Spider webs as reservoirs of culturable fungal diversity: evidence from orb-weaving Cyclosa mulmeinensis spider in Thai rice agroecosystems

Spider webs are increasingly recognized as passive environmental collectors; however, fungi remain among the least explored biological components associated with spider silk, particularly when examined using culture-based and taxonomically resolved approaches. In this study, we investigated the culturable fungal diversity associated with two-dimensional, debris-decorated orb webs—both with and without egg sacs—constructed by the orb-weaving spider Cyclosa mulmeinensis in rice agroecosystems in Thailand. Using a standardized field-to-laboratory isolation workflow combined with genus-appropriate multilocus phylogenetic analyses, decorated orb webs were sampled from three provinces, and fungi were isolated via dilution plating on potato dextrose agar supplemented with chloramphenicol. A total of 112 fungal isolates were recovered, grouped into 45 colony morphotypes and resolved into 23 taxa across six genera: Alternaria , Aspergillus , Cladosporium , Fusarium , Penicillium , and Talaromyces . Taxonomic placement was inferred primarily from multilocus phylogenetic analyses, with morphological characteristics used as supporting evidence. Several isolates formed well-supported lineages within Cladosporium and Talaromyces that could not be assigned to any described species, indicating the presence of potentially undescribed taxa. Fungal richness and taxonomic composition varied among sampling locations, and exploratory comparisons suggested that debris-decorated webs bearing egg sacs harbored a higher culturable fungal diversity than debris-decorated webs without egg sacs. Collectively, these findings highlight spider webs as a low-impact, non-destructive substrate for accessing viable fungal biodiversity in rice agroecosystems, facilitating repeatable culture-based recovery of taxonomically informative—and potentially novel—fungal lineages for biodiversity assessment and environmental monitoring.