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New Record of the Rare Phytoseiid Mite (Parasitiformes: Phytoseiidae) from Poland and Description of Unknown Male
The Diversity of Arachnid Assemblages on the Endemic Tree Zelkova abelicea (Ulmaceae): An Evaluation of Fragmentation and Connectivity in Crete (Greece)
Zelkova abelicea is an endemic tree growing only on eight mountain stands on the Greek island of Crete. The aim of this study was to determine the structure of the assemblages and analyze the diversity of the arachnid assemblages living on Zelkova abelicea, an endemic tree species in Crete. Material for the analyses was collected from tree trunks, oftentimes covered by bryophytes or lichens. In the examined material, 85 taxa were recorded. The most numerous groups represented in the analyzed material were Acari, including representatives of the orders Mesostigmata (78 ind. of 18 spp.) and Oribatida (1056 ind. of 51 spp.). In the order Mesostigmata the species represented by the highest numbers of specimens were Onchodellus karawaiewi (15 individuals) and Hypoaspisella sp. (13), which is probably a species new to science. In turn, representatives of the order Oribatida were much more numerous, with Zygoribatula exilis (284) and Eremaeus tuberosus (210) being identified in the largest numbers. Among the eight sampled localities, Gerakari (646 ind. and 50 spp.) and Omalos (409 ind. and 43 spp., respectively) had by far the richest assemblages. Statistical analyses confirmed the highly diverse character of the arachnid assemblages at the individual sites, which is a consequence not only of the varied numbers of arachnids found, but also of the presence of very rare species, such as Androlaelaps shealsi, Cosmolaelaps lutegiensis or Hoploseius oblongus. These results highlight the high species diversity of the arachnids found on Z. abelicea but also suggest the lack of connectivity between the isolated and fragmented forest stands on Crete.
Impact of Biogenic Structures of the Soil-Nesting Ants Lasius niger and Lasius flavus on the Soil Microarthropod Community in Urban Green Spaces
Organisms that physically modify their environment, known as ecosystem engineers, can influence resource availability, species interactions and the structure of soil communities. However, the specific effect of ecosystem engineers like ants on the abundance and diversity of non-engineering soil organisms remains understudied. To address this knowledge gap, we conducted a survey of a multi-taxon belowground community of soil microarthropods—Collembola, Mesostigmata, Oribatida and Actinedida—in urban areas, comparing nest mounds of the ant species Lasius niger and Lasius flavus with areas without ant-nesting activity (control). We hypothesised differences in abundance and distribution patterns of different soil microarthropod taxa between ant mounds and the control soil. We also hypothesised that ant-induced soil disturbance is species-specific, and may result in different patterns of diversity and composition of soil microarthropod assemblages within trophic levels, such as among detritivores (e.g., Collembola) and predators (e.g., Mesostigmata). Our results reveal how ecological filters shape different soil microarthropod groups’ responses to ant-driven changes in their environment. As we expected, soil disturbance caused by ant nest-building activity significantly influenced the abundance, distribution patterns and diversity of soil microarthropods, especially in the assembly of detritivorous—but not predatory—guilds of soil microarthropods.
The impact of marine vertebrates on polar terrestrial invertebrate communities
AbstractMarine birds and pinnipeds which come to land to breed, rest and moult are widely known to fertilize adjacent terrestrial ecosystems, with cascading effects on vegetation and other trophic levels. We provide a synthesis of the consequences of allochthonous nutrient enrichment for terrestrial invertebrate communities within and around marine vertebrate aggregation sites and nutrient sources in the High Arctic and Continental and Maritime Antarctic, the most nutrient-poor and environmentally extreme parts of the polar regions. Using a combination of literature review (identifying 19 articles from the Arctic Svalbard archipelago and 12 from different Antarctic locations) and new analyses of available datasets of springtail, mite and tardigrade community composition, we confirmed that terrestrial invertebrate abundance and species richness tended to increase, and their community compositions changed, as a result of marine vertebrate fertilisation in both polar regions. These changes were significantly greater on talus slopes enriched by kittiwakes, guillemots and little auks in the Arctic, as compared to the edges of penguin colonies in the Antarctic. Both these habitat areas were typically abundantly vegetated and provided the most favourable microhabitat conditions for terrestrial invertebrates. The most heavily disturbed and manured areas within Antarctic penguin rookeries and seal wallows, generally on flat or gently sloping ground, were typically characterised by extremely low invertebrate diversity. In the Arctic, only sites directly beneath densely-occupied bird cliffs were to some extent comparably barren. Invertebrate responses are dependent on a combination of vertebrate activity, local topography and vegetation development.