Macroecological invisibility in apple snails (Gastropoda: Ampullariidae): uneven occurrence and molecular coverage...

Apple snails (Ampullariidae) are freshwater gastropods of ecological and economic importance, but their digital representation remains uneven across taxa, regions and data types. Using a 171-species taxonomic reference, we integrated global occurrence and molecular data to assess repository coverage, spatial usability, threshold-based visibility and sampling completeness. The public occurrences comprised 13 349 spatially unique records representing 119 species. Observation-based records accounted for 70.4% of this total and were concentrated in regions where invasive lineages are well documented. Restricting spatial analyses to native-range scientific collections retained only 3614 records for 113 species. Although 154 species were detected in the Global Biodiversity Information Facility (GBIF) species-level records, only 119 had directly spatially usable records; 35 species were GBIF-present, but spatially non-usable, and 17 were not detected in GBIF. Genetic coverage exhibited similar limitations. Public molecular repositories yielded 8730 records across BOLD and GenBank before cross-repository de-duplication, representing 58 species and leaving 113 species without public molecular data. Macroecological visibility declined sharply as minimum occurrence thresholds increased. Sampling completeness remained uneven, with a median of zero in most region-by-resolution combinations, despite apparent improvements at coarser spatial grains. These combined shortfalls systematically leave the principal tropical centres of native diversity analytically under-represented.