Contributions to the faunistics and bionomics of Staphylinidae (Coleoptera) in northeastern North America: discoveries made through study of the University of Guelph Insect Collection, Ontario, Canada Author Brunke, Adam J. Author Marshall, Stephen A. text ZooKeys 2011 75 29 68 http://dx.doi.org/10.3897/zookeys.75.767 journal article http://dx.doi.org/10.3897/zookeys.75.767 1313-2970-75-29 Stenus clavicornis (Scopoli, 1763) Materials. UNITED STATES: MA:Middlesex Co., Groton, 30-IV-2010, T. Murray, (1). CANADA: ON:Halton Reg., Milton, Derry Rd. and 4th line, grass field, yellow pans, 23 to 24-VI-2001, S. Paiero, (1); Huron Co., Auburn, Hullett-McKillop Rd. nr. Limekiln Line, 43.744, -81.507, soybean field, pitfall, 4-VIII-2010 (1), A. Brunke; Auburn, Limekiln Line, 43.736, -81.506, hedgerow, pitfall, 26-V-2010 (1), A. Brunke; Benmiller, Sharpes Creek Line, 43.691, -81.608, hedgerow nr. creek, canopy trap in buckthorn, 11-V-2009 (2), A. Brunke;Brucefield, London Rd. nr. Centennial Rd., 43.509, -81.516, hedgrerow nr. creek, pitfall, 11-V-2009 (1), A. Brunke; Ottawa, Carleton Place, 12-IX-1992, W. Bennett, (1); Peel Reg., Cooksville, pond margin, 30-V-1993, C. Krupke, (1); Waterloo Reg., Blair, Whistlebare Rd. and Township Rd.1, 43.372, -80.362, hedgerow, pitfall, 18-V-2010 (1), A. Brunke; Wellington Co., Guelph, 10-IX-1980, Y. Deedat; Guelph, 17-IX-1980, Y. Deedat; Guelph, University Arboretum, 1-X-2005, M. Bergeron, (1); Guelph, Victoria Rd. and Conservation Line, 43.580, -80.275, soybean field, canopy trap, 23-VI-2009 (1), A. Brunke; York Reg., Stouffville, V-1982, Brian Brown, (1); Diagnosis. Stenus clavicornis is, at present, only reliably distinguished from congeners in North America by its characteristic aedeagus (Fig. 14). Maps 13-16. Distribution in northeastern North America, sources of data other than DEBU are quoted in parentheses. 13 Stenus clavicornis (Scopoli) ( Puthz 1975 , Puthz 1994 , Campbell and Davies 1991 , Chandler 2001 , Majka and Klimaszewski 2008a , Klimaszewski et al. 2010 ) 14 Eustilicus tristis (Melsheimer) ( Melsheimer 1884 , Sanderson 1947 , Herman 1970 ) 15 Medon fusculus (Mannerheim) ( Campbell and Davies 1991 ) 16 Scopaeus minutus Erichson ( Frisch et al. 2002 ). This exotic, Palaearctic species was first recognized in North America by Puthz (1975) based on specimens collected in Quebec as early as 1968 in Orsainville. Since then it has been detected in New Brunswick ( Campbell and Davies 1991 ), Prince Edward Island ( Klimaszewski et al. 2010 ), New Hampshire, Pennsylvania ( Puthz 1994 ), Maine ( Chandler 2001 ), and Nova Scotia ( Majka and Klimaszewski 2008a ). Herein we report Stenus clavicornis from Ontario and Massachusetts on the basis of specimens collected as early as 1980 and 2010, respectively (Map 13). Its native range is very broad and includes most of the Palaearctic region ( Smetana in Loebl and Smetana 2004 ). In North America, this species has been collected from a variety of habitats including open fields, agricultural land, woodlots, and the margins of ponds and salt marshes.