Description of Gyrodactylus mediotorus n. sp. (Monogenea: Gyrodactylidae) infecting spottail shiner (Notropis hudsonius) from the St. Lawrence River, Canada.

Gyrodactylus mediotorus n. sp. is described from the body, fins, and buccal cavity of the spottail shiner, Notropis hudsonius (Cyprinidae) from the St. Lawrence River, Quebec, Canada. Gyrodactylus mediotorus n. sp. is the first species of Gyrodactylus Nordmann, 1832 described from N. hudsonius and is characterized by large hamuli, large medial process of the ventral bar, narrow linguiform ventral bar membrane, large anterolateral processes, and marginal hooks with long shafts and distinctly shaped sickle. The species that most resembles Gyrodactylus mediotorus n. sp. is Gyrodactylus protuberus Rogers and Wellborn, 1965 described from the stargazing shiner, Notropis uranoscopus Suttkus, 1959. The 2 species can be differentiated based on the larger hamuli (68.4 vs. 64) and ventral bar (38.4 vs. 24) of Gyrodactylus mediotorus n. sp. and the shape of the marginal hooks which for Gyrodactylus mediotorus n. sp. has a slightly larger toe and a point which is not as angled. The morphological description is supplemented with 436 sequenced base pairs of the 18S gene (including the V4 region) as well as 1,041 sequenced base pairs spanning the complete ITS-1, 5.8S, and ITS-2 regions. BLAST (Basic Local Alignment Search Tool) searches failed to provide any close matches for either regions of DNA, with Gyrodactylus colemanensis infecting Salvelinus fontinalis being the most genetically similar for both the 18S (∼91%, JF836090) and ITS (∼84%, JF836142) rDNA regions. Gyrodactylus mediotorus n. sp. has been found infecting spottail shiners in the St. Lawrence River in low prevalence and intensities periodically over the last 15 yr.

Description of Gyrodactylus notatae n. sp. (Monogenea: Gyrodactylidae) from Menidia menidia (L.) (Actinopterygii: Atherinidae) in Nova Scotia, Canada.

Gyrodactylus notatae n. sp. (Monogenea: Gyrodactylidae) is described from the fins and gills of the Atlantic silverside Menidia menidia (L.) (Atherinidae) inhabiting the brackish water of Lawrencetown Lake, Nova Scotia, Canada. G. notatae n. sp. is the first monogenean to be reported from M. menidia. It is characterised by having stout hamuli, a ventral bar with small anterolateral processes and a linguiform membrane, a cylindrical dorsal bar, a male copulatory organ (MCO) with a single large and only three small terminal spines, and a marginal hook sickle that is wider distally than proximally. The new species most closely resembles species of the G. wageneri-group, particularly G. pungitii Malmberg, 1964, but is distinguished by the smaller dimensions of all of its haptoral components. The morphological description of G. notatae is supplemented with 1,028 sequenced base pairs (bp) of ribosomal DNA (rDNA) spanning the ITS-1, 5.8S and ITS-2 regions, with which a BLAST (Basic Local Alignment Search Tool) search failed to provide close matches (c.80%). G. notatae is only the second species of viviparous monogenean to be described from species of Menidia, the other being G. nannus Rogers, 1968 from M. beryllina (Cope) in the southern USA. The two species appear to be from different lineages within Gyrodactylus von Nordmann, 1832.

Occurrence of Glugea pimephales in planktonic larvae of fathead minnow in Algonquin Park, Ontario.

The microsporidian Glugea pimephales was found parasitizing larval fathead minnow Pimephales promelas in Scott Lake, Algonquin Park, Ontario. These fish were estimated to be 2-3 weeks posthatch and, given the development time of the parasite, must have acquired infection soon after commencement of exogenous feeding. Histological sections revealed that the parasite typically developed in loose connective tissue between the peritoneum and the dermis of the abdominal cavity, with protruding xenomas of up to 2.6 mm in diameter forming near the vent. Prevalence was estimated at 1% by divers performing snorkel surveys along the lake shoreline. Divers following schools of fathead minnow consistently reported that larvae with the obvious cysts wobbled during swimming and that infected fish were typically located at the back of the dispersing school. This case history joins a growing list of studies suggesting that fish can become infected with parasites soon after hatch, the potential importance of which has not been critically studied.