The Elusive Troglobius brasiliensis (Collembola: Paronellidae), a Critically Endangered Species Rediscovered and Redescribed in Its Habitat and Food Web.

Troglobius brasiliensis is a troglomorphic species known only from a single cave in the Brazilian rain forest. This is the first record of the species since its original collection in 1988 and subsequent formal description approximately 30 years ago. We present an integrative redescription of T. brasiliensis based on detailed morphological analysis with scanning electron microscopy. It is a coded redescription with a molecular marker (COI), comprehensive notes on its habitat. The species was found exclusively along the riverbank, restricted to a single sector of the aphotic zone, approximately 40 m from the main cave entrance; both adults and juveniles were observed, indicating a functional and reproductive population. The detailed morphological documentation presented here allows robust comparisons with all known species of Troglobius, and other members of family Paronellidae, contributing to refining species diagnosis and providing a standardized framework for future taxonomic and conservation studies involving subterranean fauna.