Tetragnatha extensa

Tetragnatha extensa
T. extensa on Philadelphus coronarius
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Class:	Arachnida
Order:	Araneae
Infraorder:	Araneomorphae
Family:	Tetragnathidae
Genus:	Tetragnatha
Species:	T. extensa
Binomial name
Tetragnatha extensa (Linnaeus, 1758)
Subspecies
Tetragnatha extensa brachygnatha Thorell, 1873 – Sweden, Russia Tetragnatha extensa maracandica Charitonov, 1951 – Iran, Russia, Central Asia Tetragnatha extensa pulchra Kulczynski, 1891 – Hungary

Tetragnatha extensa is a species of spider found across the Northern Hemisphere. It has an elongate body, up to 11 mm (0.43 in) long, and adopts a straight line posture when alarmed. It lives on low vegetation in damp areas, and feeds on flying insects which it catches in its web.

T. extensa has an elongated, cream-coloured body.^[1] Males are smaller than females, at around 9 millimetres (0.35 in) body length, compared to 11 mm (0.43 in) for females.^[2] The four pairs of legs are very long,^[1] and are dark yellow.^[3] The carapace, which is around 1.8–2.6 mm long and 1.1–1.7 mm wide, is orange or dark yellow.

The colouring of T. extensa is quite variable,^[4] ranging from creamy-yellow to green.^[2] On the underside, there is a thick black central band, with a silvery band on either side.^[3]

T. extensa is distinguished from other members of the genus Tetragnatha by the minute curved tip of the male's conductor (part of the pedipalp), and the form of the female's spermatheca.^[3]

T. extensa has a wide distribution across the Northern Hemisphere (Holarctic).

In North America, it is found from Alaska to Newfoundland, and its range extends south to Washington, Colorado and Pennsylvania.^[3] The species has a broad ecological range, having been found at the tree line in the Rocky Mountains.

It is found in coastal vegetation in Europe.^[3] T. extensa is found throughout the United Kingdom,^[2] where it is the commonest species of Tetragnatha,^[4] and one of the commonest spiders.^[1] It is also found in Madeira.

Tetragnatha extensa is found on low-growing vegetation, usually in damp areas.^[1] It feeds on insects, including mosquitos, midges and moths, which it catches in its loosely constructed web.^[1] When alarmed,^[2] it will sit along a plant stem, a blade of grass or the central vein of a leaf, with its four front legs pointing forwards, and its four back legs pointing backwards for camouflage.^[1] T. extensa is able to walk on the surface of water, where it can move faster than on land.^[5]

Adults are seen between May and September in the United Kingdom,^[2] and between May and July in Alaska.^[3] There is little courtship, and the male and female lock jaws, possibly to prevent the female from eating the male before mating.^[5] The egg sacs are globular and covered with grey tufted silk,^[3] resembling a bird dropping,^[5] and are pressed against a plant stem.^[3] Overwintering occurs in the form of early-instar spiderlings.^[3]

Tetragnatha extensa was first given a binomial by Carl Linnaeus in his Systema Naturae of 1758, the starting point of zoological nomenclature.^[6] In that work, it was included in the genus Aranea (now Araneus). T. extensa is a very common, widespread and variable species, and a number of synonyms have been published:^[6]

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