Sep. 25, 2013 — A recent paper published in the open access journal Zookeys provides a first-time glimpse in the natural history of the enigmatic spider species Progradungula otwayensis. Lurking in the hollows of old myrtle beech trees and thus hard to collect, this extraordinary spider is an endemic species confined strictly to the beautiful Great Otway National Park (Victoria, Australia).
P. otwayensis belongs to the small spider family Gradungulidae which consists of seven genera with a total of 16 described species found exclusively in eastern Australia and New Zealand. The genus Progradungula to which the species studied here belongs is among the few cribellate ones in the family. This term refers to the cribellum, a web producing organ which, unlike normal spinnerets, produces extremely fine fibers which are combed out by the calamistrum, producing silk with a wooly texture. The fibers are so small in diameter that prey insects easily become entangled in them, without any glue needed.
To add to its mystery P. otwayensis weaves highly stereotyped ladder-shaped webs, where they stand facing down after sunset, waiting for preys which will be caught by using the ladder as a trap -- a behavior which was already described in detail by now retired arachnologist Mike Gray (Australian Museum) for the only known other species of this genus, P. carraensis. A single thick and shiny silk thread is then used by the spiders to provide a zip-line like connection between the external webs and the security of the enigmatic retreat in the hollows of ancient myrtle beech and mountain ash tree.
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