Nematoda & Crustacea taxonomist. Described 8 families, 61 genera & 239 species of nematodes.
His private collection deposited after his death at University of Amsterdam.
Bibliography: Karssen (2006) Life and work of Dr. Johannes Govertus de Man (1850-1930), A Crustacea and Nematoda specialist. Brill, Leiden, The Netherlands.
Phytopathologist & 1st director Plant Protection Service, The Netherlands. Taxonomy of plant-parasitic nematodes: description of Aphelenchoides fragariae.
Parasitologist at Utrecht University. Founder (in 1956) of the journal Nematologica. Co-author of the book “Manual of Agricultural Helminthology” Taxonomy of free-living marine and animal parasitic nematodes.
Started in 1950 with a permanent slide collection at the Plant Protection Service. Deposited in 1953 the first type slides (Paratylenchus goodeyi) in this collection. Moved in 1958 to Wageningen University.
In 1955 appointed as nematode taxonomist at the Plant Protection Service. Moved in 1958, with the slide collection, to Wageningen University. First curator of the Nematode Collection of Wageningen University (NCWU). Developed a unique nomenclatorial card system. Described 180 new nematode taxa, published 185 papers on nematode taxonomy. Retired in 1988.
Nematologist and taxonomist at Wageningen University. Second curator of the Nematode Collection of Wageningen University (NCWU). Developed the Maturity Index. Retired in 2007.