Résumé
The silk egg case and orb web of spiders are elaborate structures that are assembled from a number of components. We analysed the structure, the amino acid and fibre compositions, and the tensile properties of the silk fibres of the egg case of Nephila clavata. SEM shows that the outer and inner covers of the egg case consist of thick, medium and thin silk fibres. The silk fibres of the outer cover of the egg case are probably produced by the major and minor ampullate glands. The silk fibres of the inner cover of the egg case from cylindrical glands appears to be distinct from the silk fibres of the major ampullate glands based on their micro-morphology, mole percent amino acid composition and types, and tensile behaviour and properties. Collectively, our investigations show that N. clavata uses silk fibres from relatively few glands in varying combinations to achieve different physical and chemical properties (e.g., color, diameter, morphology and amino acid composition) and functional and mechanical properties in the different layers of the egg case.
Résumé
A technique is proposed for individually marking orb-web spiders aiming at facilitating the identification of the individuals on their webs. To check the efficiency of the method, 17 females and 30 males of Nephila clavipes (Linnaeus 1767) were marked on the dorsal part of the opisthosoma using enamel applied through a disposable syringe. Success was obtained in marking 47 individuals; no death, dispersal or agonistic behavior was observed after the use of the method. This marking did not dissolve in contact with water, resisted the expansion of the opisthosoma and was lost only in the ecdysis. This method also was efficient for males that, being smaller than the females, demand a more careful methodology
Propõe-se uma técnica de marcação individual de aranhas orbitelas visando facilitar a identificação dos indivíduos em suas teias. Para verificar a eficiência do método, 17 fêmeas e 30 machos de Nephila clavipes (Linnaeus, 1767) foram marcados na parte dorsal do abdômen utilizando-se esmalte, aplicado por meio de seringa descartável. Obteve-se sucesso na marcação dos 47 indivíduos, não sendo observada morte, dispersão ou comportamentos agonísticos após o uso do método. Esta marcação não dissolveu em contato com a água, resistiu ao aumento do opistossoma e foi perdida somente na ecdise. Esse método também foi eficiente para os machos que, por serem menores que as fêmeas, exigem uma metodologia mais cuidadosa.
Sujets)
Animaux , Mâle , Femelle , Différenciation sexuelle , Araignées , MéthodesRésumé
An ephydrid, Hyadina porteri Brèthes, 1919, is found to be a senior synonym of Hippelates australis Sabrosky, 1955. New combination: Liohippelates porteri (Brèthes). Two new species, Pseudogaurax souzalopesi from Peru and P. silbergliedi from Panama are described and placed in the synopsis by Sabrosky (1966).