Morphological Artifacts on Histologic Specimens of Paramphistomids (Trematoda, Paramphistomidae) and Their Role in Correct Diagnosis of Species

The introduction of a histological method into practice of species diagnostics of trematodes of the suborder Paramphistomata Skrjabin et Schulz, 1937, contributed to regular reports on the discovery of new trematode species in the family Paramphistomidae Fischoeder, 1901. At the same time, several new species were described based on identification of specific histological morphological characteristics which in fact turned out to be artifacts in subsequent detailed analysis. Based on this argument, paramphistomid species described in domestic literature sources, namely, Cotylophoron skrjabini, Cotylophoron vigisi, Ceylonocotyle petrowi, Liorchis hiberniae and Liorchis scotiae are considered as invalid. The cause of morphological artifacts on histological sections of paramphistomids are firstly non–standardized or incorrect primary treatment with fixing chemical agents of parasite isolates detected during necropsy in definitive hosts; secondly, errors in the implementation of general histological technique elements which in the applied approach are critically important and require the development of methodologic modernization adapted to work with biological objects with morphological traits; thirdly, incorrect subjective perception of histological artifacts, their false acceptance as distinctive species characters that have diagnostic value in taxonomy of the family representatives. It is necessary to develop optimized methodological techniques adapted to the applied purpose of teaching methods based on general histological technology elements the implementation of which will help to avoid morphological artifacts on histological sections of paramphistomids.