Community of ground Araneae (Arthropoda, Arachnida) in a seasonally flooded forest in the Northern region of Pantanal of Mato Grosso, Brazil

Abstract

This study aimed to evaluate the community composition of ground dwelling Araneae in a seasonally flooded forest in the Northern region of Pantanal of Mato Grosso, based on its density and emergency activity. Pitfall traps were used to estimate the ground activity and ground photoeclectors to verify the density of emergency throughout the seasonal periods between January 2004 and January 2005. A total of 2,233 spiders were collected, 1,314 with pitfall traps (29 families and 35 genera) and 919 with ground photoeclectors (27 families and 22 genera). Oonopidae (335 ind.: 15,0%), Corinnidae (310 ind.; 13,9%), Gnaphosidae (289 ind.; 12,9%) and Ctenidae (248 ind.; 11,1%) were the main representatives of the community, as well as those with higher density of activity on the soil surface, while Salticidae (177 ind.; 19,3%), Oonopidae (126 ind.; 13,7%) and Gnaphosidae (114 ind.; 12,4%) were those with higher density of emergency. Twelve groups of behavioral guilds were identified, seven were hunting spiders and five were weavers. The analyses concerning temporal variation of the activity and emergence of this community demonstrate that the influence of abiotic factors, such as rainfall and flooding of the forest, are determinant to its structure, influencing the occurrence of groups as Salticidae, Corinnidae and Oonopidae.