Curation of Gastrotricha species deposited in Museum of Biological Diversity (MDBio, Brazil): overview and updates

Biological collections are indispensable repositories of primary biodiversity data and provide the empirical basis for taxonomic, systematic, ecological and biogeographical research. By preserving voucher specimens and associated metadata, they ensure the reproducibility and reliability of biodiversity research. The collections of the Museum of Biological Diversity (MDBio) at the State University of Campinas play a pivotal role in documenting and safeguarding meiofaunal diversity in Brazil. Here, we present a critical curatorial assessment of the Gastrotricha collection deposited in MDBio, encompassing photographic records, microscope slides, and scanning electron microscopy (SEM) stubs. The collection currently contains specimens representing 63 described species, including the holotypes of 25 species, making it the principal reference collection for Gastrotricha in Brazil. An additional 11 taxa are represented by specimens assigned only to genus level or treated under open nomenclature (aff. or cf.), whereas eight specimens remain unidentified. A comprehensive curatorial audit reconciled museum records with the published literature, correcting accession numbers, taxonomic identifications, geographic information, and type-series documentation, thereby substantially improving the scientific reliability and long-term value of the collection. Owing to the richness and uniqueness of its holdings, MDBio has emerged as the principal reference collection for Gastrotricha in Brazil and a significant repositories of the phylum worldwide, making a substantial contribution to the documentation and long-term preservation of one of the most neglected components of metazoan biodiversity. Beyond documenting the holdings of a major reference collection, this study demonstrates how continuous curatorial revision enhances the scientific reliability, reproducibility and long-term value of museum collections, particularly for microscopic soft-bodied taxa whose taxonomic interpretation changes rapidly over time.