The 22 publications contained in this volume, with authors from around the world, honor the life and work of Andrzej Witkowski. Subjects this issue include many of the typics Andrzej himself covered in his work on diatoms, with an emphasis on taxonomy (14 of the papers), but also biogeography, ecology, biology and products. Some of the works help resolve taxonomic problems (e. g. Mann & Trabajo, Williams et al.) while others introduce taxa new to science, including new genera (e. g. Mayama et al., Garcia) and species (e. g. Van de Vijver & Pottiez, Rybak et al. among many others) with many of them being named for the honoree. Insights into valve ultrastructure (e. g. Lobban, Kociolek et al.) are also provided. Beyond these subjects related to morphology, taxonomy and systematics, we also find work on the Baltic Sea (Virta & Teittinen) and diatoms from the South Atlantic (Klimova et al.). Works on diatom distributions (Riaux-Gobin et al.) auxospore formation (Kaczmarska et al.), paleontology (Naya, Hartung et al.) and remediation via diatom products (Roychoudhury et al.) are also offered.

The works in this volume honor a leader in diatom sciences, whose interests were as far ranging and his travels in pursuit of knowledge on diatoms. An enthusiastic researcher, generous and supportive teacher, and person full of life and words of support, this memorial volume well suits his love of life and science.