The Gyrinidae (Coleoptera) of the Maritime Provinces of Canada: new records, distribution, and faunal composition

The Gyrinidae (whirligig beetles) of the Maritime Provinces of Canada are surveyed. Twenty-two species are now known to occur in the region, 19 of which have been recorded from Nova Scotia, 17 from New Brunswick, and 9 from Prince Edward Island. Seven species are newly recorded in Nova Scotia, and four in New Brunswick. Two of these, Gyrinus dichrous LeConte and Gyrinus gehringi Chamberlain, are newly recorded in the Maritime Provinces. The zoogeographic composition of the fauna within the region is briefly examined, the species falling into six categories. Islands portions of Atlantic Canada (Prince Edward Island, Cape Breton, and insular Newfoundland) have a diminished fauna, roughly 40% that of neighbouring mainland areas. The proportionate composition of the gyrinid fauna in various portions of Atlantic Canada is similar to that of the Carabidae (a much larger suite of beetles that have been more extensively investigated) with the exception of New Brunswick, where a diminished number of recorded gyrinids would appear to indicate an insufficient collecting effort for this family in the province. Finally, a preliminary examination of multispecies associations is presented which indicates that some species more frequently engage in such aggregations than others