Recorded and predicted occurrence of slime moulds (Eumycetozoa) in Poland from Central and Eastern European data.

Aim: To quantify recorded and potential (model-based) occurrence of slime moulds (Eumycetozoa) in Poland within a harmonised Central and Eastern European (CEE) framework, and to provide a reproducible basis for targeted survey planning and biodiversity assessment. Location: Poland, with a comparative regional context based on harmonised occurrence data from 16 countries in Central and Eastern Europe. Methods: We used a taxonomically standardised, georeferenced Darwin Core dataset of Eumycetozoa compiled for 16 CEE countries. A Polish national checklist was assembled and annotated with habitat, substrate and national bibliographic information. We delineated an additional set of candidate taxa from the wider CEE pool and, where data permitted, evaluated them using presence-only species distribution models to estimate broad-scale climatic suitability in Poland and to identify regions and taxonomic groups concentrating potential diversity. Results: The Polish checklist comprised 278 species in six orders, strongly dominated by Physarales, Trichiales, Stemonitidales and Cribrariales, with known records spatially clustered in a limited set of well-surveyed regions. Comparison with the regional pool indicated 365 additional candidate taxa in 11 orders not yet recorded from Poland. Of these, 101 species could be modelled, and 31 achieved medium or high model-based suitability within Poland. Adding these 31 taxa to the recorded checklist yields a conservative estimate of 309 species likely to occur nationally, whereas including all candidates provides a theoretical regional maximum of 643 taxa. Model predictions highlighted western and northern voivodeships as concentrating suitable climatic conditions for multiple candidate species. Conclusions: Harmonised occurrence data, an annotated national checklist and model-based predictions together indicate substantial survey gaps and a considerable pool of likely yet unrecorded taxa in Poland. These outputs provide a transparent, reproducible framework to prioritise future fieldwork, fill spatial and taxonomic gaps, and support the development of slime moulds as biodiversity indicators for forests in Poland, with regional climatic priorities to be validated against forest type, substrate availability and survey-time weather.