Reinhold Johannes Ortlepp (later affectionately known as "Oom Rein"), son of Frederick Ortlepp and his wife Johanna, born Doyer, matriculated at Maritzburg College, Pietermaritzburg, in 1911. He started his university education at the Natal University College the next year, but continued his studies at Victoria College, Stellenbosch, from 1913. Upon receiving the BA degree with distinction from the University of the Cape of Good Hope he was awarded the Queen Victoria bursary, which enabled him to obtain the MSc degree in zoology at the University of Cape Town in 1917. The next year he published his first scientific paper, "Note on the persistence of the right posterior cardinal vein in Xenopus laevis, and its significance" (Report of the South African Association for the Advancement of Science, 1918, pp. 413-415). After a year as lecturer in zoology at the South African School of Mines and Technology (later the University of the Witwatersrand) during 1918-1919, and another year as acting professor of zoology at Rhodes University College in 1920, he proceeded to London in 1921 as researcher at the Institute for Agricultural Parasitology. During his vacations he spent some time at research institutes in Neuchatel, Vienna and Naples. Concentrating on the study of wormlike parasites obtained from South African mammals, reptiles and amphibians in the London zoo, he discovered and described nine new species and became honorary helminthologist to the Zoological Society of London. In 1923 he was awarded a PhD in zoology (helminthology) by the University of London, but stayed on in his research post until the end of 1927.
Ortlepp returned to South Africa in 1928 and after a short spell farming in Natal was appointed in 1930 as research officer at the Onderstepoort Veterinary Institute. Here he succeeded P.L. le Roux* as researcher on helminths and remained for the rest of his career. His speciality was the taxonomy and life cycles of the Trematoda, Cestoda and Nematoda and during the next 30 years he discovered and described 100 new species. The University of London awarded him a DSc degree in 1936. During his later years, after retiring in 1954, he turned his attention more specifically to the internal parasites of wildlife. He had 70 scientific publications to his credit.
Ortlepp was a foundation member of the Fakulteit Natuurwetenskap en Tegniek of the Suid-Afrikaanse Akademie vir Wetenskap en Kuns and in 1948 the Akademie awarded him the Havenga prize for biology. He became a member of the South African Association for the Advancement of Science in 1931 and was president of its Section D in 1943. After joining the South African Biological Society in 1936 he served as its president in 1940 and received its Senior Captain Scott Medal in 1962. His other activities included membership of the Scientific Advisory Board for National Parks, the Fauna and Flora Advisory Council of the Transvaal, the Bilharzia Research Committee of the Council for Scientific and Industrial Research (until its dissolution in 1962), and the Scientific Section of the National Advisory Board for Education. He also served on the Executive Committee of the Natal Agricultural Union from 1929 to 1931, the last year as president. During his career he acquired an extensive library which he bequeathed to the Section of Helminthology at Onderstepoort.
Ortlepp was survived by his wife, Adriana Maria Ortlepp, born Potgieter, and three children.