Ditmar was originally trained as an electrical/chemical engineer and spent over 30 years as a Scanning Electron Microscope operator in Germany. Although he claimed he was an amateur, Ditmar was an accomplished, self-taught diatomist. He developed a strong collaboration with Horst Lange-Bertalot and described 25 diatom genera and somewhere in the realm of 1000 species (as author or co-author). Besides diatoms, Ditmar's other great love was travel. He combined his interest in diatoms and biodiversity of the earth. Ditmar visited over 70 countries around the world, many for multiple times, and many to discover the endemism and diversity of diatoms and terrestrial plants.