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Plebs cyphoxis Simon, 1908 Western Bush Orb Weaver

This spider is common in southwest Western Australia into South Australia. The female is medium sized and has the typical 'Plebs' pattern on the underneath of the abdomen, being a dark area surrounded by a white or cream squarish U shape, the opening of the U towards the rear and ending before the spinnerets. Beside or a little towards the anterior side of the spinnerets are two large white to cream blobs. The pattern is sometimes absent in males. These spiders build orb-webs in grass and low vegetation. The web often has a vertical stabilimentum, or web decoration, like clock hands set at 6 o'clock. This species is very similar to Plebs eburnus from the east coast of Australia, and like the eastern spider stays in its web in the daytime. It appears to have more obvious and pointier shoulders than P. eburnus, whose stabilimentum is usually set at 5 past 7 (or 5 to 5) on the clock. In female P. cyphoxis, the base of the scape is heavily convoluted. In P. eburnus it is straight without curves. In males, there are differences in the median apophysis of the palpal organ. Both species seem to overlap in South Australia. The specific name comes from Hippocrates' use of the term cyphoxis, Greek for hump, to describe excessive curvature of the thoracic spine, as in a mid back hump. In this case it may refer to the prominent shoulder humps. Thanks to Dr Volker Framenau for his help with this species. ♀ 9 mm ♂ 6mm

Female adult in web, from above the spider


The web is nearly vertical so this photo is taken from beside the centre of the web, looking horizontally.

Araneus cyphoxis
Photo: Ed Nieuwenhuys

Female adult showing stabilimentum


Araneus cyphoxis
Photo: Ed Nieuwenhuys

Female adult in web, Western Australia


Araneus cyphoxis
Photo: Wendy Eiby

 

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