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Phylogeny and Evolution of Webspinners (Embioptera)

Introduction
Collaborators
Images

Embioptera (webspinners) rank as one of the most neglected orders of insects. Most people have never heard of them, and even many insect specialists and collectors are relatively unfamiliar with the group. This is unfortunate since they are exceptionally interesting insects. They, along with Hymenoptera, Trichoptera, and Lepidoptera among the insects, are able to spin silk. However, they are the only insects that spin silk as both adults and immatures. Also, they spin silk from glands in their front legs. They use the silk to make galleries in which they live subsocially. Some species appear to exhibit varying degrees of maternal care and nymphs and adults often live in the same galleries.

They occur throughout the world, but are most diverse and abundant in tropical and subtropical regions. Some species live in relatively dry regions and others live in cool cloud forests. Many are arboreal spinning their silk galleries on the surfaces of trees. Others are subterranean and can be found in galleries under rocks. There are a little more than 400 species described, but the number of undescribed species in collections may actually place the species diversity at over 2000. Given that embiids are relatively secretive and few collectors actively attempt to find them, it seems likely that many more species will eventually be discovered once collecting effort approaches that for other taxa.

Kelly B. Miller (Brigham Young University, Provo, UT) works on insect taxonomy, phylogenetics and evolution. He does extensive monographic work revising genera and species groups. He also conducts higher-level phylogenetic work using cladistic analyses of morphological and molecular data to improve classifications and examine evolutionary scenarios. Most of his work has been on Coleoptera, especially the family Dytiscidae, but he has recently developed an interest in embiid phylogeny and taxonomy. In this collaboration he is contributing expertise on insect monography, phylogenetic and systematic theory, and data acquisition and analysis (especially DNA sequence data).

Cheryl Hayashi (University of California, Riverside, CA) works on the evolution and molecular genetics of silk, the protein sequences of different forms of silk and the biomechanical testing of the functional properites of silk. Most of her work has been on spider silks, but she has recently become interested in embiids. To this collaboration she is contributing expertise on molecular genetics and evolution, protein analysis, and evolution, biomechanics and functional analysis of silk.

Janice Edgerley-Rooks (Santa Clara University, Santa Clara, CA) works on embiid behavior and ecology. She currently has colonies of several phylogenetically diverse embiid taxa in culture in her lab where she is able to directly observe various aspects of their life history. She brings to the collaboration expertise in insect behavior and extensive knowledge of embiid silk spinning, colony construction and behavior.

Claudia Szumik (CONICET – Instituto Superior de Entomologia ‘Dr Abraham Willink’, Tucuman, Argentina) works on embiid systematics using morphology. She has examined specimens from most of the major lineages of embiids and coded an extensive number of characters, many of which were previously unknown. She brings to the collaboration considerable knowledge of embiid higher- and lower-level taxonomy and morphology and systematic theory, character coding and analytical methods.

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Silk of Antiplauria urichi on tree bark in Trinidad. The silk galleries form tunnels through which embiids move back and forth from their resting places to their feeding sites at the periphery of the silk. They graze on lichens and algae that grow profusely in the tropical habitat shown here. (Photo: J. Edgerly-Rooks)
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Painting of woodcreeper and Bay-headed tanager at silk of Antipaluria urichi in Trinidad. These birds have been seen tearing into embiid silk in their search for prey. (Painting: E. Rooks)
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Gecko with female embiid (A. urichi). Embiids rarely leave their galleries, but when they do they can encounter predators such as this. Spiders, ants, neuroptera larvae and others are known to catch and kill embiids outside their galleries. (Photo: J. Edgerly-Rooks)
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Antipaluria urichi is attacked by many predators and parasites including this aculeate wasp (Sclerogibbidae). The wasp is ectoparasitic attacking embiid nymphs, paralizing them temporarally and laying an egg on the thorax. The egg hatches and the larva feeds on the nymph from the ouside. Male wasps are winged, but females (like the one pictured here) are wingless. They have strong front legs. (Photo: J. Edgerly-Rooks)
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Most adult female embiids move very quickly when outside the gallery. In this picture can be seen the large front tarsi that are filled with silk glands. Adult females are very similar in form to the nymphs, a characteristic of the order. (Photo: J. Edgerly-Rooks)
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Female Antiplauria urichi spinning silk near egg mass. Silk is excreted from glands in the front legs indicated by the arrow. (Photo: J. Edgerly-Rooks)
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Male and female A. urichi often engage in combat, as shown here. Females will attack especially when guarding an egg mass. Males are winged and are short-lived after maturing. Females live many months with her nymphs. (Photo: J. Edgerly-Rooks)
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Many Australian embiids have wingless males as shown here. These embiids live in leaflitter. (Photo: J. Edgerly-Rooks)
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(Photo: J. Edgerly-Rooks)
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Notoligotoma hardyi silk on lichens on Magnetic Island, Australia. This species is a lichen-specialist. (Photo: J. Edgerly-Rooks)
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