This species is very common inside houses in Great Britain, and is sometimes found outdoors in the vicinity of houses in the south of the country. It is often seen walking on walls or the ceiling, or even in the bath. Its body is largely black, and around 10 mm in length. It should not be confused with the large spdiers more often seen walking on carpets. These are most likely to be Tegenaria sp.
Head and chelicerae of Scotophaeus blackwalli
Chelicerae of a female Scotophaeus blackwalli, viewed from the side nearest the mouthparts
Left Pedipalp (male sexual organ) of Scotophaeus blackwalli
Epigyne (female sexual organ) of Scotophaeus blackwalli
Spinnerets of Scotophaeus blackwalli
Tarsus of Scotophaeus blackwalli. Note the bristly underside (the scoupla), which almost hides the tarsal claws.
Light micrograph of the same epigyne as above, for comparison
Pedipalp of a female Scotophaeus blackwalli
Scopula hair from a tarsus of Scotophaeus blackwalli, at high magnification