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As glaciers retreat, their forelands represent “natural laboratories” for the study of primary succession. This review describes how certain arthropods conquer pristine ground and develop food webs before the establishment of vascular plants. Based on soil samples, pitfall traps, fallout and sticky traps, gut content studies, and some unpublished data, we compare early arthropod succession on glacial forelands of northern Europe (Iceland, Norway including Svalbard, and Sweden) and of the Alps (Austria, Italy). While macroarthropod predators like ground beetles (Coleoptera: Carabidae), harvestmen (Arachnida: Opiliones), and spiders (Arachnida: Araneae) have usually been considered as pioneers, assumed to feed on airborne prey, this review explains a different pattern. Here, we highlight that springtails (Collembola), probably feeding on biofilm made up of algae or cyanobacteria, are super-pioneers, even at high altitudes and under arctic conditions. We also point out that macroarthropod predators can use locally available prey, such as springtails or non-biting midges (Diptera: Chironomidae). Pioneer arthropod communities vary under different biogeographical and climatic conditions. Two pioneer food webs, from northern Europe and the Alps, respectively, differed in structure and function. However, certain genera and orders were common to both. Generalists and specialists live together in a pioneer community. Cold-adapted specialists are threatened by glacier melting.

22With 128 described species and 5 subspecies, the spider genus Troglohyphantes (Araneae, 23 Linyphiidae) is a remarkable example of species diversification in the subterranean environment. In 24 this paper, we conducted a systematic revision of the Troglohyphantes species of the Italian Alps, 25 with a special focus on the Lucifuga complex, including the description of two new species (T. 26 lucifer n. sp. and T. apenninicus n. sp). In addition, we provided new diagnostic drawings of the 27 holotype of T. henroti (Henroti complex) and established three new synonymies within the genus. 28The molecular analysis of the animal DNA barcode confirms the validity of this method of 29 identification of the Alpine Troglohyphantes and provides additional support for the morphology-30 based species complexes. Finally, we revised the known distribution range of additional 31Troglohyphantes species, as well as other poorly known alpine cave-dwelling spiders. 32 33

In this contribution we present the Catalog of Italian spiders, produced on the base of the available scientific information regarding spider species distribution in Italy. We analysed an amount of 1124 references, resulting in a list of 1670 species and subspecies, grouped in 434 genera and 53 families. Information on spider biodiversity in Italy has increased rapidly in the last years, going from 404 species at the end of XIX century, to 1400 in the 1990s, to the current 1670. However, the knowledge on the distribution of the Italian species is far from being complete and it seems likely that there are still new species to be found or described. The Italian spider fauna is characterized by the presence of a relevant number of endemic species (342). Concerning families, Linyphiidae show the highest number of species (477) and the highest number of endemics (114). Gnaphosidae (166) and Salticidae (144) follows in terms of species richness, while Dysderidae (72) and Agelenidae (38) follows as total number of endemics. Information regarding the regional distribution revealed great unbalance between Northern and Southern Italy, with very scarce records for some regions in the South. This work is accompanied by an online version freely available online at www.araneae.it, where all information is thoroughly detailed and regularly updated by the authors. Besides spiders, we also provide, the species lists of other Arachnid orders occurring in Italy (Opiliones, Palpigradi, Pseudoscorpionida, Scorpiones, Solifugae). The lists and the associated details are available in a dedicated section of the online version of the Catalog.