Gnathonarium dentatum is a common linyphiid within the UK, inhabiting wet environments. This species is interesting in that the carapace projects beyond the clypeus in both sexes, and the male has a tooth-like process on the chelicerae (that presumably acounts for its species name). Both these features may be observed in the first image below.
Head and chelicerae of male Gnathonarium dentatum. The tooth-like processes on the chelicerae may be seen clearly.
Head and chelicerae of female Gnathonarium dentatum. Note the absence of tooth-like processes.
Left pedipalp (male sexual organ) of Gnathonarium dentatum
Carapace of a male Gnathonarium dentatum. Note the more conventional appearance compared with the males with raised lobes in some species.
Carapace of a female Gnathonarium dentatum
Lateral view of the carapace of a female Gnathonarium dentatum