Diversity and compositional turnover of myxomycete communities across Antarctic and subantarctic islands

Myxomycetes remain poorly documented in Antarctic and subantarctic habitats. We documented myxomycetes from King George and Livingston Islands and integrated these new records with reassessed inventories from Macquarie, Campbell, and the Auckland Islands. The dataset comprised 684 collection records representing 78 taxa. The Antarctic surveys yielded 17 taxa associated with moss material, dead Deschampsia antarctica , and penguin dung. Eleven taxa were documented at Elephant Point, substantially expanding the published inventory for Livingston Island, previously represented by a single species record. Recorded richness ranged from nine taxa on King George to 32 on Campbell. Sample coverage ranged from 0.222 to 0.985, identifying King George as a priority for further sampling. Multiple-site Sørensen dissimilarity was 0.845, with turnover accounting for approximately 91.3% of the total. Sixty-one taxa were recorded only in subantarctic inventories, 11 only in Antarctic inventories, and six in both regions. The morphospecies Physarum cinereum was recorded on all five islands. Although heterogeneous sampling limits ecological comparisons, these findings expand Antarctic distributional and substrate records and establish an updated baseline for future surveys across Southern Ocean islands.