Subterranean Invertebrate Fauna in Iron Formations From Southeastern Brazil: A Comparison Between Caves and Mesovoid Shallow Substratum

ABSTRACT Aim We aimed to understand the ecological connections between caves and mesovoid shallow substratum (MSS) in Iron Formations from southeastern Brazil. Location Iron Quadrangle and Southern Espinhaço Range, southeastern Brazil. Taxon Subterranean invertebrates. Methods Our dataset compiles species distribution data of subterranean invertebrates from long‐term monitoring projects conducted in three localities: Brumadinho, Itabirito, and Conceição do Mato Dentro. Sampling occurred from April 2007 to December 2023 using active search methods in caves and MSS traps in iron‐duricrust (canga) formations. We used multivariate analyses to compare the invertebrate composition between caves and MSS. We also assessed the effect of geographic distance between them on total β‐diversity, species replacement, and richness differences. Results We recorded 97,967 individuals and 1588 invertebrate morphospecies: 11,738 individuals and 994 morphospecies in caves, and 86,229 individuals and 945 morphospecies in MSS. Six phyla were sampled, with Arthropoda comprising 98% of all organisms. In total, 351 invertebrate morphospecies (22.1%) were shared between caves and MSS, with 643 (40.5%) sampled only in caves and 594 (37.4%) restricted to MSS. Only four subterranean‐specialised invertebrates were shared between caves and MSS. Species composition differed more between subterranean environments than between localities, with β‐diversity analyses revealing high species replacement as the primary driver. Geographic distance played a negligible role in compositional differences (Sorensen dissimilarity) between caves and MSS, with β‐diversity always above 83% regardless of the distance between these environments. Main Conclusions Caves and MSS in Iron Formations support distinct subterranean invertebrate communities, with more species restricted to each environment than shared, regardless of the geographic distance or structural connectivity between them. These findings highlight the ecological relevance of both environments and their role in sustaining biodiversity within Iron Formation systems. Consequently, conserving both environments is needed to protect the full extent of subterranean biodiversity in these unique ecosystems.