Agelenids of the World

Systematics and Taxonomy of Agelenidae, a Worldwide distributed Spider Family

Disturbances in the structure of the prosoma in Tegenaria atrica induced by alternating temperatures (Araneae: Agelenidae)

Publication Type:Journal Article
Year of Publication:2009
Authors:J. Templin, Jacunski, L., Napiorkowska, T.
Journal:Bulletin of the British Arachnological Society
Date Published:2009
ISBN Number:0524-4994
Keywords:/ / ] [Diseases and disorders / / ] [Temperature / Alternating, Abiotic factors, disorders, General morphology, Life cycle and development, Parasites diseases and, Physical factors, Tegenaria atrica (Araneae)., Tegenaria atrica [Prosoma / Prosoma structure anomalies / ] [Development, temperatures / ].

Some unique cases of bicephality in Tegenaria atriea C. L. Koch are described. This phenomenon is known to be the result of broadening and then sagittal bifurcation of the anterior germ band. In consequence there develop two head tagmae. equivalent if the germ band divides symmetrically or non-equivalent if the division is asymmetrical. The bifurcation of the germ band can be shallow. which produces two heads, or deep. which may lead to the development of so-called "Siamese twins". A less frequent cause of bicephality is bifurcation across the anterior end of the germ band in the horizontal plane. Then two head somites develop, the main head, usually with a normal structure. and a so-called accessory head. usually incomplete. situated one above the other. In the authors' opinion the study of the morphology of the anterior body in bicephalous individuals provides exceptional opportunities for studying the inter-relations between the functioning of the particular parts of the brain and widely understood behaviour of spiders.

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