Aranhas (arachnida, araneae) das matas metropolitanas de Belém: inventário estruturado na área de pesquisas ecológicas do rio Guamá

Abstract

Spiders are animals belonging to the order Araneae of the arachnid class. There are currently 40024 species described in 3681 genera worldwide. The production of inventories of arachnofauna in Brazil, especially in the Amazon, are still very scarce. However, these studies can generate subsidies for the conservation of species and ecosystems, as well as being fundamental for the long-term understanding of the environmental impacts of urbanization on tropical forests. The objective of this study was to promote a structured inventory of the spider fauna in the Guamá River Ecological Research Area, comparing patterns of incidence/abundance with another studied area around the city of Belém (Mata do Hospital Bettina, Campus UFPA, Guamál. Collections were made in a terra firme area in December 2007 and January and May 2008. Three collection techniques were used to obtain the samples: entomological umbrella, used for capturing arboreal animals (38 samples); fall traps, for capturing burrowing animals (100 samples); and Winckler extractors used for sampling small animals from the litter (45 samples). The samples resulted in a total of 1590 individuals, 630 adults and 960 juveniles, distributed in 30 farmlands, with Araneidae (374 individuals), Salticidae (368 individuals), Theridiidae (213 individuals) and Oonopidae (111 individuals) being the most abundant families, representing about 70% of the total spiders collected. More than 60% of the collected specimens are juveniles. Araneidae (143 individuals), Salticidae (113 individuals) and Theridiidae (101 individuals) had the highest number of adult representatives, while Ctenidae, Dipluridae, Gnaphosidae and Sparassidae had only juvenile representatives. Clubionidae, Nesticidae and Senoculidae were the families that presented only adult individuals. Entomological umbrella samples accounted for more than 75% of the specimens collected. So far, individuals have been identified only to family level. However, the results obtained show that other inventories carried out in the Amazon also presented the families Araneidae, Salticidae and Theridiidae as the most abundant. At the end of the specific identification of the araneofauna, an incidence/abundance matrix will be constructed and used in the diversity analyses.