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In recent years, the Noble false widow spider Steatoda nobilis (Thorell, 1875) has expanded its range globally and may represent a potential threat to native ecosystems and public health. Increasin...

The noble false widow spider Steatoda nobilis originates from the Macaronesian archipelago and has expanded its range globally. Outside of its natural range, it may have a negative impact on native wildlife, and in temperate regions it lives in synanthropic environments where it frequently encounters humans, subsequently leading to envenomations. S. nobilis is the only medically significant spider in Ireland and the UK, and envenomations have resulted in local and systemic neurotoxic symptoms similar to true black widows (genus Latrodectus). S. nobilis is a sister group to Latrodectus which possesses the highly potent neurotoxins called &alpha, latrotoxins that can induce neuromuscular paralysis and is responsible for human fatalities. However, and despite this close relationship, the venom composition of S. nobilis has never been investigated. In this context, a combination of transcriptomic and proteomic cutting-edge approaches has been used to deeply characterise S. nobilis venom. Mining of transcriptome data for the peptides identified by proteomics revealed 240 annotated sequences, of which 118 are related to toxins, 37 as enzymes, 43 as proteins involved in various biological functions, and 42 proteins without any identified function to date. Among the toxins, the most represented in numbers are &alpha, latrotoxins (61), &delta, latroinsectotoxins (44) and latrodectins (6), all of which were first characterised from black widow venoms. Transcriptomics alone provided a similar representation to proteomics, thus demonstrating that our approach is highly sensitive and accurate. More precisely, a relative quantification approach revealed that latrodectins are the most concentrated toxin (28%), followed by &alpha, latrotoxins (11%), &delta, latroinsectotoxins (11%) and &alpha, latrocrustotoxins (11%). Approximately two-thirds of the venom is composed of Latrodectus-like toxins. Such toxins are highly potent towards the nervous system of vertebrates and likely responsible for the array of symptoms occurring after envenomation by black widows and false widows. Thus, caution should be taken in dismissing S. nobilis as harmless. This work paves the way towards a better understanding of the competitiveness of S. nobilis and its potential medical importance.

The noble false widow Steatoda nobilis is the only medically significant spider known to occur in the British Isles and Ireland, with a single case of steatodism ever reported from Great Britain. We present here five new cases of envenomations by S. nobilis, three from Ireland and two from Great Britain and describe symptoms not previously reported for the genus Steatoda.Four adult males and one adult female with confirmed S. nobilis bites reported their symptoms to the authors. General practitioner chart was obtained for case #3. In all five cases, envenomations were immediately followed by a sharp and prolonged onset of pain, mild to extensive erythema and localised to extensive swelling around the bite site. Additional symptoms include moderate to intense pruritus, vasodilation of the capillaries around the bite site and a possible minor necrotic wound.In all cases, symptoms subsided within 48-72 h and no further complications were reported. Envenomations by S. nobilis seem to produce symptoms similar (but not identical) to those previously reported from other Steatoda sp. Considering their benign outcome, envenomations by S. nobilis should still be regarded as of moderate medical importance, requiring monitoring and pain management strategies.

Summary In this work we present new records of Steatoda nobilis (Thorell, 1875), a species originally from Madeira and the Canary Islands, for the Italian mainland and Sardinia. We discuss local ecology and ethology and provide brief genital and morphological descriptions of both sexes.

A young woman was bitten on the shoulder by a female Steatoda nobilis spider, in Worthing on the south coast of England. She noticed intense radiating pain, local sweating (indicating parasympathetic stimulation) and feverishness. This immigrant species from the Canary Islands has established itself along the south coast of England in recent years. Like the related Mediterranean species S. paykulliana, S. nobilis may be of medical importance and deserves further study.