Taxonomic Revision and Field Identification Key of Pyrocystis and Dissodinium (Dinophyceae) Species from Chinese Coastal Waters

The marine dinoflagellate genera Pyrocystis and Dissodinium are core components of coastal phytoplankton and bioindicators for eutrophication monitoring, yet long-standing taxonomic confusion, misapplied Latin epithets, and inconsistent morphological records widely exist in domestic marine surveys across China’s seas. In this study, we collected cyst specimens from China’s seas and systematically reviewed domestic phytoplankton literature published from 1985 to 2025, alongside authoritative taxonomic databases AlgaeBase and WoRMS, to revise historical misclassification records of the two genera. We clarified a total of 12 valid species distributed in Chinese waters, catalogued prevalent nomenclatural errors in previous surveys, and constructed a standardized morphological identification key supplemented with field rapid recognition tips tailored for frontline harmful algal bloom monitoring. Our results resolved decades-long synonym and generic assignment confusion for regional monitoring staff, unified domestic morphological discrimination criteria, and reduced artificial identification bias. This taxonomic revision improves the consistency and comparability of multi-year coastal phytoplankton monitoring data and provides a practical morphological toolkit for routine marine ecological assessment.