A checklist of diatoms with four endemic records and phytogeographical distribution from water habitats of Iran

This paper presents the first comprehensive checklist of diatoms in Iran, spanning the period from 1842 to 2024. The checklist encompasses 1,073 diatom species, representing 3 phyla, 61 families, 163 genera, and several infraspecific taxa and four endemic species. Records derive from a diverse range of habitats including freshwater, brackish, marine, and saline environments across Iran. Bacillariophyceae show the highest frequency among the diatom taxa, accounting for 87% of the species with 36 families, 119 genera, and 932 species. Mediophyceae ranked second with 8% of the records, represented by 13 families, 25 genera, and 87 species. Coscinodiscophyceae accounted for 5% of the diatom taxa, comprising 12 families, 19 genera, and 54 species. Bacillariaceae were the most diverse family, with 162 species. Furthermore, 17 families were represented by a single genus and species. Phytogeographically, the dominant species were observed in the Hyrcanian and freshwater regions. The highest similarity (87%) was found between the Irano-Torrany and Hyrcanian areas in terms of shared species.