text:
p53, a potential predictor of Helicobacter pylori infection-associated gastric carcinogenesis?

Helicobacter pylori (H. pylori) is an ancient and persistent inhabitant of the human stomach that is closely linked to the development of gastric cancer (GC). . Emerging evidence suggests that H. pylori strain interactions with gastric epithelial cells subvert the best- characterized p53 tumour suppressor pathway. A high prevalence of p53 mutations is related to H. pylori infection. H. pylori also accelerates p53 protein degradation by disturbing the MDM2-P53 feedback loop. Additionally, H. pylori triggers the alteration of other p53 isoforms. Dysregulation of p53 by H. pylori infection contributes to gastric carcinogenesis by mediating cell proliferation and apoptosis. This review focuses on the regulation of p53 in H. pylori infection-associated GC.

INTRODUCTION
Helicobacter pylori infection is a strong risk factor for gastric cancer (GC). The International Agency for Research on Cancer (IARC) classified this bacterium as a Group I carcinogen. Epidemiological studies indicate that approximately 50% of the global population is infected with H. pylori, which is primarily acquired during childhood [1][2][3]. H. pylori uses various virulence factors in gastric epithelial cells to target different signalling pathways that regulate specialized survival programs, such as the cell cycle and apoptosis. Vacuolating cytotoxin gene (vacA) and cag pathogenicity island (cagPAI) are the best characterized virulence factors [4]. cagPAI encodes a type IV secretion system (T4SS) that delivers the oncoprotein CagA into host cells.
Chronic inflammation results from the virulence factor CagA and is recognized as the underlying mechanism of H. pylori-associated gastric carcinogenesis [5]. Accumulating data demonstrate that CagA injection into host cells stimulates the recruitment of inflammatory cells and the production of cytokines, including interleukin (IL)-1β and IL-8, as well as the activation of Wnt/βcatenin signalling via the nuclear accumulation of betacatenin in epithelial cells [6][7][8]. H. pylori also promotes PI3K/AKT, mTOR, and p38/MAPK signalling, and these oncogenic signalling pathways alter cellular oncogenes and tumour suppressors. H. pylori also disrupts cell-cell junctions and cell polarity via inhibition of the PAR-1/ MARK complex [9,10]. H. pylori infection causes DNA double-strand breaks (DSBs) and genomic instability via the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) [11,12]. Together, recent studies have shown that the regulation of p53 is involved in gastric carcinogenesis caused by H. pylori infection.
The pathogenic bacterium H. pylori modulates the host p53 pathway by controlling various cellular stresses, including DNA damage, ROS and RNS production, and abnormal oncogene activation. Frequent p53 gene mutations are also detected in gastric pre-neoplastic lesions, which more broadly suggests an association between p53 and disturbances in cell proliferation and apoptosis in gastric epithelial cells infected with H. pylori. This review focuses on H. pylori infection-mediated p53 regulation because of the central role of p53 in H. pyloriinduced gastric carcinogenesis. Thus, p53 may serve as a novel biomarker and therapeutic target for GC.

TUMOUR SUPPRESSOR P53
The human tumour suppressor gene p53, also known as TP53, was first identified in 1979 as a cellular protein bound to immunoprecipitates of the SV40 LT protein in SV40 tumour virus-transformed cells [13]. The p53 is Review present at extremely low levels in normal cells, but these levels increase significantly in response to DNA damage or other types of cellular stress [14]. In particular, DNA damage induces the stabilization and nuclear accumulation of p53 via the DNA damage signalling pathway, which involves sensor kinases such as ataxia-telangiectasia mutated (ATM) and ataxia-telangiectasia and Rad3-related (ATR) [15,16].
p53 is known as the "guardian of the genome" because it repairs DNA and maintains genomic stability after DNA damage. The ubiquitin ligases murine double minute (MDM2, also known as HDM2) and ARF-BP1 are crucial negative regulators of p53 that drive its rapid degradation [17,18]. Notably, p14ARF regulates the transcriptional activity of p53 by antagonizing MDM2. The p53 protein functions as a transcription factor that promotes cell cycle arrest at the G1 phase via upregulation of the expression of an inhibitor of cyclin-dependent kinase, p21. p53 also induces cell apoptosis via two apoptotic pathways, the mitochondrial pathway, which mediates the expression of B-cell lymphoma 2 (Bcl-2) family members, and the death receptor pathway, which triggers activation of the caspase cascade [19][20][21] (Figure  1). Indeed, approximately 50% of all cancers exhibit a mutation in p53 [22]. In vivo assays have shown that mice expressing a mutant p53 protein exhibit more aggressive and metastatic tumours compared to p53 wild-type (WT-p53) mice [23]. These findings suggest that the mutation of p53 during tumourigenesis represents an essential step in the switch to aggressive tumour development. Figure 1: Regulation of p53 and its key regulators in response to DNA damage. DNA damage triggers the activation of the tumour suppressor protein p53 via ataxia-telangiectasia mutated (ATM) and ataxia-telangiectasia and Rad3-related (ATR) protein kinase-dependent pathways, which leads to cell cycle arrest via the induction of the cyclin-dependent kinase (CDK) inhibitor p21 and cell apoptosis via mediation of Bcl-2 family expression. MDM2 (also known as HDM2) and ARF-BP1 act as E3 ubiquitin ligases that target p53 proteasomal degradation, which ensures low p53 levels in normal and unstressed cells. Notably, the tumour suppressor p14ARF protects p53 protein stability via inhibition of MDM2/HDM2 and ARFBP1. www.impactjournals.com/oncotarget

EXPRESSION OF P53 IN H. PYLORI-INFECTED PATIENTS WITH GASTRIC CARCINOGENESIS
GC is divided into three pathological variants: intestinal type, diffuse type and mixed type [24,25]. H. pylori has been identified as the strongest risk factor of intestinal type GC, which may progress from atrophy gastritis to intestinal metaplasia, dysplasia and eventually carcinoma [26]. Some investigations have detected p53 expression in the gastric mucosa of patients with pre-neoplastic lesions infected with H. pylori, including atrophy and intestinal metaplasia [27,28]. Immunohistochemical analyses of p53 in CagA-positive H. pylori gastritis patients prior to gastric metaplastic/ dysplastic changes have revealed increased p53 expression but decreased apoptosis, and one possible cause for this association is the detection of mutant p53 protein [29]. p53, p21 and Ki-67 expression were examined using immunohistochemical staining in volunteers from the general Spanish population. The subjects with H. pylori infection exhibited significantly higher p53 levels and mucosal proliferative activity compared to the uninfected subjects, and this association was primarily related to cardia-type mucosa rather than corpus [30].  epithelial cells using a type IV secretion system (T4SS), which is responsible for alterations of the tumour suppressor p53. Chronic H. pylori infection may cause an accumulation of mutant p53. H. pylori also increases MDM2 levels via multiple mechanisms that target the proteasome-mediated degradation of p53. The CagA protein also binds to the apoptosis-stimulating protein of p53 (ASPP), which consequently hinders the interaction between ASPP2 and p53. Other isoforms of the p53 family, including p63, p73, ∆133p53 and p53 14-3-3 protein isoforms, are also involved in the regulation of p53 by H. pylori. In summary, long-term infection with H. pylori is responsible for reducing the levels of p53, which contributes to the development of gastric carcinoma.
Wild-type p53 protein is relatively unstable and generally not detectable. In contrast, mutant p53 exhibits a much longer half-life, and immunohistochemical staining of p53 is commonly used as a surrogate for mutational analyses [32]. Gastric biopsy samples from gastritis, intestinal metaplasia and GC patients were collected to measure p53 expression levels in gastric carcinogenesis related to H. pylori infection. p53 protein exhibited a significantly higher degree of staining in H. pylori-positive GC samples; specifically, p53-positive cells were identified in 0% of control samples, 0% of gastritis samples, 13.3% of intestinal metaplasia samples and 43% of GC samples [33,34]. These results suggest that alteration of p53 may be an early event in H. pyloriassociated gastric carcinogenesis.

P53 GENE MUTATIONS RELATED TO H. PYLORI INFECTION
Inactivation of the tumour suppressor p53 is a hallmark of tumourigenic changes. Accordingly, the p53 gene is aberrantly expressed in nearly half of all human cancer cell genomes. Mutant p53 proteins acquire tumour-promoting functions that enhance cell growth, proliferation, survival, and motility [35, 36] p53 mutations are generally divided into two categories: DNA-interacting mutants that directly alter amino acids and structural mutants that lead to the unfolding of p53 protein, which is critical for tumours to gain tumour-associated functional phenotypes [37,38]. Notably, the primary alterations of p53 occur primarily in highly conserved domains, especially amino acid substitutions, including R175, G245, R248, R249, R273 and R282. Some mutant p53 proteins that recognize a unique response element acquire properties of an oncogenic transcription factor. Mutant p53 was experimentally demonstrated to deregulate checkpoints of cell cycle responses to the induction of DNA damage, which accelerated tumour progression via the promotion of genomic instability, cell proliferation and invasion [39,40].
Numerous studies have shown that H. pylori infection is associated with a higher prevalence of p53 mutation. Indeed, an increasing frequency of p53 alterations occurs in neoplastic gastric lesions ranging from gastritis through dysplasia, intestinal metaplasia ( IM ) and advanced GC [41][42][43]. H. pylori is the strongest risk factor for GC, and this infection is known to enhance p53 mutagenesis. Lopez-Saez et al. found that 81% of the H. pylori-associated GC deaths in Spain were associated with increased mutant p53 protein compared to 11% in the H. pylori-negative group [44]. H. pylori infection may also contribute to the development of gastric adenocarcinoma by elevating mutant p53 protein [45]. The accumulation of mutant p53 may be attributed to the production of free radicals, such as ROS and RNS [46]. The combination of whole-exome sequencing with deep sequencing revealed that C:G>T:A transitions at XpCpG trinucleotides were the most common accumulation pattern of TP53. A total of 105 GC specimens from a high-risk area in Italy were examined for the prevalence of p53 mutations [47]. Notably, an association of H. pylori infection with p53 mutations was also apparent at CpG sites [47].
Mutations of p53 in exon 5-8 nucleotide sequences have also been widely studied in primary gastric adenocarcinoma with H. pylori infection [48]. Nucleotide sequencing analyses demonstrated the induction of several point mutations in exons 5, 6, 7 and 8 of the p53 gene in H. pylori-infected monkeys compared to H. pyloriuninfected monkeys, and p53 gene mutations were closely related to the degree of gastric mucosa atrophy [49]. Alterations in exons 5-8 of the p53 gene were also observed in H. pylori-positive patients with GC and peptic ulcer disease (PUD) [50,51]. The well-characterized factor CagA is an important virulence determinant in the gastric carcinogenesis of H. pylori infection. Notably, the p53 gene is more likely to harbour p53 mutations in gastric tumours with CagA-positive H. pylori strains. Recent studies suggest that gastric epithelial cells infected with CagA-positive H. pylori induce the expression of cytidine deaminase (AID), which may be a mechanism of p53 mutation accumulation during H. pylori-associated gastric carcinogenesis [28,52].

P53 CODON 72 POLYMORPHISMS
Several polymorphic sites in the tumour suppressor p53 are closely associated with various cancer risks. The codon 72 polymorphism that produces variant genotypes with arginine (Arg) or proline (Pro) is a frequently reported polymorphism site [53][54][55]. Hiyama et al. demonstrated that Pro/Pro genotypes at the p53 codon 72 polymorphism contribute to susceptibility to diffuse-type gastric carcinoma in patients with chronic gastritis [56]. One study reported that the polymorphism is related to lower TP53 transcriptional levels [55]. The distribution of the p53 codon 72 polymorphism varies in different regions worldwide. PCR-Taqman assays identified the Arg/Pro genotype of the p53 codon 72 polymorphism in 140 patients with gastric carcinoma from the GanSu province in China, where the GC incidence is high, and the p53 codon 72 Pro carrier genotype with H. pylori infection was consistently higher in GC groups than controls [57]. The p53 Pro/Arg and p53 Arg/Arg single-nucleotide polymorphism (SNP) variants were also significantly more common than the p53 Pro/Pro variant in a population from North India, which exhibits a high prevalence of H. pylori infection but low GC incidence. Therefore, the Arg or Pro/ Arg polymorphism may underlie these differences [58]. www.impactjournals.com/oncotarget

REGULATION OF THE P53-MDM2 FEEDBACK LOOP
The p53 pathway is extremely sensitive to DNA double-strand breaks (DSBs) and single-stranded DNA (ssDNA) gaps, which are created by a variety of DNA-damaging agents, including ionizing radiation, chemotherapeutic drugs and ultraviolet (UV) radiation [59,60]. The transcription-activating powers of p53 depend on the regulation of ATM and ATR protein kinases, which transfer the p53 signals to cell cycle checkpoint 1 (Chk1) and cell cycle checkpoint 2 (Chk2) kinases and lead to the phosphorylation of p53 to protect it from destruction by the specific E3 ubiquitin ligase murine double minute 2 (MDM2) [61,62].
The MDM2 protein has emerged as a crucial regulator of p53 tumour suppressor function. MDM2 binding to p53 immediately induces proteasome degradation of p53 and blocks p53-driven transcription [17,63]. The underlying molecular mechanism of MDM2 regulation of p53 degradation has been elucidated; MDM2 binds to the N terminus of p53 and promotes its export from the nucleus to cytoplasm, which results in its rapid degradation in cytoplasmic proteasomes [64]. p53 elements are located in the promoter of MDM2, and p53 induces the expression of MDM2. Therefore, a negative feedback loop exists between p53 and MDM2 that ensures low cellular p53 levels in normal and unstressed cells [65].
The amplification and overexpression of MDM2 are frequently observed in a variety of human cancers [66,67], and H. pylori also suppresses p53 through multiple mechanisms [68]. This bacterium contributes to proteasomal degradation of p53 by increasing the phosphorylation of the E3 ubiquitin ligase MDM2 [69,70]. Indeed, elevated levels of MDM2 are found in H. pylori-infected intestinal metaplasia and GC [71]. p53 was also shown to be upregulated in a bimodal fashion over time in Mongolian gerbils, which are the most suitable laboratory animal model for the study of H. pylori infection [69,72]. Acute accumulation of p53 was observed in response to cellular stressors after initial H. pylori infection, with subsequent rapid downregulation of p53 in the gastric mucosa; a second peak of p53 occurred after gastritis development [73]. These studies suggest that alterations in p53 expression profiles depend on the duration of H. pylori infection.

UPSTREAM REGULATORS OF THE MDM2-P53 FEEDBACK LOOP IN THE PATHOGENESIS OF H. PYLORI
H. pylori infection increases the phosphorylation and activation of AKT and MDM2 to downregulate p53, which results in the inactivation of p53 by increased ubiquitination and proteasome degradation [74,75]. Our previous studies investigated the correlation between protein expression in the AKT-MDM2-p53 pathway and H. pylori infection in chronic non-atrophic gastritis (CNAG), metaplastic atrophy (MA), gastric dysplasia (Dys) and GC patients. Notably, higher levels of mutant p53 and MDM2 were observed in H. pylori-positive patients with MA and Dys, and the expression of phosphorylated AKT was upregulated in CNAG patients with H. pylori infection. The expression of pAKT and MDM2 was also significantly increased after H. pylori strains were co-cultured with GES-1 gastric epithelial cells, which also supports the degradation of p53 [76,77]. Inhibition of MDM2 activity using siRNA or the inhibitor Nutlin3 in AGS human GC cells clearly inhibited the downregulation of H. pylori-induced p53. Notably, the bacterial protein CagA plays an important role in the alteration of p53 protein, as ectopic expression of CagA is sufficient to enhance AKT and MDM2 activity and induce p53 degradation [73,77].
ERK kinase interactions with HDM2 are responsible for p53 activity in H. pylori-infected cells [78], and experimental inhibition of ERK/MDM2 interactions was shown to rescue p53 activity and dampen damaged cell survival [79]. The intercellular junction protein E-cadherin, which maintains the epithelial barrier, was also upregulated in these gastric epithelial cells. AKT and ERK contribute to MDM2 activation in the setting of H. pylori infection, which leads to degradation of the p53 protein. Notably, p53 was dynamically altered in gastric epithelial cells co-cultured with H. pylori, which suggests a crucial role of the p53-MDM2 feedback loop [80].
P14ARF inhibits cell proliferation in a p53dependent manner. Specifically, p14ARF segregates MDM2 in the nucleolus and antagonizes the E3 ubiquitin ligase-mediated p53 protein degradation [81,82]. H. pylori contains high levels of bacterial CagA protein, which rapidly induce p53 degradation, although p53 is protected by thetumour suppressor p14ARF. The oncogenic strain 7.13 of H. pylori efficiently induces gastric dysplasia and adenocarcinoma, and this strain was significantly more potent in attenuating the expression of p14ARF and p53 compared to the non-tumourigenic strain B128. These results were confirmed in gastric epithelial cells by the ectopic expression of protein or the downregulation of ARF using shRNA [83]. The p14ARF gene promoter is frequently methylated during the development of GC, and the p53 protein is rapidly degraded as a result [84].

OTHER P53 ISOFORMS REGULATED BY H. PYLORI INFECTION
p63 and p73 are homologues of the p53 gene [85], and the high sequence similarity of their DNA-binding domain allows p63 and p73 to regulate p53-dependent cell cycle and apoptosis in response to DNA damage [86]. The P1 and P2 promoters of p63 and p73 promote the expression of a variety of protein isoforms, including the TA isoforms (TAp63 and TAp73) with an N-terminal transactivation domain (TAD) and the ΔN isoforms with diametrically opposed functions (ΔNp63 and ΔNp73) without the TAD [87,88]. Elevated levels of p73 have been reported in H. pylori-positive human and murine tissues, and in vitro assays have demonstrated the role of p73 in the pathogenesis of H. pylori infection. AGS cell lines co-cultured with H. pylori exhibited significantly increased TAp73 expression, while ΔNp63 expression was suppressed. These findings were also confirmed using dominant-negative p73 mutants [89].
∆133p53 is a truncated p53 isoform that is altered after H. pylori infection. The alternative promoter of the p53 gene, upstream of exon 1, or an internal promoter located in intron 4 results in an N-terminally truncated p53 protein initiated at codon 133 (∆133p53) [90]. Growing evidence demonstrates that ∆133p53 is overexpressed in several tumour types [91,92]. Wei et al. demonstrated that H. pylori infection induced ∆133p53 expression in AGS and SNU-1 gastric epithelial cells, and these findings were also observed in Mongolian gerbils. These cell lines were transfected with the endogenous ∆133p53 isoform shRNA plasmid, and the ∆133p53 isoforms affected the activity of p53 and p73, leading to the upregulation of the p53 target proteins p21 and phorbol-12-myristate-13-acetate-induced protein 1 (PMAIP1; also known as NOXA). Mechanistically, the activator protein-1 (AP-1) transcriptional complex, which is composed of c-Fos and c-Jun proteins, is also involved in the regulation of ∆133p53 in H. pylori cells [93,94]. This finding is consistent with previous studies showing that H. pylori accelerated the progression to gastric intraepithelial neoplasia via the upregulation of AP-1 and NF-κB activity [95]. Notably, cagPAI is required for the regulation of p53 isoforms by H. pylori.
The p53 14-3-3 protein isoform binds to the regulatory C-terminal domain of p53, and this binding is subverted in H. pylori-associated gastritis and GC [96]. The p53 14-3-3 proteins are a class of adaptor proteins with seven isoforms (β, γ, ε, η, σ, τ, and ζ) that stabilize the tumour suppressor p53 and enhance its biological activity [96]. Proteasome and immunohistochemistry analyses have demonstrated that AGS cell lines show reduced expression of 14-3-3σ and 14-3-3η [97]. In summary, these studies suggest that p53 isoforms represent novel components of the host-defence mechanism and play an important role in H. pylori-associated cell proliferation and apoptosis.

REGULATION OF THE APOPTOSIS-STIMULATING PROTEIN OF P53 (ASPP) FAMILY IN H. PYLORI-RELATED CARCINOGENESIS
The ASPP family functions as a key regulator of p53, and it consists of three members: ASPP1, ASPP2, and iASPP [98]. ASPP1 and ASPP2 enhance the ability of p53 to stimulate the expression of pro-apoptotic factors, such as Bax and p53-upregulated modulator of apoptosis (PUMA) [99]. Conversely, iASPP is a key inhibitor of p53 [100]. The apoptosis activator ASPP2 was downregulated and the apoptosis suppressor iASPP was upregulated in H. pylori-positive gastric carcinoma and pre-cancerous lesion tissues, which suggests that the ASPP family plays an important role in the gastric carcinogenesis of H. pylori infection [101].
The cancer-associated effector of the H. pylori CagA protein binds to residues 448-692 and 693-918 of ASPP2 [102]. After translocation into host epithelial cells, CagA induces the relocalization of ASPP2 rather than its abnormal expression and hinders the interaction between ASPP2 and p53, which is responsible for H. pylori-induced degradation of p53 and resistance to the apoptotic response [103,104]. Suppression of apoptosis then contributes to the development of gastric dysplasia and adenocarcinoma [105]. This finding may be in conflict with previous studies showing that H. pylori infection stimulates host gastric epithelial cell apoptosis. However, the effect of cell apoptosis may be associated with continued H. pylori colonization, and a variety of genes are known to regulate cell apoptosis. Together, these findings show that the H. pylori CagA protein interaction with ASPP2 subverts the function of ASPP2 and p53, which facilitates H. pylori-induced gastric carcinogenesis.

CONCLUSIONS
Infection with H. pylori leads to the aberrant expression of p53 protein through the induction of host DNA damage. The tumour suppressor p53 plays a major role in determining multiple signalling pathways and cellular responses. Chronic infection with the bacterial pathogen H. pylori may attenuate p53 levels via augmentation of p53 mutations, proteasome degradation and post-transcriptional modification. Furthermore, the expression of p53 transcriptional targets is inhibited and results in excessive proliferation and impaired apoptosis, which contributes to a greater risk of gastric carcinoma. Therefore, alterations of p53 may serve as a potential marker of H. pylori-associated gastric carcinogenesis.

CONFLICTS OF INTEREST
The authors declare no competing financial interests.


extfieldsofstudy: Biology Medicine

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Twelve new species and fifty-three new provincial distribution records of Aleocharinae rove beetles of Saskatchewan, Canada (Coleoptera, Staphylinidae)

Abstract One hundred twenty species of aleocharine beetles (Staphylinidae) are recognized in the province of Saskatchewan. Sixty-five new provincial records, including twelve new species and one new North American record, are presented. Oligota inflata (Mannerheim), a Palearctic species, is newly recorded for North America. The following twelve species are described as new to science: Acrotona pseudopygmaea Klimaszewski & Larson, sp. n., Agaricomorpha pulchra Klimaszewski & Larson, sp. n. (new genus record for Canadian fauna), Aleochara elisabethae Klimaszewski & Larson, sp. n., Atheta (Dimetrota) larsonae Klimaszewski & Larson, sp. n., Atheta (Microdota) pseudopittionii Klimaszewski & Larson, sp. n., Atheta (Microdota) spermathecorum Klimaszewski & Larson, sp. n., Atheta (sensu lato) richardsoni Klimaszewski & Larson, sp. n., Brachyusa saskatchewanae Klimaszewski & Larson, sp. n., Dochmonota langori Klimaszewski & Larson, sp. n., Dochmonota simulans Klimaszewski & Larson, sp. n., Dochmonota websteri Klimaszewski & Larson, sp. n., and Oxypoda domestica Klimaszewski & Larson, sp. n. Colour images of habitus and black and white images of the median lobe of the aedeagus, spermatheca, and tergite and sternite VIII are presented for all new species, Oligota inflata Mannerheim and Dochmonota rudiventris (Eppelsheim). A new synonymy is established: Tetralina filitarsus Casey, syn. n. = Tetralina helenae Casey, now placed in the genus Brachyusa Mulsant & Rey.

Introduction
Aleocharinae beetles are the most species-rich subfamily of rove beetles (Staphylinidae) with 515 species recorded in the most recent catalog of the Coleoptera of Canada ). This number is constantly increasing as new treatments of this group are published. Webster et al. (2016b) added 27 new species to the Canadian fauna from the province of New Brunswick, and Klimaszewski et al. (2015a) added two new Canadian records of species previously known from the USA, so the total number now stands at 544 species excluding the new species treated here. Aleocharinae is still one of the poorest known subfamily of rove beetles in Canada, although enormous progress has been made in investigating this group in the last two decades, especially in eastern Canada , Webster et al. 2016a. Western and northern Canada (Manitoba to British Columbia, and the three territories) , however, remain poorly studied except for a few localities in coastal British Columbia Winchester 2002, McLean et al. 2009a, b) and in the Yukon (Klimaszewski et al. 2008b. Thus the full distribution of many Canadian species is not known because of large gaps in sampling intensity ). Improved sampling of Staphylinidae, especially Aleocharinae, is needed to establish baseline biodiversity composition in areas of the country where ecosystems are undergoing rapid change due to resource extraction and climate change ). This paper contributes to improving baseline biodiversity knowledge of aleocharine beetles in the province of Saskatchewan (SK) by providing 65 new provincial species records including one new North American record and 12 species new to science.

Materials and methods
Almost all specimens in this study were dissected to examine the genital structures. Extracted genital structures were dehydrated in absolute alcohol, mounted in Canada balsam on celluloid micro-slides, and pinned with the specimen from which they originated. Images of the entire body and the genital structures were taken using an image processing system (Nikon SMZ 1500 stereoscopic microscope; Nikon Digital Camera DXM 1200F, and Adobe Photoshop software).
Morphological terminology mainly follows that used by Seevers (1978) and Klimaszewski et al. (2011). The ventral side of the median lobe of the aedeagus is considered to be the side of the bulbus containing the foramen mediale, the entrance of the ductus ejaculatorius, and the adjacent ventral side of the tubus of the median lobe with the internal sac and its structures (this part is referred to as the parameral side in some recent publications); the opposite side is referred to as the dorsal part. In the species descriptions, microsculpture refers to the surface of the upper forebody (head, pronotum and elytra).
Tribes, genera and species within genera are arranged alphabetically in the text and in the Table 1. Table 1. Species of Aleocharinae recorded from Saskatchewan and their provincial and territorial distribution within Canada. Provinces and territories in bold denote new records given in the present publication. Species marked with ( †) indicate adventive species and species marked with (*) are Holarctic.

Major habitat characterization
Almost all collections reported here were made in southwestern Saskatchewan and adjacent Alberta. This area is in the Mixed Grassland and Cypress Upland Ecoregions of the Prairies Ecozone (Ecological Stratification Working Group 1995). The Mixed Grasslands are a semiarid northern portion of the shortgrass prairie of the North American Great Plains. Summer moisture deficits promote the dominance of grasses (especially spear, blue gramma and wheat grasses) and a variety of low herbs and shrubs including sagebrush and cactus. This grassland encircles an upland area known as the Cypress Uplands. These uplands rise rather abruptly from the plains in the west to their highest elevations of almost 1500 m in SE Alberta and adjacent SK, then gradually become lower towards the east. Much of the uplands are treed with lodgepole pine, white spruce and aspen with open areas dominated by rough fescue grass and shrubby cinquefoil. The 1000 m contour was arbitrarily chosen as the boundary between these two zones for the actual boundary is complex with interdigitation of habitats such as trees and mesic plants following stream courses and valleys out into the grasslands and conversely dry grassland species occur on ridges and south-facing slopes well above the 1000 m contour. The most frequently referenced collection site is the Larson Ranch. This is located on the boundary of these two ecozones with the 1000 m contour running through the farmyard. Collections here are from a variety of habitats including: aspen or maple woodlands; fescue-cinquefoil or mixed grasslands; stream and pond margins; and on various soil types including arid tills and bedrock clays. Many ranch collections are from habitats of domestic or agricultural origin such as compost and manure piles, livestock housing or associated with exotic plants.
Other habitats within the area from which aleocharines have been collected include sand hills and saline ponds of closed drainage basins, both of which occur mainly to the north of the Cypress Hills, stream margins, and springs and fens that are common in the Cypress Hills. Considerable collecting has been done around large reservoirs. Accumulated plant material along the reservoir water lines (wrack) is often rich in beetles but windward shores (the lee shore of mariners) are often rich collecting sites as flying insects that fall into water are blown onto these shores and can sometimes be found in large numbers pulling themselves up onto the beach. Such insects are referred to as occurring in drift. Species found in wrack may in fact be in their normal habitat, but those recorded from drift are probably vagrants, but they do indicate presence and time of year of dispersal.
The low annual precipitation in the region means that a state of drought or near drought occurs frequently. Aleocharines occur mainly in moist environments, thus the majority of Mixed Grassland collections are from sites with moisture such as margins of water bodies or from moist habitats such as carrion and manure (which is very abundant due to the high populations of cattle). Carrion and manure are rich staphylinid habitat but they promote the widespread synanthropic species and a few of our new records come from these habitats. Mushrooms and other fungi, especially as they age and decay, are rich habitats but again irregularity in precipitation means that occurrence and duration of such habitats is very unpredictable over the season and from year to year. Higher levels of precipitation and lower evapotranspiration in the Cypress Uplands produce a wider and more consistent array of moist habitats and this is where we found the richest aleocharine fauna.

CNC
Canadian National Collection of Insects, Arachnids and Nematodes, Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada.

LFC
Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, R. Martineau Insectarium, Quebec City, Quebec, Canada.

Discussion
Our knowledge of the diversity and distribution of Aleocharinae in Canada has increased rapidly over the last two decades , 2015a, Webster et al. 2016a. This increase may be attributed to a surge in sampling of this subfamily and intensive taxonomic studies, as well as the increased interest in aleocharines as a target group in forestry impact studies , Pohl et al. 2007. Recently published contributions to the knowledge of aleocharine beetles in central Canada provided 33 new provincial records for the province of SK ). The present study, based on material from intensive collecting by D. Larson in southwestern SK provides 65 additional new records for the province and increased the number of known species there to 120. Of these 65 new provincial records, 12 represent species new to science, one record of an adventive species new to the province and North America (Oligota inflata), and 53 new provincial records of species known from other parts of Canada and or USA. It is interesting to note a high percentage of adventive species (16 sp., 13.3%), and a low number of Holarctic species (7 sp., 5.8%) in the SK fauna. The high percentage of adventive species is probably due to the highly modified prairie landscape that is responsible for supporting diverse habitats, and the inadequate knowledge of the total, very likely higher number of species. Agriculture has produced an environment unsuitable for many native species yet similar to European agricultural environments. Also, the sampling responsible for the species list presented here had a high bias towards habitats created in an active farm, habitats favoring synathropic species that are likely to be transported by man. The low number of Holarctic species is most likely due to poor collection in the north of the province. The Cypress Hills Upland is largely treed and contains a boreal element in its flora. However, much of its biota is derived from the western Cordillera thus contributing to the lower proportion of Holarctic species. From the 12 new species discovered, 8 represent Athetini (Acrotona -1 sp., Atheta -4 spp., Dochmonota -3 spp.), one Aleocharini (Aleochara -1 sp.), one Homalotini (Agaricochara -1 sp.), one Oxypodini (Oxypoda -1 sp.), and one Tachyusini (Brachyusa -1 sp.). While new species in poorly known groups like Acrotona, Agaricochara and some subgenera of Atheta, are expected to increase with study efforts, it was surprising to see undescribed spe-cies in well studied genera like Aleochara, Brachyusa and Oxypoda. These species are from specialized habitats that were missed in collection or were not adequately sampled previously. The most interesting discoveries are 3 new species of native Dochmonota (Athetini), a genus previously know only from western Palaearctic with one species, D. rudiventris (Eppelsheim), recorded from eastern Canada as adventive, ID and MA (Klimaszewski et al. , 2013b. Due to new distribution records , this is now considered a Holarctic species. The sampling effort by D. Larson in SK more than doubled the previously known species from the province, now standing at 122 species (Table 1).
In Canada, the Maritime provinces (NB, NS, NF, PE), and the YT are so far the best-studied regions of the country in terms of the aleocharine fauna , 2007b, 2008b, b, 2010, 2016a, b, Klimaszewski et al. 2015a). Some small areas of Quebec, Ontario, and coastal British Columbia have also received intensive sampling coupled with expert identification of material in recent years , Klimaszewski et al. 2007b.
However, the large majority of central, western and northern Canada remains poorly studied. Large numbers of aleocharines (and other staphylinids) have been collected over the last 25 years as a result of numerous trapping studies in forests, native grasslands, agricultural lands, and wetlands, especially in Alberta ). The estimated underscribed/undiscovered aleocharine species in Canada was recently discussed in Klimaszewski et al. (2015a). Bousquet et al. (2013) recorded 27 species of aleocharines from SK, while Klimaszewski et al. (2015a) estimated that some additional 227 species are awaiting discovery in SK. In this paper we recognize 120 species in SK, so at least another 100 species may be awaiting discovery. Diagnosis. Body compact, narrowly oval ( Fig. 1); head and abdomen dark brown, almost black, with pronotum, elytra and appendages orange (Fig. 1); length 3.8-4.3 mm; forebody with strong and dense meshed microsculpture; pubescence moderately dense; punctation coarser on eltra than elsewhere (Fig. 1); elytra at suture shorter than  pronotum at middle length (Fig. 1); antennomeres V-X strongly transverse (Fig. 1); mesosternum not carinate. MALE. Tergite VIII shallowly emarginate apically (Fig. 3); sternite VIII rounded apically and slightly produced medially (Fig. 4); median lobe of aedeagus with tubus arcuate ventrally and with sharp apex, internal sac with elongate structures (Fig. 2). FEMALE. Tergite VIII emarginate apically (Fig. 5); sternite VIII rounded apically and slightly produced (Fig. 6); spermatheca with C-shaped tubular capsule, and short stem (Fig. 7).

ALEOCHARINI Fleming
This species is readily distingushed from remaining Nearctic species of subgenus Echochara by its strongly transverse and orange pronotum (dark brown or black in remaining species), arcuate tubus of median lobe of aedeagus with sharp apex (Fig. 2), and C-shaped swollen capsule of spermatheca (Fig. 7), which is narrower and club-or Lshaped in other species, and by the emarginated male and female tergite VIII (Figs 3, 5).
Distribution. This species is known from the type localities in AB and SK. Natural history. The female holotype was captured on a dead ground squirrel in sand dunes. The male was collected in August from unspecified habitat. Species of subgenus Echochara are known from caves and animal burrows (Klimaszewski 1984).

Origin Nearctic Distribution
Canada: NB, NS, ON, QC, SK. USA: MI, WI New provincial records CANADA, Saskatchewan: Larson Ranch, Hwy 21, 16 km S Maple Creek, 20-X-2014, in dry polypore fungus, D. Larson (DLC) 1 female References Klimaszewski 1984 Natural history. In Saskatchewan, one female was captured in dry polypore fungus in October, and this constitutes the westernmost distribution record for this species. In NB, Aleochara inexpectata was collected from fresh moose dung in an eastern white cedar swamp and in decaying sea wrack resting on vegetation on the upper margin of a salt marsh. Adults were collected during May and June ). Collection method: sifting.

Aleochara (Calochara) rubricalis (Casey)
(for diagnosis and illustrations, see Klimaszewski et al. 1984) Distribution. Natural history. In Saskatchewan, specimens were collected from March through June, several adults were captured from carrion trap. Elsewhere, one specimen was taken from a mouse nest and other specimens were collected from February to October (Klimaszewski 1984).

Origin
Comments. We tentatively associate the SK specimen with this species because it is missing the spermatheca.

Aleochara (Coprochara) suffusa (Casey)
(for diagnosis and illustrations, see Klimaszewski et al. 1984) Distribution. References Casey 1906, Klimaszewski 1984 Natural history. In Saskatchewan, one female was captured in a carrion trap and one from wind-drift. Elsewhere, specimens were found under rocks in a high altitude meadow and some from AB were reared in laboratory (Klimaszewski 1984).

Origin
Comments. The SK specimens are darker and have only the central part of elytra reddish and the rest of the body piceous whereas the typical form of this species has the entire elytra orange or reddish-brown. Pubescence and punctation pattern and the genitalia of SK specimens are identical to the typical form with orange or reddish elytra.

Aleochara (Calochara) villosa Mannerheim
(for diagnosis and illustrations, see Klimaszewski et al. 1984) Distribution. Mannerheim 1830, Klimaszewski 1984 Natural history. In SK, 2 males were captured from a sheep barn window, and one male was found in compost. SK specimens were collected in March, April, July and September. In New Brunswick, A. villosa was collected from the nest contents of a great horned owl, Bubo virginianus (Gmelin) ). Elsewhere, specimens have been collected from carrion and sifting an old hay pile (Klimaszewski 1984). Adults were collected in May. Collection method: sifting. Etymology. The name of this species derives from the Latin participle pygmaea-, meaning small, and the prefix pseudo-, false. The genital structures of this species are similar to those of Palaearctic Acrotona pygmaea (Gravenhorst).
Distinguished from all other Acrotona by the shape of median lobe of aedeagus with apex turned dorsally in lateral view (Fig. 9), by the shape of spermatheca with thin, long, sinuate, and posteriorly looped stem (Fig. 15), and by the shape of tergite and sternite VIII, which have basal margin straight and not sinuate (Figs 11-14).
Distribution. This species is known only from the type locality in SK. Natural history. The type specimens were sifted from old mouldy alfalfa hay. Comments. This species is similar to Palaearctic A. pygmaea (Gravenhorst) from which it differs by subquadrate antennal articles VI-X, by apex of tubus of median lobe of aedeagus more angular, female sternite VIII emarginated apically and spermatheca with much longer and broadly looped stem. It is also genitally similar to Nearctic Acrotona actuella (Casey) and A. egregiella (Casey), from which it differs by straight and not sinuate ventral margin of tubus of median lobe of aedeagus, by straight and not sinuate basal margin of male tergite VIII, and by differently shaped spermatheca with posterior loop of stem sinuate.  Majka and Klimaszewski 2010, Webster et al. 2016b Natural history. In SK, one female was captured from maple (Acer negundo) litter and one from willow (Salix spp.) leaf litter in June and October, respectively. In NB, Acrotona subpygmaea was found in litter of a variety of forest types and in wetlands including swamps, sphagnum bog, marshes and river margins. Specimens have also been taken from gilled mushroom and under bark . Most adults were collected in May, with a few in April, June, August, and September.

Amischa analis (Gravenhorst)
(for diagnosis and illustrations, see Klimaszewski et al. 2011) Distribution. Origin Palaearctic Natural history. In SK, one female was captured in October by sifting leaf litter along a creek. In NL, adults were collected in pitfall traps in agricultural fields, an urban field and on coastal sand dunes amidst vegetation, and the activity period was June to September . Elsewhere, adults in general occur in organic litter. Natural history. In SK, two males were found in compost in September, one female in wrack on lakeshore in July, and one female from unknown habitat in August. In NF, adults were collected from May to August in carrion-baited pitfall traps and flight intercept traps in conifer-dominated and mixedwood forests, and on the coastal barrens of southeastern LB . In NB, adults were collected in September from red spruce forest .

Atheta (Dimetrota) districta Casey
(for diagnosis and illustrations, see Klimaszewski et al. 2011) Distribution. References , Majka and Klimaszewski 2008 Natural history. In SK, one male was captured from dry and decaying mushroom, and another from spruce litter in September. In NF, adults were collected from June to August in carrion-baited pitfall traps and flight intercept traps in conifer-dominated and mixedwood forests, and on coastal barrens . In NB, adults were collected in June through September in red spruce forest .  Klimaszewski et al. 2008b Natural history. In SK, specimens were collected from decaying mushrooms, bracket/gilled fungi, in spruce-aspen and aspen woodland forests. In YT adults were captured in June, July, and August at an elevation of 772 m in a white spruce and mixed white spruce-lodgepole pine forests (Klimaszewski et al. 2008b). Etymology. The name of this species is dedicated to R.I. Larson. Ruby I. Larson was a geneticist at the Agriculture Canada Research Station, Lethbridge, who worked on wheat genetics. She was very active in promoting science and from 1958 to 1973 ran a Science Club for Junior High and High School age children. Members of this club went on to a variety of professional careers, including three (DJL included) who became professional entomologists. Her love of learning and science was infectious and her support and encouragement were major factors in our career choices. She taught us the joy and personal rewards of following one's curiosity.

Unknown.
Distinguished from all other Atheta (Dimetrota) by narrow head and pronotum, broad and short elytra, strongly glossy integument, and the shape of median lobe of aedeagus with apex produced ventrally in lateral view (Fig. 17).
Distribution. This species is known only from the type locality in SK. Natural history. The holotype was captured in June from unspecified habitat.
Comments. This species is superficially similar to Nearctic Atheta (D.) peticapensis Klimaszewski & Webster, with which it shares similar body proportions and enlarged bulbus of median lobe of aedeagus. However, these differences may not necessarily indicate a close relationship between these species. Casey 2010, Klimaszewski et al. 2005, 2008a, b, 2011 Natural history. In SK, several females were found in dry and decaying mushrooms in August. In NF, adults were collected from June to October in carrion-baited and unbaited pitfall traps and in flight intercept traps in many forest types (coniferous, mixedwood and deciduous), and some adults were found in rotting mushrooms in forests . Elsewhere, adults were collected in June and August, from organic litter in red spruce forest in NB and forest litter in YT (Klimaszewski et al. , 2008b. References Klimaszewski et al. 2011, Webster et al. 2012 Natural history. This species is frequently associated with forest mushrooms. In SK, specimens were captured from an old polypore fungus on dead lodgepole pine stump, and in spruce-aspen forest, in August and September. In NF, adults were collected from June to August in carrion-baited and unbaited pitfall traps and in flight intercept traps in many forest types (coniferous, mixedwood and deciduous), and some adults were found in rotting mushrooms in forests . In YT, specimens were found in mushrooms, in birch and mixed pine and willow forests, and white spruce and feathermoss forest in July and August ). Most specimens from NB were collected from fresh and decaying gilled mushrooms. One individual was collected from a rotting lobster mushroom and another from a coral mushroom on a spruce log . This species was found in mixed forests, mature red spruce forests with red maple or birch, a black spruce forest, an eastern white cedar swamp, and a red oak forest . Adults from New Brunswick were collected during August, September (most specimens), and October . Etymology. The species name pseudopittionii derived from the prefix pseudo-(false) and the specific name of European species Atheta pittionii Scheerpeltz, to which it is similar externally and has similar genitalia.

Atheta
Diagnosis. Body narrowly subparallel (Fig. 21), length 1.9-2.0 mm, uniformly black with tarsi yellowish; head, pronotum and elytra finely and sparsely punctate and pubescent, punctures small; integument strongly glossy, more so on abdomen, with meshed microsculpture; pronotum transverse, distinctly narrower than elytra, with pubescence directed obliquely anteriad anteriorly and obliquely posteriad posteriorly from median line of disc (Fig. 21); elytra at suture distinctly longer than pronotum ( This species is very similar to European A. pittionii Scheerpeltz, from which it differs by broader and more elongate elytra, larger bulbus of median lobe of aedeagus in dorsal view (Fig. 23), more sinuate base of tubus of median lobe of aedeagus in lateral view (Fig. 22), and differently shaped complex structures of the internal sac (Figs 22,23). For genitalia of A. pittionii, see Brundin (1948) [under the name of A. parvicornis].
Distribution. Adults are known only from SK. Natural history. Most adults of this species were collected from Shaggy parasol mushrooms, Chlorophyllum rhacodes (=Lepiota rhacodes), from unspecified mushrooms, and from carrion.  Klimaszewski et al. 2012 Natural history. One SK male was captured in bracket/gilled fungi in aspen woodland in June, and the other from spruce-aspen woodland in September. In YT, two males were captured by sifting litter in mixed aspen and white spruce forest in September, and one female was found on a mushroom in August . Etymology. The species name spermathecorum is derived from the name of spermatheca in reference to unusually shaped capsule of the spermatheca of this species.
It is distinguished from all other Nearctic species of Atheta, subgenus Microdota, by the unique shape of spermatheca bearing bulbus apical projection on top of capsule (Fig. 32).
Distribution. Adults are known from SK and AB. Natural history. Females were captured in March (Alberta), May and July (Saskatchewan): one was found in a decaying polypore mushroom and one was found in lake drift in May.

Atheta (Rhagocneme) subsinuata Erichson
(for details and body image, see Klimaszewski et al. 2008b) Distribution.  Klimaszewski et al. 2008b Natural history. Like many introduced species, A. subsinuata appears to be synanthropic, as all collections have been made from artificial habitats. The Saskatchewan specimens were sifted from old mouldy alfalfa hay in June and July, and one female was taken in September from compost. In YT, four specimens were captured in a compost pile in September 2005 (Klimaszewski et al. 2008b).
Natural history. The SK female was captured in decaying mushrooms in September. In LB, adults were abundant in pitfall traps during July and August in an open spruce forest with sandy soil and Cladina lichen cover, and a few adults were captured using pitfall traps in a birch-dominated forest . Elsewhere, adults occurred from July to October in organic debris in red spruce forest, in polypore fungus in coniferous forest, and on the forest floor in red oak and deciduous forests , Majka and Klimaszewski 2008.

Incertae sedis
The following species have uncertain subgeneric affiliation in the large and diverse genus Atheta. Some of the species belong to a group of species described in Europe by Benick and Lohse (1974) as the "Mischgruppe" (mixed group) of Atheta.

References
Casey 1910, Klimaszewski et al. 2005, 2007b, Majka and Klimaszewski 2008 Natural history. The SK specimens were captured from aspen/pine litter and pine/ spruce litter in August through October. In NB, most adults of A. pseudoschistoglossa were found in or near wetland habitats including among cobblestones, drift material, and flood debris along river margins, moist leaves along vernal pond margin in a silver maple swamp, in leaf litter and moss along brook margins in alder swamps, and in litter at base of red maple, in Carex hummock in Carex marshes, in leaf litter in a red oak forest near seasonally flooded marsh, in a salt marsh, in marsh litter in a Carexsedge marsh, and in litter and sphagnum at the base of a tree in a marsh . A few adults were captured in Lindgren funnel traps in hardwood woodland near a seasonally flooded marsh and in an old mixed forest ). Adults were collected from mid-April to August .
Natural history. In SK one female was captured from dry and decaying mushrooms. In NL, adults were collected from June to September using unbaited and carrion-baited pitfall traps and flight intercept traps in many forest types (deciduous, mixedwood, coniferous, riparian), and also in rotting mushrooms in forests . Elsewhere, adults were collected in NB from red spruce mixed forest from June through September , and in QC from yellow birch/balsam fir dominated forest in June and July (Klimaszewski et al. 2007b). Etymology. This species name is derived from the surname of Sir John Richardson, the surgeon-naturalist who participated in 19th century British naval expeditions to the arctic coast of "British North America", now Canada. In 1820 he discovered a new species of ground squirrel along the Saskatchewan River, which was later named after him as Urocitellus richardsonii. The holotype of Atheta richardsoni was found in a Richardson's ground squirrel burrow.
Distinguished from all other species of Nearctic Atheta by its small size, densely and finally punctate and pubescent forebody, nearly all pronotal pubescence directed straight posteriad (Fig. 33), the shape of median lobe of aedeagus with very broad tubus of median lobe in dorsal view (Fig. 35), and the shape of spermatheca with enlarged, sac-shaped posterior part of stem (Fig. 40).
Distribution. Adults are known from SK. Natural history. The single male from SK was captured in a ground squirrel burrow, and the single female was found in a Prairie Dog colony in June.
Comments. This species in body size and general appearance is similar to species of the subgenus Microdota of Atheta. However, it has a different pubescence pattern of pronotum with microsetae along midline of disc directed straight posteriad and elsewhere straight or obliquely posteriad (Fig. 33), and pubescence on elytra with microsetae directed approximately straight posteriad (Fig. 33). The tubus of the median lobe of the aedeagus is very broad and abruptly narrowed apically in dorsal view (Fig. 34), and spermatheca has enlarged and sac-shaped posterior part of stem (Fig. 40). These are unique features of this species, which slightly resemble those of European Atheta liturata Stephens, which has a similarly shaped median lobe of aedeagus and spermatheca, but the European species has a differently shaped male tergite VIII with strong lateral projections (for illustrations, see Palm 1970). The European species is known from mushrooms. Benick and Lohse (1974) assigned A. liturata to Atheta (Mischgruppe III, IV).

Origin
Palaearctic Natural history. The SK specimens were captured in May and June from unspecified habitat. Elsewhere, this species is associated with soil and organic debris in agricultural fields and disturbed urban meadows. It is also found in marsh litter, in leaf litter in mixed forests, in compost, under bark of decaying spruce logs, amongst vegetation on a coastal sand dune, in litter in a cattail marsh, in leaf litter along a vernal pond, and in drift material along a lakeshore . The adult activity period is April to September.

Dinaraea pacei Klimaszewski & Langor
(for details and illustrations, see Klimaszewski et al. 2011Klimaszewski et al. , 2013a Distribution. Natural history. The SK specimens were captured from aspen woodland bracket/ gilled fungi, and from under aspen bark. Adults in NF and LB were collected from June to August using pitfall traps and flight intercept traps in various coniferous forest types, and one specimen was collected under the bark of a dead red pine . In BC, adults were caught in July and September in emergence traps attached to the trunks of lodgepole pine (Pinus contorta Dougl. ex Loud. latifolia Engelm.) infested by mountain pine beetle (Dendroctonus ponderosae Hopkins) ). In NB, adults were found: under the bark of large fallen spruce in an old-growth eastern white cedar swamp; under tight bark of American elm; in a silver maple forest; in fleshy polypore fungi at the base of a dead standing Populus sp. in a wet alder swamp; and in a group of Pholiota sp. at the base of a dead Populus sp. in a mixed forest. In Quebec, adults were found in dead black spruce in a black spruce forest ). Adults were also captured in Lindgren funnel traps deployed in an old-growth white spruce (Picea glauca (Moench) Voss) and balsam fir forest, an old mixed forest with red and white spruce, red and white pine (Pinus strobus L.), and a rich Appalachian hardwood forest with some conifers ). Adults were collected from March to September ).

Key to Nearctic species of Dochmonota
Diagnosis. Body narrowly subparallel (Fig. 49), length 2.2-2.5 mm, uniformly black; head, pronotum and elytra finely and densely punctate, punctures small; pubescence dense; integument moderately glossy, more so on abdomen, with meshed microsculpture (Fig. 49); antenna with articles V-X subquadrate to slightly transverse (Fig. 49); head about as wide as pronotum (Fig. 49); pronotum transverse, slightly narrower than elytra at base, with pubescence directed obliquely laterad from median line of disc and in basal part of median line directed anteriad and laterad, base of disc with small oval impression (Fig. 49); elytra at suture about as long as pronotum and slightly wider at base than pronotum (Fig. 49); abdomen subparallel. MALE. Tergite VIII truncate apically (Fig. 52); sternite VIII elongate and notched apically (Fig. 53). Median lobe of aedeagus with large broad bulbus and narrow triangular tubus in dorsal view, bulbus strongly sinuate laterally (Fig. 51), in lateral view tubus straight and slightly sinuate basally; crista apicalis of bulbus small (Fig. 50); internal sac structures as illustrated (Figs 50, 51). FEMALE. Tergite VIII truncate apically (Fig. 54); sternite VIII arcuate apically (Fig. 55); spermatheca with pitcher-shaped capsule bearing broad and deep apical invagination, stem broad, and coiled (Fig. 56). Distribution. This species is known only from SK. Natural history. Adults of this species were collected by sifting wrack on lakeshore beach, and were found in wind-drift on a lake. Etymology. The species name is derived from Latin adjective simulans-, meaning imitating, in reference to its similarity to the closely related Dochmonota websteri.
Distribution. Adults are known only from SK. Natural history. The male of this species was captured in June in unspecified habitat, and one female was taken from saline slough, also in June. Etymology. The species is named for Dr. Reginald R. Webster, close friend of JK, and extraordinary entomologist who "understands aleocharine beetles" and who   changed the beetle map of New Brunswick by endless discovery of new species. In memory of our "grappa discussions" and fruitful collaboration.
Distribution. Adults are known only from SK. Natural history. Most adults of this species were collected from shorelines of eutrophic lakes in June, August and September, and one male was captured in organic mud/sedges, and rushes near water.
Comments. A male from Bigstick Lake had slightly distorted median lobe of aedeagus and was excluded from the type series. References Gusarov 2002, 2007b, 2008a, Majka and Klimaszewski 2008 Natural history. The SK females were captured in June from unspecified habitat. In NL, adults were captured from June to September in the litter of a riparian forest and along the shore of a pond . Elsewhere, adults were captured in leaf litter near the margin of a brook in a red maple swamp, in mixed forests of different ages, in river debris, gopher burrows, and under decaying seaweed on a seashore , Majka and Klimaszewski 2008). Adult activity occurs from April to September.

Mocyta breviuscula (Mäklin)
(for details and illustrations, see Klimaszewski et al. 2015a, b) Distribution. References Lohse et al. 1990, 2007b, 2008a, b, 2015a, b, Bousquet et al. 2013 Natural history. The SK specimens were captured by sifting aspen litter, maple litter, aspen choke-cherry leaf litter, willow and aspen litter, hawthorn litter near creek, willow leaf litter, under fresh-cut aspen log rings, from decaying woodland bracket/ gilled fungi, and from compost, in May through October. In Newfoundland, adults were frequently caught in pitfall traps in various forest types (birch, spruce-lichen, spruce-poplar, fir), in vegetation on coastal sand dunes, on shrubby limestone barrens and in disturbed fields amongst grass and weeds . The activity period is June to September. Adults were captured with pitfall traps from June to August in moss and leaf litter in red spruce forest in New Brusnwick and yellow birch/ balsam fir forests in southern Quebec (Klimaszewski et al. 2005b(Klimaszewski et al. , 2007b(Klimaszewski et al. , 2015b.

Mocyta sphagnorum Klimaszewski & Webster
(for details and illustrations, see Klimaszewski et al. 2015b) Distribution.  Klimaszewski et al. 2015b Natural history. In SK, specimens were captured from May through September from willow-aspen litter, hawthorn litter near creek, wet grass and weed clippings, moist spruce litter near stream, spruce litter, spruce-aspen litter, and in decaying mushrooms. In NB, adults were found in sphagnum moss and litter in calcareous eastern white cedar fens and in a black spruce forest (Klimaszewski et al. 2015b). One individual was collected from mouldy conifer duff at the base of a large pine in a mixed forest (Klimaszewski et al. 2015b). Adults were found in April and May in New Brunswick, and June to August elsewhere. This species often seems to be associated with moist sphagnum moss (Klimaszewski et al. 2015b).

Origin
Comments. Males of this species can be mixed up with those of M. breviuscula and positive identification may only be possible with female association as Mocyta are definitively identified by the shape of the spermatheca.

Nehemitropia lividipennis (Mannerheim)
(for details and illustrations, see Klimaszewski et al. 2007aKlimaszewski et al. , 2011 Distribution. Origin Palaearctic, adventive in Canada References  Natural history. The SK specimens were captured from an unspecified habitat in September. In NL, one specimen was collected in October from an unspecified habitat . Elsewhere in North America, adults were captured in open fields and pastures, in organic debris including dead grass, in caribou, horse and cow dung, in open marsh, maple/beech forest, the edge of an oak forest, and in the nest of Microtus pennsylvanicus (Ord) .

Origin Nearctic Distribution
Canada: MB, SK New provincial records CANADA, Saskatchewan: Cypress Hills Park, Highland Trail, 10-VI-2013, treading quaking moss, Typha, Equisetum, D. Larson (DLC) 1 male. References Lohse et al. 1990 Natural history. The SK male was captured in June by treading quaking moss, Typha, and Equisetum. The MB specimens were captured in June and August, from unspecified habitat ).

Philhygra subpolaris (Fenyes)
(for diagnosis and illustrations, see Fenyes 1909, Klimaszewski et al. 2016 Distribution.  Fenyes 1909, Klimaszewski et al. 2016 Natural history. In SK, one male was captured in May by sifting willow/grass litter, and one female was sifted from wrack on a lakeshore in June. In AB, adults were caught in window traps attached to aspen snags in a boreal aspen stand harvested 2 years previously, and in pitfall traps deployed in canola fields. Adults were collected in July (Klimaszewski et al. 2016a).

Strigota ambigua (Erichson)
(for diagnosis and illustrations, see Klimaszewski et al. 2011) Distribution. Natural history. In SK, one specimen was found in Scirpus wrack on the shore of saline pond, and three others were found in unspecified habitats in May, July and September. In NB, one specimen was found under a cobblestone on moist sand on a lake margin ). This widespread species occurs in open habitats, including dunes, beaches, limestone barrens, soybean fields, old fields, open gaps in spruce forest, riverbanks and groundhog burrows ).

Origin Nearctic Distribution
Canada: NB, ON, SK New provincial records CANADA, Saskatchewan: Cypress Lake, E dam, wind-drift, 9-V-2012, D. Larson (DLC) 1 female. References Brunke et al. 2012 Natural history. In SK, one female was captured in May from wind-drift on the lake. In NB, S. obscurata was found in flood debris on a river mar gin, on soil at the base of grass in a residential lawn, and captured in a Lindgren funnel trap in an old jack pine forest ). Brunke et al. (2012) reported this as the most common species in southern Ontario soybean fields, often occurring in open habitats with S. ambigua.

Autalia rivularis (Gravenhorst)
(for diagnosis and illustrations, see Klimaszewski et al. 2011) Distribution. Origin Palaearctic Natural history. The SK specimens were found in moose dung, under bark of dead aspen, and in compost in June, August and September. In NL, adults were collected in July using flight intercept traps in mixedwood forest and carrion traps on coastal shrubby barrens . Elsewhere, adults were collected in July and August from red spruce dominated regenerating forest in NB . In Europe, this species is very common in cow dung and rotting organic debris.

Falagria caesa Erichson
(for diagnosis and illustrations, see Klimaszewski et al. 2013b, Hoebeke 1985 (Paykull)]) Natural history. The SK specimens were found in compost, wind drift, and beach wrack, from June through September. In North America, this species is associated with decaying plant material such as compost, mouldy corncobs, cornhusks, weeds, haystacks and rotting fungi (Hoebeke 1985.

Origin
Comments. This species is well established in northeastern and western North America (Hoebeke 1985). It was listed in North America as F. sulcata (Hoebeke 1985, Campbell and Davies 1991. The oldest record of this adventive species in SK is that of 1976.

Myrmecocephalus arizonicus (Casey)
(for diagnosis and illustrations, see Hoebeke 1985) Distribution.  Hoebeke 1985 Natural history. The SK specimens were found in pine clearcut, on recently dead white spruce, and in moss and pine litter in May, June and September. Elsewhere, specimens were collected from under bark of logs, from leaf litter, flood debris and wet moss, from soil along a stream, from fungus (Fomitopsis pinicola, Fomes robineae), and from a squirrel midden (Hoebeke 1985). Etymology. A Latin feminine adjective pulchra, meaning beautiful, in reference to the body shape and beautiful colour of this species.
Distribution. Known only from SK. This constitutes new genus record for Canadian fauna.
Natural history. Adults were collected from mouldy aspen logs in September and by sifting aspen litter in July.
Comments. Seevers (1951) considered Agaricochara Kraatz as a subgenus of Gyrophaena Mannerheim, but Ashe (1984) elevated it to the generic rank. We have followed Ashe (1984) in treating this taxon as a genus. There are two species of Agaricochara in Europe and six in North America (Seevers 1951). No member of either group of species matches our new species from SK, which has very distinctively shaped tubus of the median lobe of the aedeagus with ventral process-like projection angularly bent subapically and directed dorsally (Fig. 74).

Gyrophaena lobata Casey
(for diagnosis and illustrations, see Seevers 1951 Distribution. References Casey 1906, Seevers 1951 Natural history. The SK specimen was collected in August from unspecified habitat. In NB, adults were captured in gilled mushrooms in mixed and hardwood forests from July through September by sifting mushrooms and aspirating specimens ).

Gyrophaena subnitens Casey
(for diagnosis and illustrations, see Seevers 1951 Distribution. References Casey 1906, Seevers 1951 Natural history. Two SK specimens were found in aspen woodland on bracket/ gilled fungi, in June and July. In NB, specimens were collected by sifting in June from sun-exposed gilled mushrooms on stump in 8.5-year-old regenerating mixed forest and red oak ).

Leptusa gatineauensis Klimaszewski & Pelletier
(for diagnosis and illustrations, see Klimaszewski et al. 2004) Distribution.  Klimaszewski et al. 2004, McLean et al. 2009a, b, Bousquet et al. 2013 Natural history. The SK specimens were collected from willow, aspen, and hawthorn litter near creek, under bark of dead aspen, in polypore fungus on aspen, in May and June. Elsewhere, two specimens were captured in May on Polyporus betulinus, one by general sweeping in deciduous forest, and one in June in red spruce/hemlock mature forest (Klimaszewski et al. 2004). A few specimens were collected by funnel trap in Stanley Park, Vancouver (McLean et al. 2009a, b).

Origin Nearctic Distribution
Canada: AB, BC, SK New provincial records CANADA, Saskatchewan: Cypress Hills Park, Center Block, Lodgepole Trail, 24-IX-2014, decaying mushrooms, D. Larson (DLC) 1 male. References Klimaszewski et al. 2008b Natural history. The SK male was found in September in decaying mushrooms.

Cypha inexpectata Klimaszewski & Godin
(for illustrations, see Klimaszewski et al. 2008b) Distribution.  Klimaszewski et al. 2008b Natural history. In SK, specimens were collected from mossy hummocks at the border between a marsh and spruce forest, and mossy hummocks near creek, in September and October.
Distribution. References Mannerheim 1830, Williams 1978 Natural history. The SK specimens were found in compost and new brome/alfalfa hay. Collecting period: June, August and September Comments. Oligota inflata is a Palaearctic species known from Europe, N. Africa, Congo, Egypt, and Brazil. It is reported here for the first time from North America.

Tribe LOMECHUSINI Fleming
Zyras obliquus (Casey) (for illustrations, see Klimaszewski et al. 2011) Distribution. Natural history. In SK, one specimen was collected in May from lodgepole pine litter. Elsewhere, adults were captured in clear-cut Sitka spruce forest on Vancouver Island and in moss and gravel at the edge of small pools at other localities in the interior of British Columbia . Additional specimens were found in British Columbia in a 1-year-old harvested Douglas-fir stand. In westcentral Alberta, adults were collected in pitfall traps deployed in Upper Cordilleran coniferous forests, including subxeric lodgepole pine forests, mesic white spruce and lodgepole pine stands and spruce-dominated subhygric and hygric forests, but not in deciduous-dominated forest or in grassy or shrubby meadows . In Alberta, adults also emerged from lodgepole pine trees infested by bark beetles ). In the Yukon Territory, adults were found in a squirrel midden in spring, probably overwintering, and in a coniferous woodchip pile .

Hylota ochracea Casey
(for illustrations, see Klimaszewski et al. 2006) Distribution. Natural history. In SK, one specimen was collected from pigeon coop, one from carrion trap, and one from unspecified habitat. In NB, Hylota ochracea was a common inhabitant of barred owl nests ). Barred owl nests were in tree holes (usually in large trees) and in artificial nest boxes ). Adults of H. ochracea occurred in the nest contents, which usually consisted of rich decaying organic material with bones, fur, owl pellets, portions of dead prey items (mice, squirrels, small birds), and often the contents had a strong urine smell. This species was also found in the nest contents of the great horned owl. Majka et al. (2006) reported this species from the nests of the boreal owl, Aegolius funereus richardsoni (Bonaparte) and northern saw-whet owl, Aegolius acadicus (Gmelin) in Nova Scotia. Interestingly, H. ochracea was also common among decaying vegetables inside a plastic compost bin, which in some respects mimics the conditions found within a tree hole occupied by an owl ). Only one adult of H. ochracea has been captured in New Brunswick in a habitat other than a tree hole or other enclosed situation; in drift material along a river margin ). Adults were collected in May, June, August and September.

Oxypoda demissa Casey
(for illustrations, see Klimaszewski et al. 2006Klimaszewski et al. , 2011 Distribution. Natural history. In SK, specimens were captured in willow, aspen, and hawthorn litter near creek, and under bark. In New Brunswick, adults were captured in moist leaf litter on the margin of a vernal pond in a mixed forest, among leaves and sedges on pond margin, in moist grass litter and sphagnum in Carex marsh, among sedges along margin of small spring-fed brook in a mature hardwood forest and among leaf litter and grass on hummocks in a wet alder (Alnus sp.) swamp ). In Nova Scotia, this species was reported from litter of Alnus clumps . A number of adults were collected with a net during late afternoon (15:00 to 18:00 h) flights ). Adults were captured from April to July, and in October. Collection method: sifting leaf litter, some collected in flight with net during evening. Etymology. The name of this species is derived from Latin feminine adjective domestica-, meaning domestic, in reference to the capture of the type specimens in the vicinity of the farmstead.
Natural history. The two males were captured in April in an unspecified habitat near a farmstead.
Comments. This species is very similar externaly to O. irrasa Mäklin, from which it may be distinguished by the shape of tubus of median lobe of aedeagus with slightly sinuate ventral margin and triangular apical part in lateral view (Fig. 85). In O. irrasa, tubus of median lobe of aedeagus is angularly bent ventrally and apical part is evenly narrowly elongate. For illustrations of O. irrasa, see Klimaszewski et al. (2006).

Oxypoda irrasa Mäklin
(for illustrations, see Klimaszewski et al. 2006) Distribution. Natural history. In SK, specimens were captured on decaying and old polypore mushrooms in lodgepole pine and spruce-aspen habitats in March, July, August and September. One specimen was captured on snowbank in March. Elsewhere, adults were captured from May through August with most of the specimens taken in August . At the EMEND site (Alberta), adults of Oxypoda irrasa (n = 519), like those of O. grandipennis, were found in all cover types and all retention treatments but were most abundant in unharvested stands . Oxypoda irrasa was collected from May through August at EMEND (Alberta), however a few individuals were collected in May through July ). This species was most abundant in August. Collecting methods: unbaited pitfall traps, sifting forest litter and processing it through Berlese funnels.

Oxypoda manitobae Casey
(for illustrations, see Klimaszewski et al. 2006) Distribution.   Natural history. In SK, specimens were captured in June and August, one male was found in flood debris along the margin of a seasonal creek. Elsewhere, adults were captured in July and August in Arctic habitats or in the Rocky Mountains (853-2896 m) (Klimaszewki et al. 2006).

Parocyusa fuliginosa (Casey)
(for illustrations, see Klimaszewski et al. 2011 Distribution. Natural history. In SK, specimens were captured in pine/spruce litter near stream, under fresh-cut pine slabs, and under bark of recently killed aspen. In AB, adults were collected from dead or dying white spruce in aggregated retention patches surrounded by different levels of dispersed retention, using emergence traps and window traps . Elsewhere, adults were found in various deciduous and coniferous forests, using a pit-light trap and ethanol-baited Lindgren funnel traps . The adults in northwestern Alberta were collected from June to September .

Origin
Natural history. In SK, one male was captured under bark of recently killed aspen. In AB, adults were reared from white spruce logs in early and intermediate decay stages in white spruce dominated stands . Elsewhere, adults were found in various deciduous and coniferous forests, using a flight intercept trap, ethanol-baited Lindgren funnel traps, pit-light traps, and pitfall traps .

Placusa tacomae Casey
(for diagnosis and illustrations, see Klimaszewski et al. 2001) Distribution. Natural history. In SK, adults were captured from mouldy aspen log, newly cut lodgepole pine log, and in Ips tunnels in lodgepole pine. In eastern Canada, P. tacomae was collected in Lindgren funnel traps from Pinus strobus, Pinus resinosa, Pinus banksiana, Picea glauca, and A. saccharum stands ). In western Canada, a single individual of this species was recovered from an alpha-pinene-baited Lindgren trap at 850 m elevation in the coastal montane forest near Campbell River on Vancouver Island ). One specimen from Colorado was taken at an elevation of 9600 ft (1 ft = 0.3048 m) from Picea engelmannii forest . Western host tree forest: Pinus monticola, mature T. heterophylla -A. amabilis, Pinus contorta . Collection period: May-August and October in British Columbia. Scolytid host: Dendroctonus ponderosae (Alberta); Ips pini (British Columbia) ).

Placusa vaga Casey
(for diagnosis and illustrations, see Klimaszewski et al. 2001) Distribution. Casey 1911,  Natural history. In SK, one specimen was captured under bark of lodgepole pine. In QC, specimens were captured in Abies balsamea stands: old-growth stands, undetermined age stands, in Picea glauca stand, and Populus tremuloides with Picea glauca stand . All Quebec specimens except one (Multi-Pher 7 pitfall trap) were captured in Lindgren funnel traps baited with alpha-pinene and 95% ethanol, and with 70% ethanol as preservative . Collecting period: June to August.

Silusa californica Bernhauer
(for diagnosis and illustrations, see Klimaszewski et al. 2003Klimaszewski et al. , 2011 Distribution. Natural history. In SK, adults were captured from gilled mushrooms, dry and decaying mushrooms, old polypore fungus on dead lodgepole pine stump and on lodgepole pine. Elsewhere, adults of S. californica were collected from July through September by means of passive pitfall traps, Luminoc pit-light traps, Malaise traps and by sifting forest litter, wet moss on forest floor, marten dung on moss, and mushrooms . Most specimens were captured in the passive pitfall traps. Adults occurred in coniferous (red spruce, Sitka spruce), mixed-wood (yellow birch/ balsam fir), and unspecified deciduous forests . The Alberta specimens were collected in boreal mixed-wood forest, predominantly trembling aspen with a small amount of eastern balsam poplar, white birch, white spruce, and willow species . Five of the specimens were taken from old stands at least 100 years of age, nine were from mature stands 65 to 75 years of age, and three were from a recently harvested stand, 3 years of age . The specimens from the Carmanah Valley, Vancouver Island, British Columbia, were mainly captured in the forest interior, followed by fewer in the transition zone, and only two specimens were found in the clear-cut zone . Natural history. In SK, one specimen was captured in pine/spruce litter near stream, and another in an unspecified habitat in August and September. In LB, adults were collected in July and August on sand and gravel on the banks of the Churchill River . Elsewhere, adults were collected near lake and river shorelines, on clay, sand and gravel beaches and sandy and silty river margins . The adult activity period is May to August.

Brachyusa
Comments. The two SK females agree in colour, body shape, morphology of tergite and sternite VIII, and spermatheca with the type of B. helenae and the recently examined specimens from NF and NB. We have studied the types of B. alutacea (Casey), B. filitarsis (Casey) and B. helenae (Casey). The genital illustrations of B. americana (Fenyes), recorded from BC, are provided by Seevers (1978). We have not found any significant morphological differences between the types of B. filitarsis and B. helenae, and the two species are synonymous. However, B. alutacea clearly differs from B. helenae/filitarsis by a very broad body. Seevers' (1978) key to species based on antennae and the length of the basal article of the metatarsus is not accurate. Etymology. The name of this species, saskatchewanae-, is a feminine adjective derived from the name of the province of Saskatchewan, where the type series was found.
Brachyusa saskatchewanae may be distinguished from other Brachyusa species by its uniformly black and narrow body, sinuate lateral margins of pronotum, and the genitalic features described above (Figs 99, 100, 105).
Distribution. Known only from SK. Natural history. All SK specimens were captured near water with some on sandyclay river bank. They were mainly collected by splashing water onto the bank, which caused the beetles to run up the bank.

Origin Nearctic Distribution
Canada: NB, SK New provincial records CANADA, Saskatchewan, Cypress Hills Park, West Block, 5 km E AB border, 30-VI-2012, sandy-clay river bank, D. Larson (DLC) 1 female. References Klimaszewski et al. 2008c Natural history. In SK, one female was captured in June from sandy-clay river bank. In NB, two specimens were captured in June, one from under debris on muddy soil near a small pool in a silver maple forest, and the other from under debris on clay and sand mix at river margin (Klimaszewski et al. 2008c)

Origin Nearctic Distribution
Canada: NB, SK New provincial records