New distribution records for Canadian Aleocharinae (Coleoptera, Staphylinidae), and new synonymies for Trichiusa.

Fifty-four new Canadian provincial records of aleocharine beetles (Staphylinidae), including three new Canadian records and one new North American record, are presented. Of these, 33 are new provincial records for Saskatchewan, 14 for Alberta, two for British Columbia, three for Manitoba, two for the Northwest Territories and one for the Yukon Territory. The following are new Canadian records: Trichiusapilosa Casey [formerly reported from Nova Scotia and Ontario as Trichiusapostica Casey], Acrotonarecondita (Erichson) and the adventive Palaearctic Athetanigra (Kraatz), which is also a new North American record. Bionomics information and new locality records are provided. The following new synonyms of Trichiusapilosa Casey are established: Trichiusaatra Casey, Trichiusamonticola Casey, Trichiusaparviceps Casey, and Trichiusapostica Casey. The numbers of Aleocharinae remaining to be discovered in Canadian provinces and territories are discussed.