesis that active dispersal by random movement is an important mode of colonization of canopy habitats.

Species of the oribatid mite genus Tegeocranellus from North and Central America are discussed, and immatures are described for the first time. Six new species are described and keyed: Tegeocranellus alas from Costa Rica, T. barbarae from Alabama, Mississippi, and Florida, T. kethleyi from Alabama and Mississippi, T. mississippii from Louisiana and Texas, T. muscorum known from Ontario to Florida, and T. mediolamellatus from Guatemala. Descriptions of T. alas, T. barbarae, T. mediolamellatus, and T. muscorum are based on adults and immatures, and those of the other two species on adults only. I expand the generic diagnosis to include information on the apheredermous, plicate immatures, and present a character analysis hypothesizing that the monogeneric family Tegeocranellidae is a member of the Ameronothroidea, closely related to Selenoribatidae and Fortuyniidae.

Species in the oribatid mite genus Tectoribates are primarily Palaearctic and Neotropical, with scattered, unidentified records from North America. Herein, we describe 3 new Tectoribates species from dry forest and prairie habitats in North America: T. alcecampestris sp. nov., from Alberta, T. borealis sp. nov., from southern Alberta and Ontario, both on the basis of adults and nymphs, and T. campestris sp. nov., from dry grassland habitats in Ontario and Kansas, on the basis of adults. We provide a revised and expanded diagnosis for adults of Tectoribates. We assess relationships of Tectoribates, using characters of adults and newly discovered apheredermous, plicate immatures. We include observations on Pseudotectoribates which is closely related to Tectoribates. The closest relatives of these genera are hypothesised to be among the Tegoribatidae (Achipterioidea) rather than among the Achipteriidae (Achipterioidea), Oribatellidae (Oribatelloidea), or Ceratozetoidea, as suggested in previous classifications. Finally, we give a key to adults of the world fauna of Tectoribates.

The aquatic oribatid mite genus Mucronothrus (Trhypochthoniidae) is redescribed on the basis of characters of adults and immatures and its familial placement is reviewed. It is represented in North America by two species. Mucronothrus nasalis, a globally widespread species, is redescribed on the basis of all active instars. In Canada it is now known from Newfoundland, New Brunswick, Ontario, Quebec, Saskatchewan, Alberta, and British Columbia and in the U.S.A. from Oregon and Colorado. Ancillary new distribution records include England and Cape Horn. Misinterpretations of homologies of leg setae in the literature are corrected. A population near Toronto, Ontario, was examined for variation in genital and leg setation; this conforms well with previously described geographic patterns (J. Travé). This population exhibits previously unknown variation in cheliceral form. A second species, Mucronothrus willmanni n.sp., is proposed on the basis of adults and tritonymphs. Current records are from California, Oregon, and Montana, where it inhabits riffles in streams. Only females are known and, like M. nasalis, the species appears to be thelytokous.

A new species of oribatid mites of the genus Safrobates (Oribatida, Punctoribatidae) is described from the soil of alpine herbaceous snowbank of the Central Otago region in the South Island of New Zealand. Safrobates insignis sp. nov. differs from S. miniporus Mahunka, 1989 and S. gerdi Ermilov & Minor, 2016 in having penicillate subcapitular setae h, epimeral setae (except 1c) and aggenital setae, the presence of neotrichy on epimere I, four pairs of notogastral porose areas, six pairs of genital setae and tridactylous legs. Accessory information on Safrobates and the relevance of some morphological traits of the new species are discussed. A revised generic diagnosis is given, relationships of Safrobates, Macrogena and Magellozetes are discussed, and Magellozetes is transferred from Ceratozetidae to Punctoribatidae. An identification key to known species of Safrobates is provided.

Although mites are one of the most abundant and diverse groups of arthropods, they are rarely targeted for detailed biodiversity surveys due to taxonomic constraints. We address this gap through DNA barcoding, evaluating acarine diversity at Churchill, Manitoba, a site on the tundra-taiga transition. Barcode analysis of 6279 specimens revealed nearly 900 presumptive species of mites with high species turnover between substrates and between forested and non-forested sites. Accumulation curves have not reached an asymptote for any of the three mite orders investigated, and estimates suggest that more than 1200 species of Acari occur at this locality. The coupling of DNA barcode results with taxonomic assignments revealed that Trombidiformes compose 49% of the fauna, a larger fraction than expected based on prior studies. This investigation demonstrates the efficacy of DNA barcoding in facilitating biodiversity assessments of hyperdiverse taxa.

This paper reviews and summarizes preliminary data on the taxonomy, distribution, and ecology of oribatid mites of Canadian peatlands, primarily those of eastern Canada. This fauna is a heterogenous assemblage comprising 71 species in 49 genera and 34 families, found in four main types of habitats: aquatic, mesic, xeric, and epigeal. About half of the oribatid fauna of peatlands, and most aquatic species, are restricted in distribution to the Nearctic. Oribatid taxa known or suspected to be parthenogenetic are much better represented in peatlands than in the general Canadian fauna. Data on the feeding habits of odonate larvae in Newfoundland bog pools, based on gut content analysis, show that oribatid mites, in particular species of Limnozetes Hull and Hydrozetes Berlese, are common prey of species of Aeshna Fabricius, Leucorrhina Brittinger, and Libellula L. A synopsis of available data suggests that assemblages of Limnozetes species may be useful in characterizing peatlands.

We present the first study of the systematics, ecology, and biogeography of an arboreal oribatid mite from Australia, describe all stages of Adhaesozetes polyphyllos sp.nov., propose new diagnoses for its genus and family, and present a character analysis demonstrating that the family Adhaesozetidae is a member of the Licneremaeoidea. Certain character states, especially the expanded tarsal pulvilli, are interpreted as adaptations to arboreal life. Adhaesozetes polyphyllos grazes on epiphyllic fungi and prefers leaves with smooth surfaces or with closely appressed hairs. It inhabits at least 51 species of trees, shrubs, vines, and ferns in pockets of rainforest in eastern Australia. It is often the most abundant leaf-inhabiting oribatid mite in the cool- to warm-temperate rainforests of Tasmania and Victoria, and inhabits montane subtropical to tropical rainforests at least as far north as Mount Lewis (16°32′S). It appears to be absent from lowland subtropical to tropical rainforests, which suggests an ancient relationship with the Antarctic elements of the Australian flora. Populations are bisexual, with females representing an average of 55% of the adult population. At Wilson's Promontory, populations increase from late winter to midsummer, but all stages are present throughout the year. Females use their ovipositors to lay eggs in protected sites (e.g., insect damage or leaf domatia), often within the cast skins of immature mites.

The oribatid family Eremaeidae is represented in North America by two genera, Eremaeus and Eueremaeus, both widely distributed throughout the Palaearctic and Nearctic regions. In North America species in both genera are found in moist to arid habitats from New Mexico to the High Arctic. Reproduction is sexual, and both immatures and adults feed mainly on fungi.Revised diagnoses are presented for the Eremaeidae and genera Eremaeus and Eueremaeus. Eighteen species of Eremaeus, of which 14 are newly proposed, and 24 species of Eueremaeus, of which 15 are newly proposed, are recognized. Identification keys are provided for the world genera of Eremaeidae, and for adults of Eremaeus and Eueremaeus of North America. All but one North American species of these genera are described, and their geographical distributions mapped.North American Eremaeus species include E. appalachicus sp. no v., E. boreomontanus sp. nov., E. brevitarsus (Ewing), E. californiensis sp. nov., E. gracilis sp. nov., E. grandis Hammer, E. kananaskis sp. nov., E. kevani sp. nov., E. megistos sp. nov., E. monticolus sp. nov., E. nortoni sp. nov., E. occidentalis sp. nov., E. oresbios sp. nov., E. plumosus Woolley, E. porosus sp. nov., E. salish sp. nov., E. translamellatus Hammer, and E. walteri sp. nov. The immatures of four of these, E. kananaskis, E. occidentalis, E. oresbios, and E. translamellatus, are described.North American Eueremaeus include Eu. acostulatus sp. nov., Eu. aridulus sp. nov., Eu. columbianus (Berlese), Eu. foveolatus (Hammer), Eu. marshalli sp. nov., Eu. masinasin sp. nov., Eu. michaeli sp. nov., Eu. nahani sp. nov., Eu. nemoralis sp. nov., Eu. proximus (Berlese) comb, nov., Eu. woolleyi (Higgins) comb, nov., Eu. yukonensis sp. nov., and three informal species groups with the following included species in North America: (1) Eu. trionus group—Eu. trionus (Higgins) comb, nov., (2) Eu. stiktos group—Eu. carinatus sp. nov., Eu. higginsi sp. nov., Eu. stiktos (Higgins) comb, nov., Eu. tetrosus (Higgins) comb, nov., (3) Eu. chiatous group—Eu. alvordensis sp. nov., Eu. aysineep sp. nov., Eu. chiatous (Higgins) comb, nov., Eu. danos sp. nov., Eu. lindquisti sp. nov., Eu. magniporosus (Wallwork) comb, nov., and Eu. osoyoosensis sp. nov. The immatures of nine of these, Eu. masinasin, Eu. nahani, Eu. carinatus, Eu. higginsi, Eu. columbianus, Eu. proximus, Eu. woolleyi, Eu. stiktos, and Eu. tetrosus, are described. Kartoeremaeus reevesi Higgins and Eremaeus politus Banks are considered junior subjective synonyms of Eueremaeus columbianus (Berlese).A cladistic analysis of the genera comprising Eremaeidae: Eremaeus, Tricheremaeus, Eueremaeus (and included species groups), Proteremaeus, Carinabella, and Asperemaeus, indicates that Eremaeus is the sister taxon of Carinabella, and that Eueremaeus is the sister taxon of Proteremaeus. Tricheremaeus is the sister taxon of Eremaeus + Carinabella, and Asperemaeus is the sister taxon of Eueremaeus + Proteremaeus. The relationship of the Eremaeidae to the Megeremaeidae and Zetorchestidae is presented. Finally, I discuss the ecology and distribution of North American species of Eremaeidae.

The oribatid mite genus Oribatella includes over 100 named species, none of which shows distinct sexual dimorphism in the octotaxic system of dermal glands. We propose a new species of this genus, Oribatella canadensis sp, nov., collected from dry soil habitats in western Canada, that shows distinct dimorphism in these dermal glands, the first record of this dimorphism in the Oribatelloidea. The posterior pair of glands in males, but not females, is enlarged and associated with a shallow, medial pit-tubercle complex, and is generally similar to convergent dimorphisms in some genera of Mochlozetidae (Oripodoidea), Mycobatidae (Ceratozetoidea) and Galumnidae (Galumnoidea). We describe this species based on adult and nymphal stages, and expand the diagnosis of the genus to accommodate the newly described immatures. We review the expression of sexual dimorphism in brachypyline oribatid mites and discuss its association with periodically dry habitats.

Few soil invertebrate species are available for the toxic assessment of soils from boreal or other northern ecozones, yet these soils cover the majority of Canada's landmass as well as significant portions of Eurasia. Oppia nitens (C.L. Koch) is an herbivorous and fungivorous oribatid mite found in soil throughout Holarctic regions, including Canada. Soil tests using O. nitens were performed using 15 different forest soil types and horizons to investigate test variability in adult survival and reproduction. Adult survival (86.1 ± 1.1%) was consistent across soil types, with a coefficient of variation (CV) of 15%. However, reproduction varied significantly, ranging from 2.9 (±1.1) to 86.2 (±11.7) individuals, with a corresponding CV of 118 and 30%, respectively. Of the soil factors assessed (NH3, NO3, pH, phosphorus [P], organic matter content (OM), carbon:nitrogen (C:N), sand, silt, clay, and sodium adsorption ratio), soil organic matter (OM) explained 68% of the variation observed for reproduction. Increasing the OM using Sphagnum sp. peat moss resulted in optimal reproduction at 7% OM (8% peat content) with the lowest variability (CV of 20%). When assessing the toxicity of a reference chemical, boric acid, the effect of peat amendment reduced lethality to adults with no observable difference on reproduction. The use an age-synchronized culture reduced the test variability for reproduction relative to the use of unsynchronized cultures. Oppia nitens is a good candidate species for a standardized test design, with adult survival easily assessed in a relatively simple design. A long-term reproduction test with O. nitens will require the use of a synchronized population and, on occasion, OM amendment when testing soils with low organic matter content. Environ. Toxicol. Chem. 2010;29:971–979. © 2009 SETAC