Systematic revision of the Savignia genus group (Araneae: Linyphiidae: Erigoninae) with notes on their cephalic lobe evolution

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  Systematic revision of the Savignia genus group (Araneae: Linyphiidae: Erigoninae) with notes on their cephalic lobe evolution Abstract The Savignia genus group includes nine morphologically complex yet similar genera where species were assigned based mainly on the cephalic lobes. Among these genera, males of Diplocephalus Bertkau, 1883, Savignia Blackwall, 1833 and Araeoncus Simon, 1884 show some of the most extraordinary cephalic lobes among dwarf spiders (Linyphiidae, Erigoninae). In this study we undertake the first phylogenetic analysis of the Savignia genus group. We use 269 morphological characters (175 newly defined) and 70 taxa (59 ingroup taxa) to reconstruct the relationships and evolutionary trends of cephalic lobes in this lineage. Our findings show that cephalic lobes with varying shapes and sizes appear in several Savignia genus group lineages, highlighting that it is not a good diagnostic character. The high support in several clades allows the redefinition of t...

Survey of Synanthropic Spiders in Ireland Reveals Expansion and Dominance of the Invasive Noble False Widow Steatoda nobilis in Urban Habitats (Araneae: Theridiidae)

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Survey of Synanthropic Spiders in Ireland Reveals Expansion and Dominance of the Invasive Noble False Widow Steatoda nobilis in Urban Habitats (Araneae: Theridiidae)

ABSTRACT

Rapid urbanisation has led several spider species to adapt to synanthropic microhabitats and establish large populations outside of their native ranges. In Ireland, the establishment and widespread distribution of the Noble false widow spider Steatoda nobilis (Araneae: Theridiidae) (Thorell, 1875) has raised questions about its impact on native spider populations across the country. Through an extensive field survey of six urban centres over an 11-month period, we sought to establish population demographics for S. nobilis and other synanthropic spiders in Ireland for the first time. We surveyed fence microhabitats for both spider abundance and diversity to determine the influence of variables such as prey availability and climate. Of the 20 identifiable species observed, S. nobilis and the missing sector orb weaver Zygiella x-notata (Clerck, 1757) typically made up more than 80% of the spider abundance regardless of location surveyed, including two new Irish counties where S. nobilis had previously not been recorded but is now well established (Co. Mayo and Co. Sligo). Our results also indicated that the diversity of synanthropic spiders is significantly affected by seasonality and prey availability, but largely unaffected by daily weather conditions.

Collier, B.L., Leonard, D., Lyons, K., Dunbar, J.P., Lawton, C. and Dugon, M.M. (2026), Survey of Synanthropic Spiders in Ireland Reveals Expansion and Dominance of the Invasive Noble False Widow Steatoda nobilis in Urban Habitats (Araneae: Theridiidae). Ecol Evol, 16: e73193. https://doi.org/10.1002/ece3.73193