A list of oribatid mites (Acari,Oribatida) of Vietnam

A species list of identified oribatid mite taxa (Acari, Oribatida) in the fauna of Vietnam is provided. During 1967–2015, a total of 535 species/subspecies from 222 genera and 81 families was registered. Of these, 194 species/subspecies were described as new for science from Vietnam.     

Phylogenetic relationships among the Canary Island Steganacaridae (Acari, Oribatida) inferred from mitochondrial DNA sequence data

The mite genus Steganacarus is represented in the Canary Islands by three endemic species, one recently discovered species, and several morphotypes of uncertain taxonomic position. We used a fragment of the mitochondrial cytochrome oxidase I gene to reconstruct the phylogenetic relationships among representatives of the different taxa from the three central islands of the archipelago, Tenerife, La Gomera and Gran Canaria. Sequence data were analysed by both maximum parsimony and maximum likelihood methods. The inferred phylogenetic relationships do not correlate well with current morphological taxonomy but reveal four deeply divergent and geographically coherent lineages, one each on Gran Canaria and La Gomera and two on Tenerife. No pattern of molecular differentiation was observed among different morphotypes. Possible explanations for this incongruence are suggested in relation to the ecology and biogeography of the group. A recently discovered Steganacarus species from La Gomera, morphologically quite distinct from the other Canarian Steganacarus, is clearly identified as a taxon distantly related to all the other Canarian samples.     

No evidence for the 'Meselson effect' in parthenogenetic oribatid mites (Oribatida, Acari)

It has been hypothesized that in ancient apomictic, nonrecombining lineages the two alleles of a single copy gene will become highly divergent as a result of the independent accumulation of mutations (Meselson effect). We used a partial sequence of the elongation factor-1alpha (ef-1alpha) and the heat shock protein 82 (hsp82) genes to test this hypothesis for putative ancient parthenogenetic oribatid mite lineages. In addition, we tested if the hsp82 gene is fully transcribed by sequencing the cDNA and we also tested if there is evidence for recombination and gene conversion in sexual and parthenogenetic oribatid mite species. The average maximum intra-specific divergence in the ef-1alpha was 2.7% in three parthenogenetic species and 8.6% in three sexual species; the average maximum intra-individual genetic divergence was 0.9% in the parthenogenetic and 6.0% in the sexual species. In the hsp82 gene the average maximum intra-individual genetic divergence in the sexual species Steganacarus magnus and in the parthenogenetic species Platynothrus peltifer was 1.1% and 1.2%, respectively. None of the differences were statistically significant. The cDNA data indicated that the hsp82 sequence is transcribed and intron-free. Likelihood permutation tests indicate that ef-1alpha has undergone recombination in all three studied sexual species and gene conversion in two of the sexual species, but neither process has occurred in any of the parthenogenetic species. No evidence for recombination or gene conversion was found for sexual or parthenogenetic oribatid mite species in the hsp 82 gene. There appears to be no Meselson effect in parthenogenetic oribatid mite species. Presumably, their low genetic divergence is due to automixis, other homogenizing mechanisms or strong selection to keep both the ef-1alpha and the hsp82 gene functioning.     

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, c₂, p₁, epimeral setae 3b and adanal setae ad₁ and the presence of prodorsal lateral ridges.     

The moss mites of the Cheviot (Acari: Oribatei)

A faunal list of oribatid mites collected from the summit of the Cheviot, Northumberland, is given, together with notes on the taxonomy and distribution of several of the species. Special attention is paid to the Arctic-alpine and European-alpine species and the list provides further support for the view that the upland areas of Britain are characterized by a common group of oribatid species. It is suggested that these species may be cold hardy or cold tolerant with relatively high supercooling points, enabling them to survive the winter at these higher altitudes.     

Molecular phylogeny of oribatid mites (Oribatida, Acari): evidence for multiple radiations of parthenogenetic lineages

Nucleotide sequences of the D3 expansion segment and its flanking regions of the 28S rDNA gene were used to evaluate phylogenetic relationships among representative sexual and asexual oribatid mites (Oribatida, Acariformes). The aim of this study was to investigate the hypothesis that oribatid mites consist of species-rich clusters of asexual species that may have radiated while being parthenogenetic. Furthermore, the systematic position of the astigmate mites (Astigmata, Acariformes) which have been hypothesised to represent a paedomorphic lineage within the oribatid mites, is investigated. This is the first phylogenetic tree for oribatid mites s.l. (incl. Astigmata) based on nucleotide sequences. Intraspecific genetic variation in the D3 region was very low, confirming the hypothesis that this region is a good species marker. Results from neighbour joining (NJ) and maximum parsimony (MP) algorithms indicate that several species-rich parthenogenetic groups like Camisiidae, Nanhermanniidae and Malaconothridae are monophyletic, consistent with the hypothesis that some oribatid mite groups diversified despite being parthenogenetic. The MP and maximum likelihood (ML) method indicated that the D3 region is a good tool for elucidating the relationship of oribatid mite species on a small scale(genera, families) but is not reliable for large-scale taxonomy, because branches from the NJ algorithm collapsed in the MP and ML tree. In all trees calculated by different algorithms the Astigmata clustered within the oribatid mites, as proposed earlier.     

Anatomy and function of the ptychoid defensive mechanism in the mite Euphthiracarus cooki (Acari: Oribatida)

Ptychoidy is a defensive adaptation of several groups of oribatid mites in which legs and coxisternum can be fully retracted into the opisthosoma and protected by a ventrally deflected prodorsum, resulting in a seed-like appearance. Using Euphthiracarus cooki as a model, we examined details of exoskeletal and muscular anatomy in combination with studies of live individuals to provide the first functional analysis of ptychoidy. There are two main functional components: the first is a set of exoskeletal and muscular adaptations, mostly of the podosoma and prodorsum, that combine to effect leg withdrawal and prodorsal deflection; the second comprises adaptations of the opisthosoma that allow control of hydrostatic pressure during the large hemocoel volume adjustments associated with ptychoidy. Adaptations important in the closing process (enptychosis) are found in four body regions. Much of the podosomal exoskeleton (especially pleural) is unsclerotized, which facilitates leg retraction and prodorsal deflection during enptychosis. The coxisternum has several flexible furrows along which it folds in order to bring legs into a tightly parallel arrangement. The prodorsum has specialized attachment surfaces (manubrium and inferior retractor process) for retractor muscles and a paired bothridial scale that participates in prodorsal alignment during enptychosis. The subcapitulum has a prominent capitular apodeme on which important retractor muscles insert. The mineralized notogaster has an anterior "collar" that accommodates the retracted prodorsum; it includes paired notches and receptacles that accommodate the bothridial scales, thereby creating a temporary fixed axis for rotation of the prodorsum in a "lazy hinge" mechanism. Specialized muscles form the retractor system; most conspicuous are the large coxisternal retractors and prodorsal retractors, both of which originate on the notogaster. Other components have adjustor roles; among them are muscles of the endosternal system that control retraction of the subcapitulum and assist leg retraction, and the dorsoventral muscles which adjust the folded coxisternum. Hemolymph pressure control is a function of the opisthosoma, where the principle exoskeletal elements form a pleated venter, having a cross-sectional shape like an inverted "W." Paired holoventral plates (each representing fused genital, aggenital, anal, and anal plates) form the inner angle and are flanked by paired plicature plates. The holoventral plates are connected medially in two ways : 1) by three permanent bridges of sclerotized cuticle that include an anterior phragmatal bridge and two widely spaced, hollow apodemes (preanal, postanal); 2) by temporary zipper-like closures of two different types. Lateral compression of the pleats is effected by a series of transversely arranged, lateral compressor muscles that run from plicature to holoventral plate edges, and from holoventral plate edges to the medial apodemes. Compression increases hydrostatic pressure in the opisthosoma and stores energy in both the slightly deformed, mineralized notogaster and in the three holoventral bridges. During normal activity the compressor system is active and the inflated podosomal region provides support for the extended legs. When the mite is irritated, the prodorsum is hydraulically ejected from its active position in the notogastral collar, then relaxation of the compressors causes a fall in hemolymph pressure and return of the notogaster to an undeformed condition. Muscles of the retractor system then act in specific sequence to retract and adjust the coxisternum and prodorsum until they are precisely positioned at the completion of enptychosis. The process takes between 0.5 and 1 sec. When irritation ceases, partial opening allows sensory leg hairs to "test" the environment. Resumption of normal, active posture (ecptychosis) involves activation of the lateral compressor system and hydraulic inflation of the podosoma, through which legs are extended and the prodorsum is reflected.     

Species of the family Cepheidae Berlese, 1896 (Acarida: Oribatida) from the Maghreb

The species of cepheid mites (Acarida, Oribatida, Cepheidae) from Maghrebian soils are listed and taxonomically revised. The six species, including two new entities, one of which represents the new genus Tereticepheus , offer interesting data for a biogeographical discussion of faunal movements in the western Mediterranean area during the last 20 million years.     

Oribatid mites of the superfamily Trizetoidea Ewing, 1917 (Acari,Oribatida) from Peru

Two new species of the oribatid mite superfamily Trizetoidea (Acari, Oribatida) are described from Peru. Rhynchoribates (Rhynchoribatodes) rioyuyapichisensis Ermilov, sp. n. differs from the other species of the subgenus by the long flagelliform notogastral setae. Rhynchoppia puertoincaensis Ermilov, sp. n. is morphologically similar to R. capillata (Balogh, 1963), but differs by the shape and in a greater number of rostral teeth, in the number and a smaller length of notogastral setae, and in the number of genital setae. The genus Rhynchoppia (Balogh 1968) is recorded from the Neotropical Region for the first time, while Rhynchoribates (Rhynchoribatodes) brasiliensis Woas 1986 is new to the fauna of Peru.     

Local–regional boundary shifts in oribatid mite (Acari: Oribatida) communities: species–area relationships in arboreal habitat islands of a coastal temperate rain forest, Vancouver Island, Canada

Aim This study investigates the species–area relationship (SAR) for oribatid mite communities of isolated suspended soil habitats, and compares the shape and slope of the SAR with a nested data set collected over three spatial scales (core, patch and tree level). We investigate whether scale dependence is exhibited in the nested sampling design, use multivariate regression models to elucidate factors affecting richness and abundance patterns, and ask whether the community composition of oribatid mites changes in suspended soil patches of different sizes. Location Walbran Valley, Vancouver Island, Canada. Methods A total of 216 core samples were collected from 72 small, medium and large isolated suspended soil habitats in six western redcedar trees in June 2005. The relationship between oribatid species richness and habitat volume was modelled for suspended soil habitat isolates (type 3) and a nested sampling design (type 1) over multiple spatial scales. Nonlinear estimation parameterized linear, power and Weibull function regression models for both SAR designs, and these were assessed for best fit using R² and Akaike's information criteria (ΔAIC) values. Factors affecting oribatid mite species richness and standardized abundance (number per g dry weight) were analysed by anova and linear regression models. Results Sixty‐seven species of oribatid mites were identified from 9064 adult specimens. Surface area and moisture content of suspended soils contributed to the variation in species richness, while overall oribatid mite abundance was explained by moisture and depth. A power‐law function best described the isolate SAR (S = 3.97 × A^0.12, R² = 0.247, F_1,70 = 22.450, P < 0.001), although linear and Weibull functions were also valid models. Oribatid mite species richness in nested samples closely fitted a power‐law model (S = 1.96 × A^0.39, R² = 0.854, F_1,18 = 2693.6, P < 0.001). The nested SAR constructed over spatial scales of core, patch and tree levels proved to be scale‐independent. Main conclusions Unique microhabitats provided by well developed suspended soil accumulations are a habitat template responsible for the diversity of canopy oribatid mites. Species–area relationships of isolate vs. nested species richness data differed in the rate of accumulation of species with increased area. We suggest that colonization history, stability of suspended soil environments, and structural habitat complexity at local and regional scales are major determinants of arboreal oribatid mite species richness.     

Three new species of oribatid mites of the genus Pergalumna (Acari: Oribatida: Galumnidae) from India

Three new oribatid mite species of the genus Pergalumna (Galumnidae) are described from growing mosses on rocks near a water stream in India. Pergalumna paraclericata sp. n. is very similar morphologically to Carinogalumna clericata (Berlese, 1914), however, it differs from the latter by the structure of lamellar lines and number of notogastral porose areas. Pergalumna minipora sp. n. is very similar morphologically to Pergalumna bifissurata Hammer, 1972, however, it differs from the latter by the body size and the presence of prodorsal ridges and a median pore. Pergalumna paracattienica sp. n. is very similar morphologically to Pergalumna cattienica Ermilov & Anichkin, 2011, however, it differs from the latter by the number of notogastral porose areas and the body integument on the ventral plate.     

中国广翼甲螨亚属一新种及一新纪录种（蜱螨亚纲：甲螨亚目：大翼甲螨科）

记述采自中国陕西省和贵州省的广翼甲螨亚属Flagellozetes(Cosmogalumna)1新种。该新种与分布在菲利宾的弗拉基米尔广翼甲螨Flagellozetes(Cosmogalumna)vladopesici ErmilovCorpuz-Raros,2015相似,但区别在于:翅形体上不具有多边形网状结构;前背板中部具有不规则的突节;后背板中央孔明显。首次记录瑕饰广翼甲螨Flagellozetes(Cosmogalumna)ornata Aoki,1988在中国的分布。     

New Data on the fauna of oribatid mites (Acari,Oribatida) from the polar Urals

The fauna of oribatid mites in soils of the polar Ural mountains (the lower Malaya Paipudyna River, Labytnangi District, Yamal-Nenets Autonomous Area, 67°06′N, 65°20′E) was studied. Samples from the upper soil layer and litter were collected along a transect running from the floodplain to the mountain lichen tundra (from 150 to 520 m a.s.l.. A total of about 10 thousand mites belonging to 82 species of 34 families were collected, and the distribution of some species in various biotopes was recorded. 46 species and 11 families (Hypochthoniidae, Euphthiracaridae, Phthiracaridae, Nanhermanniidae, Trhypochthoniidae, Cepheidae, Eremaeidae, Thyrisomidae, Micreremidae, Passalozetidae, and Scutoverticidae) are new to the fauna of the polar Urals. Together with these new taxa, the oribatid fauna of the polar Urals comprises not less than 106 species of 34 families. This fauna consists mainly of species with the wide polyzonal geographical distribution.     

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.     

The evolution and distribution of Calyptozetes sarekensis (Acari: Oribatei)

Calyptozetes sarekensis , an oribatid mite found predominantly, though not exclusively in lichens, inhabits regions within the arctic circle and subarctically between latitudes 60^o and 70^o (Swedish Lapland, Norway, Bear Island, Spitzbergen, Jan Mayen, Iceland, Greenland, northern Canada). In recent years, however, the species has been recorded from a number of montane sites in Great Britain and southern Europe. There would appear to be only two possible explanations for die discontinuous distribution of this mite. (1) The species has been transported from its main arctic and subarctic area of distribution to its southern montane outposts by some agent (driftwood, birds, wind), or (2) in Britain and southern Europe it represents a relict species of the Ice Age, left stranded on high ground after the final retreat of the ice. Evidence is presented in support of the second hypothesis. In addition, it is suggested that its presence on the different land masses of its main arctic and subarctic range, which are separated from each other by wide stretches of ocean, could be explained by die hypothesis that it is a very ancient species daring from the time Laurasia was in existence some 60 or more million years ago. The alternative hypothesis of transportation of the species between one or more of these areas, however, is by no means ruled out.     

Light and electron microscope studies on Helicosporidium sp. parasitizing oribatid mites (Oribatei,Acarina) and collembola (Apterygota,Insecta) in forest soils

The life cycle of Helicosporidium sp. parasitizing natural populations of oribatid mites and collembolans in forest soils, is described by means of light, Nomarski interference, and electron microscopy. The ultrastructure of some early sporogonic stages (cysts), the young (maturing) spore, and the mature spore is discussed. Some data on the host-parasite relationships and prevalence of infection are presented.     

Peruvian oribatid mites (Acari,Oribatida) from the German Biological Expedition,with description of a new species of the genus Pergalumna

The present study is based on oribatid mite material (Acari, Oribatida) collected during the German Expedition in 2011 in Peru. An annotated checklist of identified oribatid mites, including 16 species from 14 genera and 8 families, is provided. Thirteen species and two genera (Notohermannia, Zetomimus) are recorded for the first time in Peru; the genus Notohermannia and species Notohermannia obtusa are recorded for the first time in the Neotropical region. A new species of the genus Pergalumna (Galumnidae), Pergalumna paraboliviana sp. n., is described. The new species is most similar to Pergalumna boliviana Ermilov, 2013 from Bolivia, however, it differs from the latter by the body size, morphology of porose areas A1 and the presence of interlamellar setae.     

Studies on the moss mites of Snowdonia (Acari: Oribatei). 2. The Cnicht

A faunal list of oribatid mites collected from the summit of the Cnicht, Snowdonia, at 2265 ft is given, together with critical notes on the taxonomy and distribution of several of the species. The list provides further evidence of the presence of arctic-alpine and European-alpine species of Oribatei on the mountain peaks of Britain. A comparison of the faunal list with lists of species recorded by the author on another peak in Snowdonia and on high ground in other parts of Britain (Peak District, Lake District) and by Block in Westmorland, provides evidence of a group of additional species which can be regarded as characteristic of upland areas in general of Britain and Europe.