In 2018 and 2019, salmonid fishes, Salmo trutta L. and Salvelinus alpinus (L.) from lakes in Iceland were assessed for trematodes during a parasitological examination. Combined morphological and molecular analyses revealed the presence of four trematode species, two of which were previously known to parasitise salmonids in Iceland, Crepidostomum farionis (Müller, 1780) and Phyllodistomum umblae (Fabricius, 1780), and the two remaining species were recognised as new to science. Morphologically and genetically, Crepidostomum brinkmanni n. sp. and C. pseudofarionis n. sp. are closely related to two European species, namely C. metoecus and C. farionis. However, C. brinkmanni n. sp. is distinct by the position of maximum body width and arrangement of vitelline follicles; C. pseudofarionis n. sp. is distinct by its stout body, position of maximum body width, size of muscular papillae relative to oral sucker and the anterior extent of vitelline follicles. The new species were previously molecularly detected in their intermediate and definitive hosts in Norway and Ukraine, but their sequences were not supplemented with any morphological characterisation. In the present study, we provide detailed morphological descriptions and molecular sequences (28S rDNA and ITS2) of the four species of trematodes detected in Iceland. The discovery of the two new species of Crepidostomum indicates that the trematode diversity in fishes in the north is higher than previously known; our finding doubles the species spectrum of fish trematodes for Iceland. The record of C. brinkmanni from Ukraine indicates that its distribution might not be limited to northern latitudes.

• Keywords
• Allocreadiidae, Gorgoderidae, Morphology, Nuclear DNA, Sub-Arctic,
• MeSH
• Biodiversity * MeSH
• Species Specificity MeSH
• Phylogeny MeSH
• Trematode Infections epidemiology   parasitology   MeSH
• Lakes MeSH
• Fish Diseases epidemiology   parasitology   MeSH
• DNA, Ribosomal genetics   MeSH
• Salmonidae parasitology   MeSH
• Trematoda classification   genetics   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Iceland epidemiology   MeSH
• Names of Substances
• DNA, Ribosomal MeSH

Scanning electron examination of trematode specimens belonging to Nicolla skrjabini (Iwanitzky 1928), collected from brown trout Salmo trutta fario L. in the Czech Republic, made it possible to study their surface morphology including details not described previously. The tegument bears numerous characteristic papillae mainly around and inside the suckers and around the genital pore and minute sensory organs near the anterior body end. Surface morphology may prove to be useful in distinguishing Nicolla spp.

• MeSH
• Microscopy, Electron, Scanning MeSH
• Parasitic Diseases, Animal parasitology   MeSH
• Salmonidae parasitology   MeSH
• Fresh Water MeSH
• Trematoda classification   isolation & purification   ultrastructure   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Czech Republic MeSH