Prior to earning his PhD in 1929 from Budapest University, he spent a year in Cairo to help organize a botanical museum.
Gyelnik prefixed Kőfaragó (meaning "stone-cutter") to his name in 1935, and eventually became the head of the Botanical Department of the museum in 1942.
[3] Gyelnik published about 100 papers on lichens in the period 1926 to 1945, and proposed hundreds of new names, particularly in the genera Alectoria, Nephroma, Parmelia, and Peltigera.
[2] Ana Crespo and colleagues expressed a similar sentiment: "He was generally viewed as something of a nomenclatural terrorist by his contemporaries who were infuriated by the large numbers of novel taxa he described, most of which they could not accept, and an apparent slackness in how he worked".
[5] However, Hale also noted his deep understanding of the genus Xanthoparmelia and suggested that he was ahead of his time for using chemical tests and various morphological characters in devising his own classification system for European parmelioid lichens – some of which were used to define genera many decades later.