The Arachnological Collection (Chelicerata, Arachnida) at the Federal University of Bahia, Brazil: taxonomic status, temporal patterns, geographic coverage and data availability

Brazil hosts more than 300 zoological scientific collections, although these are unevenly distributed, with over 60% concentrated in the Southeast and South regions. The challenges associated with this imbalance, as well as limited access to their data, can be mitigated through open-access initiatives. Nevertheless, of the 24 arachnological collections registered on brazilian virtual platforms such as SpLink and SiBBr, 29% still lack publicly available data. This study aims to present an analytical overview of the Arachnid Collection of the Natural History Museum of Bahia-ARAC/MHNBA, currently the only collection in the Northeast region with openly accessible data. With nearly 50 years of history, the collection comprises approximately 15,000 cataloged specimens, available on SpLink since 2016. Data were compiled from Heritage Books and the platform itself. The ARAC/MHNBA collection is organized into nine subcollections: Araneae, Scorpiones, Opiliones, Amblypygi, Pseudoscorpiones, Thelyphonida, Solifugae, Parasitiformes and Acariformes. Most specimens were cataloged during the 2020s and over 60% are identified to species level, with spiders and scorpions showing the highest taxonomic resolution. The collection includes material from all brazilian regions - the vast majority of the Northeast, including the state of Bahia - as well as 22 specimens from three other countries. As a university-based collection, its development is closely tied to student training and research projects, operating without formal institutional support. This study highlights the importance of institutionalizing university collections in Brazil and emphasizes the role of regional collections and open data in democratizing biodiversity knowledge.