Molecular phylogeny of Cosmetocleithrum Kritsky, Thatcher & Boeger, 1986 (Monogenoidea: Dactylogyridae), gill parasites of Neotropical catfishes (Siluriformes)

Cosmetocleithrum Kritsky, Thatcher & Boeger, 1986 (Dactylogyridae) represents one of the most species-rich groups (22 species currently recognized as valid) of all dactylogyrid parasites infecting Neotropical catfishes. Species of Cosmetocleithrum exhibit a remarkable affinity towards catfishes of the Doradidae and the Auchenipteridae. However, phylogenetic relationships between members of this genus have not been yet analysed. This study analysed newly obtained partial sequences of the 28S ribosomal RNA gene of seven species of Cosmetocleithrum, including its type species C. gussevi Kritsky, Thatcher & Boeger, 1986, along with several other dactylogyrids infecting siluriform, gymnotiform, perciform and characiform fishes. Cosmetocleithrum appeared as an evolutionary recent group, composed of two well-defined lineages: lineage 1 includes parasites of doradids - namely, C. bulbocirrus, C. confusum, C. parvum and C. bifurcum - whereas lineage 2 is composed of species from doradids - that is, C. rarum, C. gussevi, C. gigas, C. trachydorasi and C. falsunilatum - together with parasites of auchenipterids - namely, C. laciniatum and C. baculum. The search for synapomorphies to characterize taxonomic groups within Cosmetocleithrum appears challenging, since the morphology of their haptoral elements is quite conservative, and that of the copulatory complex is highly variable between species. The results of the present study support the recent synonymization of Paracosmetocleithrum Acosta, Scholz, Blasco-Costa, Alves & Silva, 2018 with Cosmetocleithrum. Whereas the 28S ribosomal DNA data resolved Cosmetocleithrum as monophyletic, the statistical support for the lineage was low, rendering its phylogenetic position between other Neotropical dactylogyrids yet undefined.

Molecular characterization of Fasciola flukes using mitochondrial 28S rRNA gene in Naimi Saudi sheep

Fasciolosis is a parasitic disease of medical and economic importance. This retrospective study was conducted on 110 Fasciola flukes collected from livers of 14 infected Naimi sheep slaughtered at Riyadh abattoir in Saudi Arabia during winter season of 2016. Collected specimens were analyzed for their species identification on the basis of partial sequences of mitochondrial 28S rRNA gene. Results have shown the presence of both Fasciola hepatica (F. hepatica) and Fasciola gigantica (F. gigantica) species. Where Fasciola hepatica was predominate (80%). Both intra-species and interspecies genetic distance was studied and results showed that the intraspecific variability among individuals of both species i.e., F. hepatica and F. gigantica, ranging between 0 and 1% while the interspecific diversity between F. hepatica and F. gigantica was only 1%. In conclusion, mitochondrial 28S rRNA gene is a proved as a good marker in identifying Fasciola of different species. Where, the F. hepatica and F. gigantica are present in sheep breed in Riyadh region, Saudi Arabia.