The spider family Plectreuridae includes just 31 described species in two genera (Platnick 2014; Ubick 2005 notes that additional undescribed Plectreurys species are known in collections), with nearly all species known from Mexico or the southwestern United States.
Plectreurids are sedentary hunters that are most abundant in deserts and other arid regions, but they also range into mixed broadeaf and coniferous forests. Their high clypeus and and tall, forward-slanting chelicerae give these spiders a distinctive face. Plectreurids are ground spiders and build tangle webs with retreats under rocks, fallen bark, and other ground litter. Males leave their retreats when mature and may be seen wandering at night. Both sexes can be collected in pitfall traps. Females construct lacy cocoon-like retreats for guarding the egg sac. In captivity, plectreurids are easily reared on a diet of flies and may live for several years.
At various times, these spiders have been included in the family Sicariidae or Scytodidae. Gertsch (1949) supported Nathan Banks' early recognition of this group at the family level and revised the family (Gertsch 1958) (Ubick 2005 notes that this family has not been studied since and is in need of revision).
(Ubick 2005; Bradley 2013)
Plectreuridae, also called plectreurid spiders, is a small spider family confined to the Southwestern United States, Mexico,[1] and the Caribbean.[2] Only two living genera are known—the nominate genus Plectreurys and Kibramoa. In the past, the family was more widespread, with the Jurassic genus Eoplectreurys known from China, the Eocene Palaeoplectreurys baltica from Baltic amber and the Miocene Plectreurys pittfieldi from Dominican amber.[3]
These ecribellate, haplogyne spiders build haphazard webs under rocks and dead cacti. Adult males can be found wandering at night.[2] Relatively little is known of their biology. Unlike the sicariids, scytodids, and diguetids, to which they are most closely related, they have eight eyes. In appearance females of Plectreurys resemble those of the larger species of the cribellate Filistatidae. They differ in their eye arrangement and in having the femurs on the first pair of legs bowed. Also, in relativity to body size, they have the largest recognized venom glands, with their multilobular glands taking up up to 50% of their body. [4]
As of April 2019, the World Spider Catalog accepts the following genera:[5]
Plectreuridae, also called plectreurid spiders, is a small spider family confined to the Southwestern United States, Mexico, and the Caribbean. Only two living genera are known—the nominate genus Plectreurys and Kibramoa. In the past, the family was more widespread, with the Jurassic genus Eoplectreurys known from China, the Eocene Palaeoplectreurys baltica from Baltic amber and the Miocene Plectreurys pittfieldi from Dominican amber.
These ecribellate, haplogyne spiders build haphazard webs under rocks and dead cacti. Adult males can be found wandering at night. Relatively little is known of their biology. Unlike the sicariids, scytodids, and diguetids, to which they are most closely related, they have eight eyes. In appearance females of Plectreurys resemble those of the larger species of the cribellate Filistatidae. They differ in their eye arrangement and in having the femurs on the first pair of legs bowed. Also, in relativity to body size, they have the largest recognized venom glands, with their multilobular glands taking up up to 50% of their body.
