Contributions to the knowledge of Atlantic Canadian Histeridae (Coleoptera)

New records of Histeridae from Atlantic Canada are reported. Three species are newly recorded from Prince Edward Island and two from New Brunswick, one of which, the introduced Palearctic Atholus bimaculatus (Linnaeus), is newly recorded from Atlantic Canada as a whole. These new records increase the known histerid fauna of the region to 37 species, 30 native and 7 introduced ones. The regional zoogeography of the Histeridae is examined focusing on differences between the faunal composition of the various provinces and the possible reasons responsible for these. The island faunas of Cape Breton, Prince Edward Island, and Newfoundland are examined. All have reduced faunas in comparison with the mainland perhaps as a result of island-associated diminutions, an area effect, a paucity of collecting, or a combination of these factors. Those of Cape Breton and Prince Edward Island are proportionately similar to those of other families of Coleoptera, whereas that of Newfoundland (only 10% of the mainland fauna) is significantly less, a circumstance which deserves further investigation. Seven species of introduced histerids have been recorded in the region. The average dates of first detection of these species are much later than the earliest records of these species in North America and comparatively later than is the case with other suites of introduced species in the Staphylinidae and Carabidae, perhaps as a result of the sparse attention the Histeridae have historically received by coleopterists in the region. Most of the introduced histerids are known to be synanthropic and may have been introduced to the region association with the importation of livestock and materials related to animal husbandry. The Histeridae of the region largely fall into one of several trophic guilds: coastal species and those associated with beach-drift material; species associated with bird nests; species associated with mammal nests; myrmecophilus species; saproxylic species found in sub-cortical environments; and generalist species found in a wide variety of decomposing situations.