Although harvestmen are a significant group of terrestrial invertebrates, their effective protection has not been ensured in Slovakia to this day. Not a single species belonging to the order Opiliones has been included in the “Red Data Book of threatened and rare plant and animal species of the Czech and Slovak Federal Republic”. Harvestmen have also not been included in the Red List of plants and animals of Slovakia. Since a new Red Data Book of invertebrates of Slovakia is currently under production, a checklist and the first Red List of harvestmen of Slovakia were prepared. Thirty-five species of harvestmen were identified based on the analysis of all records published since 1873 and our unpublished records. A total of 5,254 records of harvestman species from 2,772 locations were analysed across 318 grid cells, each measuring 10 × 10 km. Two species were recorded exclusively in the Pannonian and six in the Alpine biogeographical region, while the remaining species occurred in both regions. All 35 species were assessed based on the current IUCN Red List criteria, categorising them as follows: Critically Endangered (Holoscotolemon jaqueti), Endangered (Siro carpaticus), Vulnerable (Gyas titanus, Ischyropsalis manicata, Paranemastoma kochii, Paranemastoma quadripunctatum), Near Threatened (Lacinius dentiger, Lacinius horridus, Opilio parietinus, Platybunus pallidus), Least Concern (22 species), Data Deficient (2), and Not Evaluated (1). A brief overview of the history of Opiliones research in Slovakia is also provided.
