Contributions towards an understanding of the Atomariinae ( Coleoptera , Cryptophagidae ) of Atlantic Canada

Th e Atomariinae (Coleoptera: Cryptophagidae) fauna of Atlantic Canada are surveyed. Ten species in the genus Atomaria are reported in the region, six of which, including Atomaria distincta Casey, Atomaria fuscata Schönherr, Atomaria lederi Johnson, Atomaria lewisi Reitter, Atomaria testacea Stephens, and Atomaria nigrirostris Stephens, are newly recorded in Canada. Atomaria lederi and A. lewisi are newly recorded in North America. Twenty-three new provincial records are reported. Atomaria curtula Casey, 1900 (syn. n.) is designated as a synonym of Atomaria lewisi Reitter; Atomaria ovalis Casey, 1900 (syn. n.) is designated as a synonym of Atomaria apicalis Erichson, 1846; and Atomaria saginata Casey, 1900 (syn. n.) is designated as a synonym of Atomaria fuscata Schönherr. A key to species is provided, as are species descriptions. Records of all species are given and their distribution in the region is plotted. Th e global distribution of all Holarctic and adventive species is briefl y summarized, and the jurisdictions in North America where they have been reported are compiled. Habitat and bionomic information is also provided for all species, both from within the region, and from observations in European studies. Th e fauna is briefl y discussed from a zoogeographic perspective; two species are Nearctic in origin, fi ve may be Holarctic in distribution, and three others may be adventive Palaearctic species, although further evidence is required to confi rm such preliminary assessments. Similarly, because of the paucity of information on this genus, further fi eldwork is required to fully discern the distribution of these species in Atlantic Canada. Th ree are apparently saproxylic species characteristic of forested habitats; three are primarily grassland species; and the remaining four are eurytopic species found in a wide variety of forested and open habitats. ZooKeys 35: 37–63 (2010) doi: 10.3897/zookeys.35.318 www.pensoftonline.net/zookeys Copyright C.G. Majka, C. Johnson, D.W. Langor. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. RESEARCH ARTICLE Launched to accelerate biodiversity research A peer-reviewed open-access journal


Introduction
Th e genus Atomaria Stephens is the nominate genus of the Atomariinae, a subfamily of the family Cryptophagidae, the silken fungus beetles.Th ey are small (1.0-2.0 mm), somewhat shiny, oval-oblong, pubescent beetles, typically found in leaf litter, grass litter, decaying vegetation, and in habitats which promote mycelial fungal growth on which adults and larvae feed (Leschen and Skelley 2002).
Members of this genus are divided into two subgenera, Atomaria s. str.and Anchicera Th omson.Bousquet (1991) reported 12 species in the subgenus Anchicera and 10 in Atomaria s. str. in Canada, although none were recorded as occurring in Atlantic Canada.Poole and Gentili (1996) listed 30 species in Anchicera and 41 in Atomaria s. str.from North America (although at least eight of these names have been synonymized) while Leschen and Skelley (2002) reported that there were 10 species in Atomaria sensu lato in North America (9 described; 1 undescribed).Th is confusion, and disparity in the numbers of species, is one indication that the genus is in need of extensive revision, the last comprehensive North American treatment being by Casey (1900).
In the Palaearctic region, Atomaria is much better known and understood.Recent publications by Lohse (1967) and Johnson (1992) have provided a solid taxonomic foundation for the genus, and Johnson et al. (2007) provided a complete catalogue of the genus in the Palaearctic region.
Th e paucity of knowledge about this genus in North America has impeded the identifi cation of specimens, and limited our understanding of the historical, zoogeographic, distributional, biological, and ecological dimensions of Atomaria.Th e present study is a contribution to the knowledge of this genus in North America.

Methods and conventions
Specimens of Atomaria originating from Atlantic Canada in a variety of collections were examined and identifi ed.Th ese collections yielded 725 specimens; 425 from Nova Scotia, 49 from New Brunswick, nine from Prince Edward Island, and 242 from Newfoundland and Labrador.Abbreviations (largely following Evenhuis 2009) of collections consulted and referred to in this study are:

AAFC
Agriculture and Agri-Food Canada, St. John's, Newfoundland and Labrador, Canada

Results
As a result of the present investigation, ten species of Atomaria have been recorded in Atlantic Canada; seven in New Brunswick, ten in Nova Scotia, one on Prince Edward Island, fi ve on insular Newfoundland, and four in Labrador ( Atomaria apicalis is newly recorded in insular Newfoundland, New Brunswick, Nova Scotia, and Atlantic Canada (Fig. 16).We have examined the holotype of Atomaria ovalis Casey 1900 deposited in the Smithsonian Institution and have found it to Figure 12.Adeagus illustrations of Atomaria species.12.1 Atomaria apicalis 12.2 Atomaria ephippiata 12.3 Atomaria fuscata 12.4 Atomaria lederi 12.5 Atomaria lewisi 12.6 Atomaria pusilla 12.7 Atomaria testacea 12.8 Atomaria nigrirostris 12.9 Atomaria wollastoni.Adapted from Sjöberg (1947), Lohse (1967), Johnson (1970Johnson ( , 1971) with additional material.Note: no illustration of the adeagus of A. distincta was available.be identical in all respects to A. apicalis Erichson.We therefore designate A. ovalis syn.n. as a junior synonym of A. apicalis.
In North America this species has previously been reported from Connecticut, Indiana, Iowa, Maine, Manitoba, Massachusetts, New Hampshire, New York, Québec (Blatchley 1910;Britton 1920;Leng 1920;Procter 1946;Bousquet 1991;Downie and Arnett 1996;Chandler 2001).It is widely distributed in the Palaearctic region being found throughout Europe and North Africa, east across Siberia to the Russian Far East, across the Middle East, to Central Asia, Mongolia, and Fujian in China (Johnson et al. 2007).Johnson (1993) reported that it was, "a grassland species which has been recorded especially around farms, gardens and parks but often occurs in other habitats.It has been collected in man-made heaps of refuse, especially cut vegetation, grass, compost and dung heaps, fl ood debris, and more rarely on carrion and rotting fungi." Description: A variable species; head, pronotum, and elytra piceous to castaneous or (more rarely) black; elytra sometimes paler in apical 2/5.Legs, prosternum, and abdominal sterna reddish-testaceous.Pronotum weakly constricted from middle to base; from middle to apex even more strongly.Rarely, in males the basal half of the pronotum is parallel-sided, or very weakly constricted basally.Punctures of the pronotum and elytra very variable; on the base of the pronotum, interspaces between punctures ~ 1.0 times the diameter of puctures.Punctation of elytra similar to that of pronotum, or fi ner and shallower, but always less dense.Distance between furrows of prosternal process approximately half the width of the prosternal process.Body strongly convex in cross-section (Fig. 2).Antennae: antennomere 1 swollen, slightly longer than 2; 3 as long as 2 but narrower; 4-8 short and bead-like; club distinct, antennomeres 9 and 10 slightly transverse (Fig. 1.1).Body: width/length ratio, 0.41; length, 1.3-1.6 mm.Atomaria distincta is newly recorded in New Brunswick, Nova Scotia, and Canada (Fig. 14).Th is Nearctic species has previously been reported from the District of Columbia, Massachusetts, New York, and Québec (Leng 1920;Downie and Arnett 1996).

Atomaria lewisi
Atomaria lewisi is newly reported in New Brunswick, Nova Scotia, Canada, and North America (Fig. 14).Under the name A. curtula it was reported from Connecticut, Ontario (Casey 1900;Leng 1920;Bousquet 1991;Downie and Arnett 1996), and Maine (Procter 1946).In the Palaearctic region it is found throughout Europe, the Russian Far East, Central Asia, Mongolia, China, Japan, and North Korea, south to Bhutan and northern India (Johnson et al. 2007).Lohse (1967) called it an adventive species in Europe, and Johnson et al. (2007) referred to it as cosmopolitan.In Nova Scotia it has been found in coniferous and mixed forests, in boggy areas, on Craetegus sp.(Rosaceae), and on compost.Johnson (1993) reported that it was, "a grassland species which has been recorded especially around farms, gardens and parks but it often also occurs in other habitats.It has been collected in man-made heaps of refuse, especially cut vegetation, hay, grass, and compost." Description: Dorsum and venter brownish-yellow or reddish-yellow throughout, including legs.Head moderately densely, moderately fi nely punctate.Pronotum moderately densely and moderately coarsely punctate; interspaces 0.5 times the diameter of punctures; base with a distinct fl attened depression.Elytra somewhat more fi nely and sparsely punctate; interspaces 1.0-1.5 times the diameter of punctures; elytral margins strongly rounded; setae rather long and prominently erect giving a "bristling" appearance (Fig. 7).Antennae: antennomere 1 long, swollen, and curved, apex nearly 1.5-2.0times the width of base, 1.5 times longer than 2; 3 the same length as 2 but more slender; 4-8 almost equal in length and bead-like; club distinct; antennomeres 9 and 10 slightly transverse (Fig. 1.6).Body: width/length ratio, 0.46; length, 1.3-1.6 mm.September 30, 1972 (1, MMUE).
Atomaria pusilla is newly recorded in New Brunswick and Nova Scotia (Fig. 15).In North America it has been recorded in Alaska, British Columbia, Connecticut, Idaho, Indiana, New York, Ohio, Oregon, Québec, and Washington (Blatchley 1910;Britton 1920;Notman 1920;Hatch 1961;Bousquet 1991;Williams et al. 1995;Downie and Arnett 1996).Blatchley (1910) referred to it as a "European" species and Bousquet (1991) listed it as "probably introduced" in North America.In the Palaearctic region it is found throughout Europe (including Turkey), across North Africa, and in central Asia in Iran, Afghanistan, and Kazhakhstan, northeast to Mongolia and the Russian Far East (Johnson et al. 2007).Blatchley (1910) reported it from the borders of a sphagnum marsh and in other damp vegetable debris.In New Brunswick it was found in a coniferous forest on a decaying gill fungus.Johnson (1993) reported that it was, "a grassland species which is found especially around farms and gardens and only rarely elsewhere, It has been collected in man-made heaps of refuse, cut vegetation, hay, grass, and compost heaps.

Atomaria testacea
Atomaria nigrirostris is newly recorded in Labrador, insular Newfoundland, Nova Scotia, and Canada (Fig. 16,17).In North America, it has previously been recorded in Alaska (Leng 1920;Bousquet 1991) under the name Atomaria fuscicollis Mannerheim, 1852, synonymized by Johnson et al. (2007).In the Palaearctic region it is found throughout Europe (including Turkey), in Algeria in North Africa, across Siberia to the Russian Far East, south to Mongolia, and in central Asia in Iran and Uzbekistan (Johnson et al. 2007).In Atlantic Canada it has been collected in eastern hemlock, red spruce, and mixed forests, along a stream, and in a gypsum sinkhole.Lohse (1967) reported it in Europe from along rivers, under leaves.Johnson (1993) reported that it was, "a woodland species, mostly associated with broadleaved trees, it occurs on and under dead wood on the ground, in moss, leaf litter, fl ood refuse and general ground litter.It also occurs under hedgerows." Description: Head, pronotum, and pro-, meso-, and meta-sterna piceous brown; elytra and abdominal sterna a slightly paler, fuscous brown; elytra becoming slightly paler in apical half.Head, pronotum, and elytra moderately densely, moderately strongly punctate; interspaces 1.0-1.5 times the diameter of punctures; apex of elytra slightly more fi nely punctate; elytral setae approximately the length of the interspaces, prominent and somewhat erect.Pronotum strongly constricted from midpoint to apex, parallel from midpoint to pronotal base; before base with a strong transverse impression, with several fi ne and sharp longitudinal ridges.Elytra scarcely, or not, wider than pronotum (Fig. 10).Antennae: antennomere 1 long and curved, twice as long as 2 and approximately twice as wide at apex than at base; 2 cylindrical; 3 as long as 2 but more slender; 4, 6, and 8 short and bead-like; 5 and 7 somewhat longer; club distinct; antennomeres 9 and 10 clearly transverse (Fig. 1.7).Body: width/length ratio, 0.31; length, 1.7-1.9mm.11, 2004, August 11-29, 2004, September 22-October 8, 2004, S. Pardy, subarctic black forest, pitfall (19, MUN);St. Lewis, August 25-September 7, 2004, S. Pardy, heath, pitfall (1, MUN).NEWFOUNDLAND: Picadilly, July 7, 1949, E. Palmen Atomaria wollastoni is newly recorded in Labrador, insular Newfoundland, and Nova Scotia (Fig. 13, 17).Dollin et al.'s (2008) records of A. ochracea are attributable to A. wollastoni.Leng (1920) reported it from "Canada."In Europe this species has a northern distribution having been recorded in central and northern Russia, Scandinavia, Estonia in the Baltic region, Great Britain, Ireland, the Netherlands, Germany, and France (Johnson et al. 2007).In Atlantic Canada it has been found in coniferous forests consisting of eastern hemlock, balsam fi r, red spruce, and black spruce (Picea mariana (Mill.)BSP., Pinaceae).In Europe, Schiegg (2000) classed it as a stenotopic saproxylic species characteristic of high dead wood connectivity, and noted that it is red-listed in Germany.It is also red-listed in Denmark (Stolze and Pihl 1997).In Norway, Hågvar (1999) found it associated with sporocarps of Fomitopsis pinicola (Fr.)Karst.(Polyporaceae).It would appear to be a characteristic saproxylic species in both Europe and North America.

Discussion
As a result of the present investigation, ten species of Atomaria have been recorded in Atlantic Canada.Of these, six including Atomaria distincta, A. fuscata, A. lederi, A. lewisi, A. testacea, and A. nigrirostris are newly recorded in Canada.Atomaria lederi and A. lewisi are newly recorded in North America.
Th e paucity of knowledge about many of these species in North America, makes determination of the zoogeographic status of some species uncertain (Table 1).Two species, Atomaria ephippiata and A. distincta, are clearly Nearctic, not having been recorded outside this region.Atomaria apicalis and A. pusilla, have previously been categorized as "probably" adventive Palaearctic species by Bousquet (1991).Th e designation of Atomaria apicalis, however, was prior to the synonymy with the Nearc-tic Atomaria ovalis (in the present study); consequently this designation needs to be re-evaluated since the wide distribution of A. apicalis is more indicative of a native Holarctic species.Atomaria fuscata has a wide distribution in North America on both Pacifi c and Atlantic coasts, and in the interior of the continent, also suggestive of a native Holarctic species.Th e northern boreal distributions of Atomaria lederi and A. wollastoni in the Palaearctic region could be indicative of species with a Holarctic distribution.However, there are very few records of these species in North America.Atomaria nigrirostris is widely distributed in the Palaearctic region, and records in North America (Alaska, Labrador, Newfoundland, and Nova Scotia) are consistent with a Holarctic distribution.Atomaria lewisi and A testacea are widely distributed in the Palaearctic region, but have only been reported from a limited number of locations in North America -possibly indicative of adventive species on this continent.Given the limited knowledge about this genus in North America, and the considerable taxonomic confusion that still exists, the zoogeographic status of all these species should be re-evaluated in the future when more information is available and the genus is better understood.
Within Atlantic Canada, few generalizations can be made with respect to the distribution of species as indicated in Figs [13][14][15][16][17]A. ephippiata,A. fuscata,A. nigrirostris,and A. wollastoni are represented by a substantial number of records and appear to be relatively widely distributed throughout Atlantic Canada (Figs 13,16).All but A. apicalis are also found in southern Labrador (Fig. 17).Atomaria lederi, A. lewisi, and A. testacea are represented by a moderate number of records and generally distributed in Nova Scotia (although A. lewisi has not been found on Cape Breton Island), and the latter two species have additionally been collected in New Brunswick (Figs 14,15).Atomaria distincta, and A. pusilla are represented by a small number of records and appear to be relatively restricted in their distribution (Figs 14,15).However, collecting eff ort for this genus has been far from adequate in all areas of the region, with the possible exception of the mainland of Nova Scotia.Consequently generalizations about their distribution or abundance in the region must be provisional.Th e possibility of additional species occurring in the region has certainly not been excluded.Further collecting is clearly indicated in order to gain a better understanding of the members of this genus in Atlantic Canada.
It is evident that there are diff erences in habitat preferences amongst these species.Atomaria ephippiata, A. fuscata, A. lewisi, and A. testacea appear to be eurytopic species found in a wide variety of forested and open habitats; Atomaria lederi and A. wollastoni have been principally collected in coniferous forests, whereas Atomaria nigrirostris has been found in coniferous, deciduous, and mixed forests.All three appear to be primarily saproxylic species.Atomaria apicalis, A. distincta, and A. pusilla are all primarily found in grasslands and other open habitats.Atomaria fuscata, A. ephippiata, A. lewisi, and A. testacea have all been collected in compost heaps in this region, and A. distincta, A. fuscata, A. ephippiata, and A. testacea have all bean found in seashore, salt marsh, and beach drift environments.At least in Great Britain and Ireland, A. pusilla appears to be primarily a synanthropic species (Johnson 1993).Further bionomic investigations should be conducted to better understand the macro-and micro-habitat preferences of these species and the ecological roles that they play in their respective environments.