Morphological ontogeny, distribution of Hermannia scabra (Acari: Oribatida: Hermanniidae) in Svalbard and descriptive population parameters

The morphological ontogeny and distribution of Hermannia scabra (L. Koch, 1879) in Arctic Svalbard and descriptive population parameters were investigated. All instars of H. scabra are stocky, as in other species of Hermannia Nicolet, 1855, and have the same gastronotal setal ontogeny (12 pairs in the larve and 16 pairs in the nymphs and adults). In this species, the prodorsal setae are similar to other species of Hermannia, except for the bothridial seta which is clavate, as in H. reticulata Thorell, 1871. In other species of Hermannia the bothridial seta is setiform. Most prodorsal and gastronotal setae of H. scabra are phylliform whereas in other Hermannia species they are thickened. The number of epimeral setae in the nymphs and adults and the ontogeny of leg setae are characteristic for H. scabra. This species has a holarctic distribution and in Svalbard is not as common as H. reticulata, but it achieves higher density than the latter species, mainly due to the abundance of juveniles. Hermannia scabra prefers moist and wet localities, and in Svalbard the highest density is achieved in vegetation class 8 (wet vegetated flats, beaches, slopes and river fans with some exposed Dryas vegetation and graminoids Luzula sp.)

Seasonal dynamics of mites (Acari) in pastures and meadows in Poland, with species analysis of Oribatida

The study involved three pastures, grazed by geese, goats and fallow deer, and three nearby meadows (control plots) situated in north-central Poland. Samples of 150 cm3 each (6 cm of soil and 3 cm of lower parts of plants) were collected in spring, summer and autumn 2016 and 2017 in 10 replications, 360 samples in total. This material included 22.561 mites, among which Oribatida accounted for 69%, Mesostigmata for 21%, and other mites for 10%. At most study sites, both pastures and meadows, no significant seasonal differences in the abundance of Oribatida and Mesostigmata were seen. Such differences were only observed for the third category of other mites that were the most abundant in spring and usually the least abundant in autumn. Also species diversity of Oribatida differed between the seasons – in all pastures it was the highest in summer and the lowest in spring, while in all meadows it was the highest in spring and decreased towards autumn. Oribatid species were more affected by the habitats than by seasons, as some species were strongly associated with pastures (Platynothrus peltifer), other with meadows (Achipteria coleoptrata, Liebstadia similis, Metabelba pulverosa, Scheloribates laevigatus and Sellnickochthonius immaculatus), and some (Eupelops occultus and Tectocepheus velatus) were abundant in both habitats. Although the effect of seasonality was weaker than that of the habitat, it was still perceptible. Platynothrus peltifer was most associated with autumn, T. velatus with spring, E. occultus with spring and summer and L. similis with summer.publishedVersio

Type of broadleaf forest matters most for ptyctimous mite communities (Acari, Oribatida) in Norway

We studied ptyctimous moss mites, which are characteristic of forest habitats, in Norwegian broadleaf forests considered as biodiversity hotspot areas in Fennoscandia. The study aimed to evaluate the effect of different factors (regional locality, annual precipitation, mean annual temperature, forest type, forest wetness and microhabitat) on the ptyctimous mites and on discovering their richness in broadleaf forests. Samples were collected from nine broadleaf forests in Western, Southern and Eastern Norway, in different climatic conditions, six forest types, three forest wetness states and eight microhabitats. Overall, 3341 ptyctimous mites were collected and their abundance differed significantly among the regions, forest types and microhabitats. Forest type turned out to be the most important factor, responsible for 24.5% of the total variation in the abundance of the ptyctimous mites. Other important factors were forest wetness and microhabitat. In total, 27 species, i.e., 87% of all ptyctimous mites known from before in Norway were found and the species richness was highest in the east and lowest in the west of the country. Atropacarus (Atropacarus) striculus was most common and most abundant; it made nearly 30% of all ptyctimous mites collected. On the other hand, a quarter of the species were represented by less than 10 specimens; most of these were new records for Norway. Among ten species discovered as new to Norway, four were also new to Fennoscandia. These findings confirm the unique character and high biological diversity of Norwegian broadleaf forests.publishedVersio

Mites (Oribatida and Mesostigmata) and vegetation as complementary bioindicators in peatlands

Vegetation is widely used in the assessment of the quality of peatlands, while the invertebrate fauna of peatlands is relatively poorly studied. We compared the bioindicator values of vegetation with two arthropod groups widespread in peatlands, saprophagous Oribatida (Acariformes) and predatory Mesostigmata (Parasitiformes) mites. Samples were collected from ecotones at the edges of peatland ponds in Poland, including four in near-natural condition (i.e., peatlands unaffected by human activity) and three in previously disturbed but now recovering peatlands. A set of abiotic parameters was measured at each site: pond area, mean annual temperature, annual precipitation, and water parameters (pH, conductivity, colour, total nitrogen, phosphorus, calcium, and organic carbon). Overall, 63,635 specimens of Oribatida and 448 of Mesostigmata were recovered in the sampling. Species richness of Oribatida (56 species) was higher than that of flora (46) and Mesostigmata (15). Vegetation was significantly associated with annual precipitation in the years 1998–2007 which accounted for 29.1 % of the variation in vegetation communities. Oribatida variability was significantly associated with the content of organic carbon in water accounting for 32.4 % of variation. In contrast, variation in the Mesostigmata was not significantly associated with any of the abiotic parameters. Vegetation at ponds in previously disturbed and now recovering peatlands had higher bush cover than at near-natural ponds and the pond in the cutaway peat had lowest moss cover and the highest number of associate species (i.e., species with wide tolerance not characteristic of the certain community). Mite communities did not differ consistently between near-natural and recovering peatlands. Sphagnum divinum Flatberg et Hassel was recorded from Poland for the first time.publishedVersio

Distribution and population characteristics of the soil mites Diapterobates notatus and Svalbardia paludicola (Acari: Oribatida: Ceratozetidae) in High Arctic Svalbard (Norway)

The Oribatida of High Arctic Svalbard are faunistically relatively well known, but the distribution, density, stage structure and other population parameters of most species are unknown. Here we focus on two ceratozetid species, Diapterobates notatus (Thorell, 1871) and Svalbardia paludicola Thor, 1930, and investigate the summer density, stage and sex structure, proportion of gravid females and the body size of these species in 33 locations and 11 vegetation classes of Svalbard. Diapterobates notatus occurred in all vegetation classes and at 29 locations, whereas S. paludicola occurred in only two vegetation classes and at three locations. The common occurrence of D. notatus in Svalbard may be due to: (1) cosmopolitan nature of this species which inhabits all vegetation classes but with a preference for open Dryas/Carex rupestris communities, (2) high biological potential (females were more abundant than males and carried 6–7 large eggs) resulting in a high proportion of juveniles, and (3) juvenile morphology which possesses long setae that may enhance passive dispersal by the wind. Adult body size was found to be greatest in the floristically diverse Arctic meadows. Svalbardia paludicola was particularly abundant in the Arctic meadow at Reinsdyrflya where juveniles were more plentiful than the adults. The nymphs of this species have shorter gastronotal setae than those of D. notatus which may limit their passive transport by the wind. Scutozetes clavatosensillus Ermilov, Martens & Tolstikov, 2013 was found in Mosselbukta (north Spitsbergen); this is the first observation of this species in Svalbard. Oribatid mites · Ecology · Stage and sex structure · Body siz

Morphological ontogeny of Galumna flagellata Willmann (Acari: Oribatida: Galumnidae)

The morphological ontogeny of Galumna flagellata Willmann, 1925 is described and illustrated. The juveniles of this species are light brown, with prodorsal setae of medium size or long and barbed, and bothridial seta clavate. The larva has 12 pairs of gastronotal setae, most of the medium size and barbed, of which seven (d-, l-series, h1) are located on gastronotal shield, nymphs have 15 pairs, mostly short setae, of which 10 (d-, l-, h-series, p1) are located on the gastronotal shield, setae of c-series are inserted on individual sclerites. In all juveniles, the typical galumnid humeral organ is absent, but a porose area is present in this location, which is unique in Galumna

Diverse mite communities (Acari: Oribatida, Mesostigmata) from a broadleaf forest in western Norway

Broadleaf forests are rare in Norway and they are considered one of the most biodiverse terrestrial habitats in Fennoscandia. These forests are poorly studied in terms of their acarofauna. Mites of two groups, Oribatida and Mesostigmata, were studied in a broadleaf forest in western Norway. In total, 6350 oribatid mites, representing 67 species (i.e., 25% of the known Norwegian species) and 559 mesostigmatid mites representing 22 species (9% of the species recorded from Norway) were collected. The mean densities of Oribatida and Mesostigmata were 454 and 40 individuals per 0.5 dm3, respectively. The most abundant member of Oribatida was Oribatula exilis (29% of Oribatida collected), while Zercon lindrothi made up 59% of Mesostigmata. Fifteen of the oribatid species were first records for Norway, including six new to Fennoscandia: Phthiracarus compressus, Suctobelbella arcana, S. hammerae, S. prominens, Campachipteria patavina and Liebstadia longior

Type of broadleaf forest matters most for ptyctimous mite communities (Acari, Oribatida) in Norway

We studied ptyctimous moss mites, which are characteristic of forest habitats, in Norwegian broadleaf forests considered as biodiversity hotspot areas in Fennoscandia. The study aimed to evaluate the effect of different factors (regional locality, annual precipitation, mean annual temperature, forest type, forest wetness and microhabitat) on the ptyctimous mites and on discovering their richness in broadleaf forests. Samples were collected from nine broadleaf forests in Western, Southern and Eastern Norway, in different climatic conditions, six forest types, three forest wetness states and eight microhabitats. Overall, 3341 ptyctimous mites were collected and their abundance differed significantly among the regions, forest types and microhabitats. Forest type turned out to be the most important factor, responsible for 24.5% of the total variation in the abundance of the ptyctimous mites. Other important factors were forest wetness and microhabitat. In total, 27 species, i.e., 87% of all ptyctimous mites known from before in Norway were found and the species richness was highest in the east and lowest in the west of the country. Atropacarus (Atropacarus) striculus was most common and most abundant; it made nearly 30% of all ptyctimous mites collected. On the other hand, a quarter of the species were represented by less than 10 specimens; most of these were new records for Norway. Among ten species discovered as new to Norway, four were also new to Fennoscandia. These findings confirm the unique character and high biological diversity of Norwegian broadleaf forests

Diverse mite communities (Acari: Oribatida, Mesostigmata) from a broadleaf forest in western Norway

Broadleaf forests are rare in Norway and they are considered one of the most biodiverse terrestrial habitats in Fennoscandia. These forests are poorly studied in terms of their acarofauna. Mites of two groups, Oribatida and Mesostigmata, were studied in a broadleaf forest in western Norway. In total, 6350 oribatid mites, representing 67 species (i.e., 25% of the known Norwegian species) and 559 mesostigmatid mites representing 22 species (9% of the species recorded from Norway) were collected. The mean densities of Oribatida and Mesostigmata were 454 and 40 individuals per 0.5 dm3, respectively. The most abundant member of Oribatida was Oribatula exilis (29% of Oribatida collected), while Zercon lindrothi made up 59% of Mesostigmata. Fifteen of the oribatid species were first records for Norway, including six new to Fennoscandia: Phthiracarus compressus, Suctobelbella arcana, S. hammerae, S. prominens, Campachipteria patavina and Liebstadia longior

High Diversity of Mites (Acari: Oribatida, Mesostigmata) Supports the High Conservation Value of a Broadleaf Forest in Eastern Norway

Broadleaf forests are critical habitats for biodiversity and this biodiversity is in turn essential for their proper functioning. Mites (Acari) are a numerous and functionally essential component of these forests. We report the diversity of two important groups, Oribatida and Mesostigmata, in a broadleaf forest in Eastern Norway which is considered to be a biodiversity hotspot. Eighteen samples, each 500 cm3, were collected from diverse microhabitats (moss on ground, lichens on tree twigs lying on ground, moss on tree trunks at ground level, moss on tree trunks 1.5 m above ground, moss on decaying stump, moss on decaying log, and decaying wood from trees) from which 10,843 specimens and 95 species from 32 families of Oribatida, and 655 specimens of 34 species from 14 families of Mesostigmata were found. Only 30% of the species were previously recorded in broadleaf forests in Western Norway. Oribatid communities on decaying stump and in lichens were distinct from the other communities, while mesostigmatid communities on tree trunks (both at ground level and 1.5 m above ground) and in lichens differed most from other communities. Over 30% of the species were found in only a single microhabitat. Twenty-three species and the genus Zerconopsis are reported from Norway for the first time. Six records are also new to Fennoscandia, including (Oribatida) Coronoquadroppia monstruosa, Eueremaeus valkanovi, Ramusella furcata, and (Mesostigmata) Dendrolaelaps rectus, D. multidentatus, and D. tenuipilus. In addition, several rare species were detected, e.g., Achipteria magna, Oribotritia berlesei, and Subiasella quadrimaculata, and two were found in their northernmost locality (O. berlesei, E. valkanovi). These results confirm the unique character and high conservation value of the studied forest in Norway, Fennoscandia and at a European scale