Minimizing the Wallacean shortfall: a small sample reveals new occurrences of ground-dwelling spiders in native Cerrado and exotic pastures in the Midwestern Brazil

Abstract

Spiders have gained wide acceptance in ecological studies as indicators of environmental quality because they show a strong preference for habitat type and pattern of land use. Knowledge of the spider community in Neotropical landscapes is still incipient. In order to decrease such lack of knowledge, this study provides information on the ground-dwelling spider assemblages in remnants of native Brazilian Cerrado (savanna woodlands) and in exotic pastures (Urochloa spp.; Poaceae). We collected the spiders in two remnants of native vegetation and in four exotic pastures using pitfall traps in Aquidauana, Mato Grosso do Sul, Midwestern Brazil. A total of 141 adults were captured, belonging to 11 families and 22 species of spiders (Arachnida: Araneae). Sixteen species were found in the exotic pastures, 10 in the Brazilian Cerrado, and only four were common to both habitats. We found higher species richness in exotic pastures when compared to Brazilian Cerrado. In addition, four spider species were reported for the first time in the state of Mato Grosso do Sul: Apopyllus silvestrii (Simon, 1905) (Gnaphosidae) sampled in exotic pastures, and Eilica rufithorax (Simon, 1893) (Gnaphosidae), Lycosa inornata Blackwall, 1862 (Lycosidae) and Oxyopes salticus (Hentz, 1845) (Oxyopidae) captured in the remnants of native vegetation. With these results, we minimize the Wallacean shortfall by increasing knowledge on distribution of spiders in remnants of native Cerrado and exotic pastures in the Midwestern Brazil. Moreover, we demonstrate that the ground-dwelling spider assemblage is rich and abundant in exotic pastures, a structurally poor and homogeneous habitat compared to the native vegetation of the Brazilian Cerrado. Then, our findings may aid in understanding the complexity of effects generated by mixed ecosystems on this group of predatory arthropods widely used as bioindicators of environmental and land use changes.