Spider species richness and sampling effort at Cracraft´S Belém Area of Endemism.

Alexandre B Bonaldo,Ubirajara De Oliveira,Manoel B Aguiar-Neto,Bruno V.B Rodrigues,Adalberto J Santos,Marlúcia B Martíns,Antonio D Brescovit

doi:10.1590/0001-3765201720150378

Abstract

A list of spider species is presented for the Belém Area of Endemism, the most threatened region in the Amazon Basin, comprising portions of eastern State of Pará and western State of Maranhão, Brazil. The data are based both on records from the taxonomic and biodiversity survey literature and on scientific collection databases. A total of 319 identified species were recorded, with 318 occurring in Pará and only 22 in Maranhão. About 80% of species are recorded at the vicinities of the city of Belém, indicating that sampling effort have been strongly biased. To identify potentially high-diversity areas, discounting the effect of variations in sampling effort, the residues of a linear regression between the number of records and number of species mapped in each 0.25°grid cells were analyzed. One grid, representing the Alto Turiaçu Indigenous land, had the highest deviation from the expected from the linear regression, indicating high expected species richness. Several other grid cells showed intermediate values of the regression residuals, indicating species richness moderately above to the expected from the model.

Highlights

Spiders are both highly abundant and diverse organisms
Portions of the Amazon Basin remain undersampled and the checklists provided were mostly based in the recognition of morphospecies, a situation that severely limits the study of biogeographic patterns
Studies on biogeography of vertebrates (Haffer 1978 [birds], Ávila-Pires 1995 [lizards], Silva and Oren 1996 [primates], Ron 2000 [amphibians]) indicated that the distribution of several species in the Amazon Basin is not continuous and proposed that the similar patterns of limited distribution of these vertebrates could lead to the recognition of areas of endemism

Summary

Introduction

Spiders are both highly abundant and diverse organisms. There are above 46.000 species described (World Spider Catalog 2017), but these figure is presumed to represent only a fraction of the actual species diversity of the group (Costello et al 2012). The list represents only a portion of the sampling at hand, and is obviously just a fraction of the actual spider species richness in the area.

Results

Conclusion