van De Vijver, B., Coomans, A. and Pottiez, M. 2025. Planothidium islandicum sp. nov., a new cavum-bearing Planothidium species from the Westfjords, northwestern Iceland (Achnanthaceae, Bacillariophyceae). Phytotaxa. 731, 2 (Nov. 2025), 183–186. DOI:https://doi.org/10.11646/phytotaxa.731.2.9.