Juan Heyns passed away in Pretoria, due to a pulmonary infection after heart surgery. He had struggled for weeks against the disease, but finally lost the unequal battle.
He was born in Humansdorp, a small town along the famous Garden Route in South Africa’s Cape Province. There he spent his youth until he went to Stellenbosch to study at the University. Here he met Errie, whom he married in 1952. After obtaining a B.Sc. degree in Agriculture in 1953, he started his carreer as an assistant professional officer at the Tobacco Research Institute in Rustenburg, Transvaal, amidst a rich farming area producing several tropical and sub-tropical crops and fruits, and Virginia tobacco. He became responsible for research on insect and nematode pests on tobacco.
Some years later he was seconded to the University of Pretoria to study for an M.Sc. degree in Entomology. Immediately after obtaining this degree in 1959, he was seconded to the University of Wisconsin, USA, to study nematology under Gerald Thorne. This resulted in a Ph.D. degree 2 years later for a thesis entitled ‘Taxonomic studies on nematodes from South Africa’.
After returning to South Africa, he became Head of the Nematology Section and later of the Economic Zoology Section of the Plant Protection Research Institute (PPRI) in Pretoria. In January 1971, Juan Heyns was appointed senior lecturer in the Department of Zoology of the Rand Afrikaans University (RAU) in Johannesburg. Only 1 year later he was promoted to full professor in charge of courses on invertebrate zoology, ecology and philosophy of science for undergraduate students, and nematology for post-graduate students.
He became a member of several scientific committees, Chairman of the Department of Zoology (1978-1980) and Chairman of the Subfaculty of Biological Sciences (1974-1976 and 1983-1987) . He supervised 25 M.Sc. and 11 Ph.D. students. Many of his former students became leading nematologists in South Africa. After his official retirement in 1989, he continued, first full-time, later part-time, his research at the same department until 1994. After that, he still carried on with his research, having his microscope and literature with him at home, remaining active to the end, with four papers still in press.
In 1995, the University of Stellenbosch awarded Juan Heyns a D.Sc. degree on a thesis summarising his published scientific work on plant and soil nematodes. His early investigations were of a more applied nature, directed towards ad hoc problems encountered by the tobacco growers in Transvaal. His real interest, however, was always in taxonomy and his Ph.D. work under Gerald Thorne was the real start of a lifetime endeavour to contribute to the taxonomy of primarily southern African plant, soil and freshwater nematodes, but also of many species from other parts of the world.
Numerous surveys and collection trips allowed him to establish a large reference collection at PPRI, which was later on continued by some of his former students. It would become one of the largest and best-kept nematode collections in the world, with more than 22 000 permanent slides.
After his appointment at the RAU, Juan Heyns mainly focused on dorylaims, especially Longidoridae, leaving tylenchs to the nematologists at PPRI (Dr E. van den Berg and collaborators). Later on he became interested in freshwater nematodes and started a collection of them at the RAU. Apart from his personal research in taxonomy, he guided most of his students in that direction. It was his strong conviction that taxonomy was the essential basis for other biological research.
His descriptions of 325 new species, 28 new genera, two new families and a large number of redescriptions, published in more than 220 papers, were detailed, accurate and beautifully illustrated. He was, however, not satisfied with mere α-taxonomy, and included as much information as possible on intraspecific variation, relationships, geographical distribution and ecology of the species described. Furthermore several monographic studies of genera or higher categories were published, e.g., on Dorylaimellus (1963), Aporcelaimidae (1965), Nygolaimidae (1968), Acrobeles and related genera (1968, 1969, 1970), South African Criconematidae (1969, 1970, 1971), Actinolaimidae (1970), Chronogaster (1980, 1984) and southern African Longidoridae (since 1965).
When he started with taxonomy, the only nematodes that had been studied in South Africa were a few Meloidogyne species. Due to his efforts and those of his students and coworkers, nearly all plant-parasitic and the vast majority of free-living genera commonly encountered in terrestrial and aquatic habitats of South Africa can be safely identified and more than 700 species have been recorded. The high standard of his work served as an example for many nematologists world-wide.
In the 1980s Juan Heyns started, with some of his collaborators, to expand his work on longidorids to electron microscopy studies, TEM as well as SEM. In the same period he became more engaged in international collaborative studies. He received several research grants and invitations to co-operate in joint projects. He was also frequently invited to participate in symposia as introductory speaker, discussion leader of colloquia or as chairman of sessions.
In 1996 he was elected as Fellow of ESN and in 1997 as Honorary Member of the Nematological Society of southern Africa.
Apart from nematodes, Juan Heyns was passionate about birds. He was an expert on South African birds, but had also a great knowledge about European and American birds. Whatever country he visited, his binoculars and guide books were always within reach. During these visits he made from time to time drawings and water-colours of landscapes or of typical villages, revealing genuine artistic qualities.
His many-sidedness is also demonstrated by his sporting activities. For many years he was not only a daily jogger, but also a marathon runner. He was already 50 years old when he first participated in the famous South African Comrades double marathon. He would run (and finish!) it eight times.
Juan Heyns will be remembered as a great contributor to the science of nematology, as one of the rapidly dwindling number of nematologists with a broad knowledge of taxonomy. Above all, we will remember him as a very kind, often too modest, but always highly respected, scientist ready to listen to, to help and to stimulate students, collaborators and colleagues. His belief was that an example tells more than words and he was an example for many.
Having been associated with Juan in research for more than 20 years, having participated in joint collecting trips, safaris and bird watching excursions, we became very close friends and it is difficult not to become too personal. We have, often with both our families, shared many happy moments and it is hard to accept this has now come to an end.
Juan is survived by his wife Errie, his daughter Tessa, sons Louis and Anton and six grandchildren.
We will miss him during our future gatherings, but his memory will remain vivid to all those who have known him.