Father Chrysanthus

Wilhelmus Egbertus Antonius Janssen (1 September 1905 – 4 May 1972), better known as Father Chrysanthus (Also known as Pater Chrysanthus.) called it "excellent" in 1977. The first edition of Chrysanthus's ("Dutch Spiders"), written for the 's series, was published in 1954. Additional editions were published in 1963, 1971, and 1980. The Dutch entomologist favorably reviewed all four editions.

In 1957, Chrysanthus became interested in the spiders of New Guinea after Brother Monulf sent him a collection of spiders he amassed during missionary work in Merauke and Mindiptana in Western New Guinea; Chrysanthus had previously met Monulf in Wellerlooi in 1953. As Chrysanthus became known for his work on New Guinea spiders, museums were interested in providing him with specimens as they lacked specialists in this area. the biologist , and the zoologist Michael H. Robinson. In 1982, Robinson wrote "almost all of the recent work on the taxonomy of New Guinea spiders" was due to Chrysanthus, and that after his death there was no one who knew as much about the taxonomy New Guinea spiders. Valerie Todd Davies, in a 1997 book review, wrote that it "is regretted" that the authors of a book on spiders of Southeastern Asia did not cite Chrysanthus's papers on New Guinea spiders.

Within taxonomy, he helped show that Metellina mengei and Metellina segmentata were in fact distinct species and not merely varieties of one species; G. H. Locket and A. F. Millidge, who had previously considered them to be the same species, listed them as distinct species in the third volume of British Spiders because of the analysis in Chrysanthus's paper. Chrysanthus is also known for work in the genus Coelotes. this was published in a 1965 paper in . This led him to write a proposal in The Bulletin of Zoological Nomenclature as an amendment to Herbert W. Levi and Otto Kraus's proposal concerning Coelotes. In 1979, the International Commission on Zoological Nomenclature accepted Chrysanthus's version of the proposal.

In 1955, Chrysanthus joined the editorial board of the journal — a position he would hold until 1971. He was also a visiting researcher at the Naturmuseum Senckenberg. He was a member of the Netherlands Entomological Society, In 1967, he was given the position of Scientific Collaborator at the Rijksmuseum van Natuurlijke Historie. Over the course of his lifetime, he wrote over one hundred papers.

Death and legacy Chrysanthus died on 4 May 1972, at the age of 66, G. H. Locket named the species Nasoona chrysanthusi "in affectionate memory of the late Father Chrysanthus and in admiration of his work on New Guinea spiders" in 1982.