Abstract <p><i>Picnochile fallaciosa</i> (Chevrolat in Ann Soc entomol Fr 2:665–668, 1854) is the only known cicindelid to inhabit sub-Antarctic latitudes. Its distribution extends from southernmost tip of continental America to the north of Tierra del Fuego Archipelago (TFA), approximately 1100&#xa0;km north of the Antarctic Peninsula. This site represents a region of great biogeographical importance facing rapid environmental changes due to anthropogenic pressures. Given that tiger beetles are among the most sensitive invertebrates to intensive human activity, generating baseline data on the biology and distribution of <i>P. fallaciosa</i> is crucial to support future research and potential conservation efforts as an indicator to aid decisions of conservation concern. Here, we present a potential distribution map for the species based on known records to identify suitable areas for its occurrence and guide future field surveys. We also provide diagnostic characters of the larva of <i>P. fallaciosa</i>, to facilitate its identification. Our results suggest that suitable habitats for <i>P. fallaciosa</i> have progressively declined and become increasingly fragmented from the Last Glacial Maximum to the present, and this trend is expected to continue through the mid-21st century. Finally, we discuss possible risks to its populations based on impacts documented in other tiger beetle species. Our findings underscore the need for further studies and conservation measures targeting this unique sub-Antarctic species.</p> Implications for insect conservation <p>Our results indicate a progressive reduction and fragmentation of suitable habitats for the rare sub-Antarctic species Picnochile fallaciosa, suggesting an increase in vulnerability to ongoing environmental change. This study highlights the need for further research on Cicindelidae in South America and indicates that larval data and citizen science records may contribute to future monitoring and conservation planning.</p>