Showing posts with label Orb-weaver Spiders. Show all posts
Showing posts with label Orb-weaver Spiders. Show all posts

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).

See also...

http://sciencythoughts.blogspot.co.uk/2016/10/ceropegia-sandersonii-flower-mimicking.html
http://sciencythoughts.blogspot.co.uk/2016/10/mimetus-lamelliformis-mimetus-wangi-two.html

http://sciencythoughts.blogspot.co.uk/2015/12/baalzebub-mesozoicum-ray-spider-from.html
http://sciencythoughts.blogspot.co.uk/2016/04/maratus-fimbriatus-new-species-of.html
https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi996CGGCXwzOl9LdoisuunFvfvdL09wAkdsPD86ICpVBsjKst1CUHEWTwEDf0iEg62dMfcqeFDJSSADm0KRe5Z0AMOoS77WN1ebSa8XC6lM6gJk59Uxk7xk9OF2s4Dtb9F4i5VnZOHW5M/s200/Stenaelurillus+albus+A+new+species+of+Jumping+Spider+from+the+Western+Ghats+of+India..png
http://sciencythoughts.blogspot.co.uk/2015/04/stenaelurillus-albus-new-species-of.html



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Monday, 26 May 2014

A giant Spider from the Middle Jurassic Daohugou Biota.

In 2011 Paul Seldon of the College of Life Sciences at Capital Normal University in Beijing, the Paleontological Institute and Department of Geology at the University of Kansas and the Natural History Museum in London, along with ChungKun Shih and Dong Ren, also of the College of Life Sciences at Capital Normal University, described a large female Spider, from the Middle Jurassic Daohugou Biota of Inner Mongolia, as a member of the modern Golden Orb-weaver Spider genus Nephila, in a paper in the journal Biology Letters, naming it Nephila jurassica (the Jurassic Golden Orb-weaver Spider).

Finding a modern example of a terrestrial Arthropod species from the Middle Jurassic is, to say the least, somewhat surprising, and in 2013 a team of Scientists led by Matjaž Kuntner of the Institute of Biology of the Scientific Research Centre of the Slovenian Academy of Sciences and Arts, the Department of Entomology at the National Museum of Natural History and the College of Life Sciences at Hubei University published a molecular phylogeny of Orb-weaving Spiders as a whole, in a paper in the journal Molecular Phylogenetics and Evolution which concluded that all living members of the group had a most recent common ancestor more recent than the Middle Jurassic, making the placement of the Daohugou Biota specimen in any modern genus inappropriate.

In a paper published in the journal Naturwissenschaften on 7 December 2013, Seldon, Shih and Ren describe a second giant Spider from the Daohugou Biota, this time a male, which they assign to the same species as the first. They accept Kuntner et al.’s conclusions about the origin of Orb Weaving Spiders, and assign the two specimens to a new genus, Mongolorachne, meaning ‘Mongolian Arachnid’ as Mongolorachne jurassica. 

Mongolorachne jurassica: (a) male  (♂) and female (♀) specimens compared; (b) male part; for explanation see (c). (c) male part, explanatory drawing of (b). Abbreviations: 1, 2, 3, 4, leg numbers; ca, calamistrum; ch, chelicera; cr, cribellar area; cx, coxa; f, fovea; fe, femur; lb, labium; mt, metatarsus; mx, maxilla; op, opisthosoma; pa, patella; Pd, pedipalp; st, sternum; ta, tarsus; ti, tibia; tr, trochanter. Photographs (a) dry, (b) under polarized light with specimen under 70% ethanol; scale bars are 5 mm. Seldon et al. (2013).

Mongolorachne jurassica is placed in a new family, Mongolarachnidae, which are thought to be a stem-group Orb-weaver Spiders, i.e. a members of the lineage which lived before the most recent common ancestor of all modern Orb-weavers, and which may or may not be ancestral to it.

See also…


Armoured Spiders (Tetrablemmidae) are found throughout the tropics, but are at their most diverse and abundant in Southeast Asia. Most species are small, and dwell in leaf litter and soil, including the soil built up around epiphytic plants in the canopies of rainforests. Some cave dwelling species are also known. Armoured Spiders are easy to identify as such since they only have...




Social Spiders are unusual in that the females form colonies of hundreds to thousands of individuals, which cooperate in the...





Jumping Spiders (Salticidae) are specialists who actively hunt their prey, rather than trapping it in webs as most Spiders do. They have extremely well developed vision, with large, forward facing eyes, and an enhanced respiratory system, which enables them to keep their tissues well oxygenated. Jumping Spiders actively move about looking for prey...



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