''Clubiona subsultans'', the Caledonian sac spider, is a spider from the family

Clubionidae The sac spiders of the family Clubionidae have a very confusing taxonomic history. Once, this family was a large catch-all taxon for a disparate collection of spiders, similar only in that they had eight eyes arranged in two rows and conical anter ...

with a

Palearctic The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Si ...

distribution.

Description

The body length of female ''Clubiona subsultans'' varies from 5–7 mm, that of males from 5–9 mm. The

tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

apophysis Apophysis may refer to: *A tubercle (bone) *Apophysis (spider) This glossary describes the terms used in formal descriptions of spiders; where applicable these terms are used in describing other arachnids. Links within the glossary are shown . ...

is pointed and has 2 barbs. The

prosoma The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''ce ...

is golden-brown, the chelicerae are brownish and the legs yellow. The abdomen is reddish brown with yellow spots and a black median band with white arc-lines.

Habitat and ecology

''Clubiona subsultans'' is normally found under stones and bark and in moss and litter, mostly in coniferous forests. In Britain it is called Caledonian sac-spider because the native

Scots pine ''Pinus sylvestris'', the Scots pine (UK), Scotch pine (US) or Baltic pine, is a species of tree in the pine family Pinaceae that is native to Eurasia. It can readily be identified by its combination of fairly short, blue-green leaves and or ...

forest is the normal habitat. ''Clubiona subsultans'' is associated with Caledonian pine woods, where it has been found under bark, on branches, in pine litter, among young pines, and on

juniper Junipers are coniferous trees and shrubs in the genus ''Juniperus'' () of the cypress family Cupressaceae. Depending on the taxonomy, between 50 and 67 species of junipers are widely distributed throughout the Northern Hemisphere, from the Arcti ...

growing as an under-storey within a pine wood. Recently it was found to have been the commonest spider caught in artificial nestbox traps which were put out in

Abernethy Forest Abernethy Forest is a remnant of the Caledonian Forest in Strathspey, in the Highland council area of Scotland. It lies within the Cairngorms National Park, close to the villages of Nethy Bridge, Boat of Garten, and Aviemore. The forest is an RSP ...

to survey for the bee ''

Osmia uncinata ''Osmia uncinata'', the pinewood mason bee, is a species of solitary bee from the family Megachilidae It is an Arctic-alpine species which is found in the northern Palearctic, in the United Kingdom it is a Biodiversity Action Plan priority spec ...

''. Adult male and female spiders have been found in June, the males also in September.

Distribution

''Clubiona subsultans'' has a Palearctic distribution. In Europe it is found in northern and central Europe. In

Great Britain Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It is ...

this species is confined to

relict A relict is a surviving remnant of a natural phenomenon. Biology A relict (or relic) is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas. Geology and geomorphology In geology, a r ...

patches of Caledonian Forest in north-central

Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to th ...

, giving rise to the species

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contra ...

of Caledonian sac spider.

Conservation

In Scotland ''Clubiona subsultans'' is threatened by the loss of Caledonian pine forest, especially through the planting of Scots pine and non-native conifers in large blocks, which is sometimes preceded by the clear-felling of the native pine. To conserve this spider the management of the forest should be aimed at conserving the pine and other native trees. The natural regeneration of Scots pine should be allowed to proceed to give the typical open forest structure of the Caledonian forest. If regeneration is too dense then early thinning of the saplings may be needed to create glades. The main site at Abernethy is now a reserve of the

Royal Society for the Protection of Birds The Royal Society for the Protection of Birds (RSPB) is a charitable organisation registered in England and Wales and in Scotland. It was founded in 1889. It works to promote conservation and protection of birds and the wider environment throu ...

and its primary aim is to develop a self-sustaining native pine forest over the whole potential woodland area.

References

{{Taxonbar, from=Q1761723 Clubionidae Palearctic spiders Spiders described in 1875