''Nuctenea umbratica'', the walnut orb-weaver spider, is a species of spider in the family

Araneidae Orb-weaver spiders are members of the spider family Araneidae. They are the most common group of builders of spiral wheel-shaped webs often found in gardens, fields, and forests. The English word "orb" can mean "circular", hence the English name ...

Name

The species name ''umbratica'' means "living in the shadows" in

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

Description

The walnut orb-weaver spider is very wide and flattened, with a leathery skin. Its color ranges from red brown and grey brown to black, with a dark, yellowish to yellow-greenish leaf-like flecked marking on its

opisthosoma The opisthosoma is the posterior part of the body in some arthropods, behind the prosoma ( cephalothorax). It is a distinctive feature of the subphylum Chelicerata (arachnids, horseshoe crabs and others). Although it is similar in most respects ...

, where small dents are visible. These are the onsets of muscles that flatten the abdomen. Female ''N. umbratica'' can reach up to 15 mm in size; the males grow only up to 8 mm. The spider hides during the day outside of buildings in wall crevices or under loose bark. They are very common in Central Europe; females occur all year, while males appear mostly during the summer. This spider has a flattened body, helping it to secrete itself in cracks and crevices. Walnut orb-weaving spiders are capable of concealing themselves in very confined spaces. This tends to act as a defensive advantage and increases the number of locations an orb-web can be effectively constructed. In the evening the spider constructs an orb-web that can be up to 70 cm in diameter. A signaling thread leads from the web to her hiding place. After dusk she sits in the web's center.

Distribution and subspecies

* ''Nuctenea umbratica'' (Clerck, 1757) – Europe to Azerbaijan * ''Nuctenea umbratica nigricans'' (Franganillo, 1909) – Portugal * ''Nuctenea umbratica obscura'' (Franganillo, 1909) – Portugal

References

* Levi, Herbert Walter: ''The orb-weaver genera Araniella und Nuctenea (Araneae: Araneidae).'' in: ''Bulletin of the Museum of Comparative Zoology'', vol. 146, no. 6, Cambridge 1974. ISSN 0027-4100

External links

* Platnick, Norman I. (2008)
The world spider catalog
version 9.0. ''American Museum of Natural History''. {{Taxonbar, from=Q1624740 Araneidae Spiders of Europe Spiders of Asia Fauna of Azerbaijan Spiders described in 1757 Taxa named by Carl Alexander Clerck