Stanisław Seniczak

Community Structure of Oribatid and Gamasid Mites (Acari) in Moss-Grass Tundra in Svalbard (Spitsbergen, Norway)

Abstract The mite fauna of patches of High Arctic moss-grass tundra of Svalbard in Petuniabukta, Billefjord (moss, grasses, Salix polaris, bare soil), and adjacent to Vestpynten, Adventfjord (moss, moss mixed with grasses, Cassiope tetragona, S. polaris), were investigated. Our aim was to describe the mite fauna of this tundra with particular focus on the stage structure that is rarely investigated. We observed that the oribatid mites were distinctly more abundant and richer in species (22) than the gamasid mites (7) and their density and diversity varied between vegetation and location. Species diversity of Oribatida and Gamasida and the Shannon H′ index of mite communities were low, and Liochthonius sellnicki or Tectocepheus velatus dominated the Oribatida and Oppiella translamellata and Diapterobates notatus were relatively abundant, while the Gamasida were dominated by Arctoseius multidentatus, with Zercon forsslundi and Z. solenites relatively abundant. The juvenile densities of the Oribatida were usually greater than adults. Eniochthonius minutissimus and Metabelba sp. are new records for Svalbard.

Morphology of juvenile stages of three species of Scheloribatidae (Acari: Oribatida)

Abstract. The morphology of juvenile stages and ontogeny of Scheloribates holsaticus (Weigmann, 1969), S. initialis (Berlese, 1908), and S. pallidulus (C. L. Koch, 1841) were investigated. The juveniles of these species have excentrosclerites at similar gastronotal setae (c2, la, lp, and h1 in larva, and C2, la, lp, h-series, and P1 in nymphs), and solenidion &ohgr;1 on tarsus I strongly curved outwards, which are typical of Scheloribatidae, but they differ by body size and the shape of most gastronotal setae. The successive juvenile stages of S. holsaticus are the largest, while those of S. pallidulus are the smallest. The former species has most gastronotal setae barbed, while S. initialis and S. pallidulus have them smooth. The latter species has these setae thinner and more curved than other species, and pliable in distal parts. The adult of all these species have notogastral sacculi, but S. holsaticus has 13 pairs of notogastral setae, including pairs C2 and d-series, while other species have 10 pairs of setae, including pair C2.

Oribatid mites (Acari, Oribatida) of pine and cypress litter in selected habitats of Sicily (Italy)

Abstract Oribatid mites live in the soil or plant matter and usually feed on living and dead plant or fungal material, lichens, carrion, or some species are rarely predatory. Oribatid communities were investigated in litter under pine and cypress trees in selected locations in Sicily: Etna slopes (near Rifugio Sapienza and near Castiglione di Sicily), coastal town Giardini Naxos, Archaeological Museum in Agrigento, and Archaeological Park in Sagesta. The most abundant and diverse oribatid mites lived in cypress litter in Agrigento and on Etna slope. The lowest numbers of individuals and species were recorded in pine litter in Agrigento. In the oribatid mite communities, only 1-3 species were abundant, so the values of Shannon H’ index, and Pielou EPielou and Hurlbert EHurlbert evenness indices were rather low. Their values were the highest in pine litter near Rifugio Sapienza, located nearest to the crater of Etna, while the lowest in pine litter in Agrigento. The former habitat was rich in oribatid mites and species, with a large participation of small species, like Suctobelbella subcornigera, Brachychthonius impressus, and Liochthonius simplex, which made up nearly 63% of the total number of oribatid mites within that habitat. In other habitats, usually Oribatula propinqua dominated, but in pine and cypress litter in Giardini Naxos, Oppiella nova and Ramusella clavipectinata were the most abundant, respectively. Among oribatid mites, adults usually dominated, but Adrodamaeus femoratus, Aphelacarus acarinus, Brachychthonius impressus, Liochthonius simplex, Cosmochthonius reticulatus, Metabelba pulverulenta and Pilogalumna crassiclava were rich in juveniles.

Oribatid mites (Acari, Oribatida) of yew, cypress and pine litter in southern Italy

Abstract Oribatid mite communities were investigated in southern Italy in litter under yew, pine and cypress trees. These mites achieved the highest density in yew and cypress litter in a park in the inland town of Caserta, and the lowest density in pine litter at the coast of Capo Vaticano. In these mite communities, only 1-4 species were abundant, so the Shannon index H’ was rather low. The density of oribatid mites, species number, and dominance structure depended greatly on the kind of litter. The most abundant and common was Zygoribatula propinqua, but the highest density in yew litter was achieved by Oribatella superbula. In oribatid mite communities, the juveniles usually dominated, but the age structure of species greatly depended on the kind of litter.