Exploration of the Potential Suitable Distribution Range of the Lyophyllum decastes Complex in High-Altitude Cold Regions of Southwest China

Climate change may alter the abiotic conditions associated with macrofungal occurrence, but projections for taxonomically unresolved species complexes require cautious interpretation. Here, we used an AICc-optimized MaxEnt model to characterize the climate-defined aggregate suitability envelope of records assigned to the Lyophyllum decastes (Fr.) Singer complex in Sichuan, Yunnan, and Xizang, Southwest China, under current conditions and four RCP scenarios for the 2050s and 2070s. After spatial thinning, 70 occurrence records compiled from field surveys and published sources were modeled with correlation-filtered bioclimatic variables. The optimized model showed high discrimination for the pooled occurrence dataset (mean AUC > 0.95), and mean temperature of the coldest quarter had the largest contribution (50.8%). Projected changes differed between scenarios, with increasing fragmentation and reductions in highly suitable climate space under several futures. These outputs do not represent a lineage-resolved species distribution, as the occurrence records were not uniformly verified by molecular barcodes, and the model omits host availability, vegetation, soil, land use, dispersal, and other biotic processes. We therefore interpret the maps as a hypothesis-generating, aggregate climatic envelope for the complex that can guide stratified field surveys, molecular sampling, and habitat monitoring rather than as direct evidence of taxon-specific physiological tolerances or realized distributions.