T
he presence stout spines on the coxae of the 15th (last) leg pair of large brown Lithobius species indicates the presence of a species other than the ubiquitous L. forficatus. Ideally view from below.
L. pilicornis is unique in having both 15 VmC and 15 VaC.
L. piceus has just 15 Vac.
Importantly, the ubiquitous L. forficatus lacks both spines.
L. tricuspis, a small brown species, may sometimes have 15 Vac, but all other British and Irish Lithobius species have neither.
If you don't check you won't find!