The Carpathian brook lamprey (Eudontomyzon danfordi Regan,
1911) is an endemic protected species of Cephalaspidomorphi in the Carpathian Basin.
No parasites have become known from these jawless vertebrates to date. Here, the authors
describe an infection from a single specimen manifesting in protuberant skin cysts
7–10 mm in diameter, scattered on the body surface. Similar dermal infection was observed
in 25 of the 274 lampreys recorded in the population survey. Skin cysts filled with
round spore‐like structures of a dermocystid parasite were found. These particles
measured 8–14 µm in diameter and had an about 0.5 µm thick wall, and containing mainly
a granular mass and a relatively scarce plasma. No hyphae were recorded. Despite conspicuous
morphological changes in the skin, no inflammatory reactions were found. The molecular
analysis of 18S rDNA showed similarity to dermocystid species of several fish species
but differed from them approximately by 2%. This is the first record of a dermocystid
parasite infecting a jawless vertebrate.
