Eratigena atrica
Eratigena atrica

I have noticed that some 31 pan-species listers have recorded the scarce house spider Eratigena atrica. Now I am sure some might have recorded this correctly but this is a gen det job to get to species and there are two far more closely related species that occur in houses, which are exactly the same size. As top lister for spiders, Eratigena atrica is not a species I have seen, which gives an idea of how uncommon it is.

The reason for this situation is almost certainly because the UKSI has Eratigena atrica listed as Giant House Spider. Of course, this vernacular could easily be used for the other two extremely common species: E. duellica which is universal but less common in the west and E. saeva, which is more regional and commoner in the west. The name Giant House Spider is not used by the Spider and Harvestman Recording Scheme (SRS) or in Britain's Spiders (WILDGuides): A Field Guide. The Internet is also saturated with this mistake and I have seen house spiders named as this species for many years incorrectly by wildlife charities etc. I am not sure if this is a legacy of a scientific name change/split. I think it will be best if we remove the vernacular from the website and we will encourage the UKSI to do the same.

Unless you have identified this spider by its genitalia, it’s highly likely that you have seen one of the other species, so in these cases I suggest you either change it or better still, remove it until you encounter one you can get to species.

Here are the three distribution maps taken from the SRS website. As can be seen, Eratigena atrica appears to be declining away from its north-east stronghold.

Desc
Eratigena atrica
Desc
Eratigena duellica
Desc
Eratigena saeva
 

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