Saturday 19 November 2016

Leaf mimicking Spiders from China and Southeast Asia.

Mimicry, camouflage that specifically resembles another object such as a plant or another animal in order to escape detection by potential predators or prey, is common in a variety of animals, and particularly common in Insects, with many species documented that resemble leaves, sticks or even bird droppings. Spiders have a similar size range to insects and occupy the same environments. However, while many Spiders exhibit cryptic colouration or behaviour (i.e. colouration or behaviour which enables them to hide or blend into the backgrund successfully) there are few known examples of direct mimickry in Spiders.

In a paper published in the Journal of Arachnology in November 2016, Matjǎz Kuntner of the Evolutionary Zoology Laboratory at the Research Centre of the Slovenian Academy of Sciences and Arts, the National Museum of Natural History, and the College of Life Sciences at Hubei University, Matjǎz Gregorič and Ren-Chung Cheng, also of the Evolutionary Zoology Laboratory at the Research Centre of the Slovenian Academy of Sciences and Arts, and Daiqin Li of the Department of Biological Sciences at the National University of Singapore, descibe leaf mimicry in two species of Orb-weaver Spiders, Araneidae, in the genus Poltys.

Kuntner et al. observed leaf-mimickry in two seperate species of Poltys, one from Xishuangbanna Prefecture in southewestern Yunnan Province and the other in Vietnam. The Vietnam Spider is believed to belong to the species Poltys mouhoti, which was first described in 1862, but which has not previously been identified as a leaf mimic. A DNA barcode for this specimen is made available on the BOLD online database for comparison by other researchers. The Yunnan Spider is thought to be a new species, though it is not yet formally described as such. In addition Kuntner et al. examined online images of a variety of other members of the genus Poltys from Taiwan, Vietnam, Malaysia, Borneo and Hong Kong, from which they conclude that leaf mimicry may be widespread in the genus in Southeast and Eas Asia.

The ultimate leaf masquerade in an orb web spider, an undescribed species of Poltys (Araneidae) from Yunnan. (A)–(C), A female had hung dead leaves from a twig that also included live leaves to masquerade itself from visual predators (A). Upon slight disturbance, she withdrew higher onto the twig (B), (C) where it remained motionless; (D), lateral view of female pose in nature, note her abdomen resembling a dead leaf ventrally and a live, green leaf dorsally, both parts extending into a long and straight, apical abdominal hairy pedicel; (E), female placed on a flat surface, showing her flexible abdominal pedicel, now curved; (F), same, dorsal close up, note ‘‘leaf venation’’ and long hairy pedicel. Kuntner et al. (2016).

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