Biodiversity under rocks: the role of microhabitats in structuring invertebrate communities in Brazilian outcrops

There is little knowledge on the factors that can structure communities of tropical arthropods that live under rocks (lapidicolous communities). Using 28 rock shelters in a small granitic outcrop, we examined the relations am ong area, inclination, organic matter content, substrate moisture and dista nce from the border of the outcrop and richness and diversity of the commun ities. In total, we collected 1216 individuals from 106 morphospecies of Ar aneida, Acarina, Polyxenida, Spirostreptida, Dermaptera, Neuroptera, Orthop tera, Dictyoptera, Psocoptera, Coleoptera, Hymenoptera, Diptera, Embioptera , Homoptera, Isoptera, Heteroptera, Lepidoptera, Collembola, Nematoda and O ligochaeta. The richness and diversity of the lapidicolous communities were significantly correlated with area, inclination and distance from the edge of the outcrop in the dry season. The richness and diversity of lapidicolo us communities were significantly correlated with organic matter, substrate moisture and area in the rainy season. Space availability seemed to be an important structuring factor for lapidicolous communities in the present st udy, the most significant variables (substrate moisture and organic matter) were related to shelter area.