Adult trematodes of Allocreadium Looss, 1900 (Digenea) infect the intestine of mostly freshwater fishes in Asia, Europe, Africa and the Americas. During routine parasitological surveys in the Vaal River system, adult trematodes were collected from the intestine of smallmouth yellowfish, Labeobarbus aeneus (Burchell). The trematodes were confirmed to represent a member of Allocreadium and did not match any existing taxon. Therefore, they are described as a new species, Allocreadium apokryfi sp. n. The morphology of the new species most closely resembles that of Allocreadium aswanense El-Naffar, Saoud et Hassan, 1984, but it differs from it by having a bipartite internal seminal vesicle, wider eggs, a shorter intertesticular distance, an intestinal bifurcation at the ventral sucker level, a ventral sucker that is larger than the oral sucker, and a genital pore near the intestinal bifurcation or the ventral sucker. The surface topology of the new species is notably different from that of other allocreadiids. Papillae were observed in the ventral sucker and surrounding both ventral and oral suckers, but the number and arrangement of the latter were not consistent among specimens. The protruding cirrus of A. apokryfi sp. n. was described using SEM and is the first such observation for the genus. Genetic characterisation showed that the new species was clearly distinct from other Allocreadium spp. using both 18S (nucleotide difference 1.3-9.1%) and 28S (4.7-6.5%) rDNA, forming a well-supported clade in Allocreadium. The presence of A. apokryfi sp. n. in a well-studied river is unexpected, and considering the diet of its host and the scarcity of Allocreadium in Africa, the possible biology of this species is discussed herein.
This is the first study detailing the microhabitat specificity of the monogenean parasite, Paradiplozoon ichthyoxanthon Avenant-Oldewage in Avenant-Oldewage et al., 2014. Samples of the monogenean were collected from the gills of the smallmouth yellowfish Labeobarbus aeneus (Burchell) from the Vaal Dam, South Africa, over four seasons with the use of gill nets. Host condition factor fluctuated between the different seasons, with the highest values recorded in summer. Adults and diporpas of P. ichthyoxanthon were found in all four seasons. Adult parasites predominantly infect the first gill arch, whereas diporpas were found on the second and fourth arches. In utero eggs were also found throughout the sampling seasons and their number negatively correlated with the condition factor of the host. The occurrence of adults and diporpas of P. ichthyoxanthon correlated with the size of the host but not the condition factor. Water quality of the study site also had little correlational relationship with the occurrence of the parasites and fluctuations were related to season. The main factor that may drive the microhabitat specificity of P. ichthyoxanthon is the flow of water over the surfaces of the gills and chances of the parasites becoming dislodged. Size of the attachment organs has also been shown to play a role in this specificity, because smaller attachment structures favour stronger holdfast to areas where flow might be stronger compared to larger attachment structures., Beric M. Gilbert, Annemariè Avenant-Oldewage., and Obsahuje bibliografii