Introduction

The genus Xantholinus Dejean (Staphylininae: Xantholinini) is a diverse, mainly Palearctic group and contains several species that prefer open, disturbed areas, where they often dominate the staphylinid assemblage (Daccordi and Zanett 1989; Balog and Marko 2007). These habits have likely facilitated the accidental importation and subsequent establishment of Xantholinus species into North America. Smetana (1982) reported Xantholinus linearis (Olivier, 1795) from both eastern and western portions of the North America and Xantholinus longiventris (Olivier, 1795) only from western regions. Since then, several publications have presented either new provincial and state records, or additional locality data for these two species (Smetana 1988, 1990; Majka and Klimaszewski 2008a; Majka et al. 2008).

Recent collections and surveys in Ontario have resulted in the recognition of one additional species in North America and a range extension for Xantholinus linearis. We here summarize all available data for Xantholinus species in North America, present distributional maps, and provide a key for identification of the species known from the continent.

Material and methods

The aedeagus of Xantholinus elegans (Olivier, 1795) was prepared for examination as in Smetana (1982) and photographed using an imaging system by Visionary Digital. The specimen photograph of Xantholinus elegans was taken with the same system. Maps were created using ARC-GIS and Abode Photoshop software. The institutions (and their abbreviations) from which material was examined are as follows:

ACPE Agriculture and Agri-Food Canada, Prince Edward Island, Canada (Christine Noronha)

CBU Cape Breton University, Sydney, Nova Scotia, Canada (David. B. McCorquodale)

CGMC Christopher G. Majka Collection, Halifax, Nova Scotia, Canada (Christopher G. Majka)

DEBU University of Guelph, Guelph, Ontario (Stephen Marshall)

DENH University of New Hampshire, Durham, New Hampshire, USA (Donald Chandler)

DHWC David H. Webster Collection, Kentville, Nova Scotia, Canada (David. H. Webster)

NBM New Brunswick Museum, Saint John, New Brunswick, Canada (Donald McAlpine)

NSMC Nova Scotia Museum, Halifax, Nova Scotia, Canada (Christopher G. Majka)

NSNR Nova Scotia Department of Natural Resources, Shubenacadie, Nova Scotia, Canada (Jeffrey Ogden)

SMU Saint Mary’s University, Halifax, Nova Scotia, Canada (Doug Stongman)

UMNB Université de Moncton, Moncton, New Brunswick, Canada (Pauline Duerr)

Results Discussion

Xantholinus elegans is certainly a recent accidental introduction to North America as it was not included in Smetana (1990), and the earliest specimen known is from 2007. In its native range, Xantholinus elegans is distributed widely in the western Palearctic region and recorded from Austria, Belgium, Bosnia Herzegovina, Czech Republic, France, Great Britain, Germany, Hungary, Ireland, Italy, Luxembourg, The Netherlands, Poland, Slovakia and Spain (Smetana in Löbl and Smetana 2004). In Europe, it prefers sandy soils and is a bivoltine species with most adults collected in spring and late summer (Daccordi and Zanetti 1989; Drugmand 1994). While most North American specimens were found on sandy soil, adults were collected throughout the summer and sparingly in spring and fall. Further collecting should help determine whether this is a collecting artefact or a shift in seasonality in response to a different geographic area. The majority of specimens have been collected in disturbed habitats and it is unknown if this species will invade habitats with little to no recent human disturbance. It is unclear whether the easternmost record (Marmora) (Fig. 1) represents an isolated population as a result of human-aided dispersal, or if it indicates an inadequately sampled, broader distribution in southern Ontario.

The method of introduction is unknown but may be related to the importation of plant stock or associated materials as Xantholinus linearis was intercepted twice in soil with primrose and moss shipments from Europe in the 1930’s (Smetana 1982). Other predatory beetles are suspected to have become established via plant stock importation (Spence and Spence 1988). Although exotic staphylinids are typically considered to enter eastern North America via Atlantic Canadian introduction points in Nova Scotia, Newfoundland, and in Massachusetts – many associated with historic shipments of dry ballast material (Smetana 1995; Majka and Klimaszewski 2008b) – examination of recent material from the University of New Hampshire Insect Collection and numerous collections in Maritime Canada have not turned up specimens of this species. It appears that the North American occurrence of Xantholinus elegans represents an inland introduction, similar to that of the Emerald Ash Borer, which was first detected in Michigan/southern Ontario in 2002 (Poland et al. 2006). Although Xantholinus elegans is a brachypterous species (Assing 1993; Drugmand 1994) and is unable to disperse aerially, other beetles introduced to North America were found to disperse readily, despite their brachyptery (Spence and Spence 1988). The availability of suitable, open habitat in eastern North America may provide for the expansion of its range to include regions other than Ontario.

Xantholinus linearis was considered to be well-established in both eastern and western North America by Smetana (1982, 1988, 1990) and data presented in this paper demonstrate that it is continuing to expand its range towards the centre of the continent. This species was previously known from British Columbia, Nova Scotia, New Brunswick, Newfoundland and Prince Edward Island in Canada, and California, Idaho, Massachusetts, New Hampshire, Nevada, Oregon, Rhode Island, Utah, and Washington in the United States (Smetana 1982; Smetana 1990; Chandler 2001; Sikes 2003; Majka and Klimaszewski 2008a; Klimaszewski et al. 2010). While it has been known from Atlantic Canada since 1949, it appears to have only recently reached Ontario, as it is missing from collections made prior to 2008. Specimens from Pennsylvania and New York were clearly stated as ‘interceptions’ by Smetana (1982) and should not be considered as evidence that this species occurs there. Interestingly, recent surveys of open field habitat in both these states have not detected Xantholinus linearis (Byers et al., 2000). Further survey work is needed to fully delimit the eastern range of this species.

Xanthlinus longiventris is still known only from the western United States (California, Oregon, Washington) and has not been reported from additional states or any provinces since it was treated in Smetana (1982). In North America, habitat data from specimens suggests that Xantholinus longiventris, while it often co-occurs with Xantholinus linearis, prefers a higher level of moisture (in moss, near water etc.) as it has not been collected from drier urbanized places where the latter species is often found. This species’ range in North America is probably confined by the Rocky Mountain system and will likely remain stable in the absence of secondary introductions.

Three species of Xantholinus are now known to have established themselves in North America via human activity. Of these, at least Xantholinus linearis is apparently continuing to expand its distribution towards the centre of the continent and may be detected in additional provinces and states in the future. This paper provides a current synthesis of distributional information and facilitates the identification of a previously unrecognized species for the North American fauna. A complete review and identification manual for the entire Xantholinini in eastern North America is currently in preparation.