Richness, diversity and faunal similarity estimators of soil spiders (Arachnida: Araneae) in two vegetation formations of the Cerrado biome

Studies on soil araneofauna in the Cerrado biome are still scarce in northeastern Brazil, especially in Maranhão. This study aimed to conduct an inventory of richness, diversity, and faunal similarity estimators of soil spiders in two vegetation formations of the Cerrado biome, namely gallery forest and Cerrado sensu stricto, in the Inhamum Municipal Environmental Protection Area (EPA), Caxias, Maranhão, Brazil. Collections were carried out during dry and rainy periods using Provid-type traps. For faunal analysis, species richness, diversity and equitability tests were used in the Anafau program and faunal similarity tests in the R program. In the present inventory, 23 families, 37 genera, and 43 species were identified. Richness estimators and species accumulation curves generated for both sites (gallery forest and Cerrado sensu stricto) revealed that the sampling effort was not sufficient to fully quantify soil araneofaunal species; therefore, the richness of soil spiders at the two analyzed sites of the Inhamum EPA is underestimated, suggesting that it might be possible to record even higher richness values in the two studied vegetation formations of the Cerrado biome. The Shannon–Wiener diversity index (H′) and Pielou's evenness index (J′) were similar and indicated a moderate diversity of soil spiders in both gallery forest and Cerrado sensu stricto sites. Similarity dendrogram analysis showed that the soil spider communities analyzed were substantially similar, with most species occurring at both sites.