ARACHNIDA > ARANEAE > Agelenidae > Eratigena and Tegenaria

The Eratigena and Tegenaria species are collectively known as 'house spiders' although only five are actually synanthropic, the remainder favouring more natural habitats. Determining the genera is usually dependent on the presence or not of annulations on the legs as even feint rings indicate Tegenaria. However, juvenile Eratigena can also show feint annulations so a degree of caution is needed.

Identification to species of the three Eratigena house-dwelling species Eratigena atrica, Eratigena duellica and Eratigena saeva is not possible without microscopic examination so they should always be recorded as Eratigena sp. in the atrica complex, even though Eratigena atricia is by far the rarest of the three in Britain. The most common and widespread species is Eratigena duellica, formerly Tegenaria gigantea, known as the Giant House Spider due to its size and very long legs, which are characteristic of the group such that the name is applied to the complex as a whole.

The only other Eratigena species that may be encountered locally is Eratigena agrestris, which is an uncommon spider more likely to be found under stones or hidden in crevices on scrubby wasteland areas or brownfield sites.

The two synanthropic Tegenaria species are Tegenaria domestica, the Common House Spider, and Tegenaria parietina, the Cardinal Spider, which is a scarce southern species more often found in old buildings. Tegenaria domestica differs from the house-dwelling Eratigena species in being smaller and paler, with some individuals almost completely lacking the darker abdominal markings.

Tegenaria silvestris is effectively the final species of interest as the two remaining Tegenaria species are both extremely rare. It's primarily a woodland spider that favours damp locations under stones, fallen branches or logs. It has similar markings to the Eratigena species, but with distinct leg annulations as previously noted.

Although all of the following individuals have been labelled as Eratigena sp. as they cannot be distinguished, I would have thought that those found in the New Forest and at Blashford Lakes could well be Tegenaria silvestris simply due to habitat, because as far as I can see none of the other species occur in woodlands. However, I've been told that the three darker specimens are all immatures and even though there's feint indications of annulations on the legs there's absolutely no way of knowing until the spider has fully matured. I've also seen photos of adult Tegenaria silvestris where the banding is very clear, but then I've seen a photo of Tegenaria parietina that doesn't appear to have leg annulations. And, to me, the second photo of the large chap with the grey legs and contrasting dark femora, looks so distinctive that I'm amazed it can't be identified.

So, all in all, I find these two genera really confusing.

Updated, Nov.23 (v.2)