Substrate selection and spatial segregation by two congeneric species of Eustala (Araneae: Araneidae) in southeastern Brazil
2015
da Silva Souza, Hebert | Messas, Yuri Fanchini | de Oliveira Gonzaga, Marcelo | Vasconcellos-Neto, João
Habitat and microhabitat selection by spiders are influenced by abiotic and biotic factors, including vegetation structure, natural enemies, and prey availability. Some species are highly dependent on particular conditions, such as the presence of substrates where they remain camouflaged, constantly humid sites or the occurrence of plants bearing glandular trichomes. Others are distributed in areas that include a wide range of physical conditions and interact with several types of prey, predators and competitors. In the present study, we evaluated spatial distribution and substrate selection of two sympatric congeneric species with distinct body shapes and colors, Eustala taquara (Keyserling 1892) and E. sagana (Keyserling 1893), in an area of Atlantic Forest in southeastern Brazil. We focused on the following factors regarding habitat selection: i) distance from the border (forest edge or interior); ii) altitudinal distribution, ranging from 740 to 1294 m; iii) web height above ground level; and iv) plant species used for web attachment. All individuals of both species were located at the forest edge, especially on dry branches. However, they occurred preferentially in different host plants and altitudes. Eustala taquara individuals were strongly associated with Conyza bonariensis, and E. sagana with Hyptis suaveolens and C. sumatrensis. Dry branch preferences might be important to reduce species conspicuousness to visually oriented predators, such as birds and wasps. Spatial segregation between closely related species possibly minimizes interference interactions, such as competition for particular sites or prey items.
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