Biotic rather than abiotic factors influence ground-dwelling mygalomorph spider assemblages along an altitudinal gradient in the Brazilian semi-arid domain

Abstract

The species richness of organisms associated with altitudinal gradients tends to decline with increasing altitude, however, this pattern is not observed in mygalomorph. The present study tests the hypothesis that the richness and abundance of ground-dwelling mygalomorph spiders will be positively correlated with the increase in altitude, as well as will be influenced by variation of potential prey along an altitudinal gradient in the Brazilian semi-arid domain. Sampling took place during August 2020 to August 2021, through pitfall traps, totaling 50 traps/area/month. A total of 125 adult individuals belonging to 10 morphospecies were collected along the altitudinal gradient. Theraphosidae was the richest family in morphospecies, the most abundant mygalomorph was Neodiplotele caucaia Gonzalez-Filho, Lucas & Brescovit, 2015, Guyruita sp., and Diplura sanguinea (F.O. Pickard-Cambridge, 1896). Our results shows that mygalomorph abundance and species richness were affected by potential prey availability and not by altitude per se. Therefore, our results shows that the biotic (e.g., availability of potential preys) and no abiotic (e.g., elevation) may have a key factor to the mygalomorph spider assemblage modulation along an altitudinal gradient. The study opens precedents for further investigations on the distribution patterns of mygalomorph spiders in the Brazilian semiarid region.