(male). Canada, Yukon, EMAN Plot (Ecological Monitoring and Assessment Network), mature white spruce and feathermoss forest, 60.5963, -134.9522, 8.VII.2003, 738 m, yellow pitfall trap (LMKM31Y), (LFC).

Yukon, EMAN Plot, 60.5963, -134.9522, 24.VII.2003, 738 m, black pitfall trap (LMKM31B), (ECW) 1 male.

Yukonensis - a Latin adjective derived from the Yukon Territory, Canada.

Body small, subparallel, robust, uniformly dark brown, almost black; length 2.8–3.0 mm; head round in outline and almost as wide as pronotum; antennae with article 4 subquadrate, 5–10 moderately transverse, increasingly wider apicad; pronotum transverse, angular posteriad and slightly narrower than maximum width of elytra; abdomen subparallel, at base as wide as elytra (Fig. 3). MALE: male tergite 8 widely truncate apically (Fig. 32); sternite 8 slightly produced at apex (Fig. 33); median lobe of aedeagus as illustrated (Fig. 16). FEMALE: unknown.

This native Nearctic species is known only from the type locality in the Yukon.

Two adults were collected in July.

The two females are tentatively identified as Gyrophaena criddlei but a male is needed for positive confirmation of this species in the Yukon Territory.

III. Tribe Athetini Casey

(male). Canada, Yukon, Whitehorse, Paddy’s Pond, 60.7067, -135.0917, 27.V.2008, 649 m, litter sifting, mixed aspen and white spruce forest, B. Godin (LFC).

(female). Same data as the holotype (ECW).

This species name is dedicated to Denise Horwood, wife of the second author, who assisted him in numerous aleocharine sample collections.

Body narrowly oval, moderately convex, uniformly black, punctation on forebody fine, dense and not asperate, microsculpture fine but not pronounced; length 2.4 mm; head narrower than pronotum, ratio of maximum width of head to maximum width of pronotum 0.7; antennal articles 7–10 slightly transverse; pronotum moderately transverse, ratio of maximum width to length 1.4, about as wide as elytra; elytra at suture about as long as pronotum; abdomen slightly narrowed posteriad (Fig. 4). MALE: tergite 8 moderately elongate and truncate apically (Fig. 34); sternite 8 widely arcuate apically (Fig. 35); median lobe of aedeagus as illustrated (Fig. 17). FEMALE: tergite 8 moderately elongate and truncate apically, base not sinuate (Fig. 36); sternite 8 widely arcuate apically, base not sinuate (Fig. 37); spermatheca with capsule tulip-shaped and stem coiled posteriorly (Fig. 18).

Bionomics. The specimens were found by sifting forest litter in May.

Comments. The shape of the median lobe of the aedeagus and the spermatheca of Acrotona horwoodae are different from all recorded species of Nearctic Acrotona, and they are generally similar to those of the Palaearctic species Acrotona aterrima Gravenhorst, which is brown and has a much broader body.

Two additional Amischa morphotypes were recognized in the Yukon material on the basis of external body characters and the shape of the spermatheca. They are not included in this account because they are difficult to associate with any of the recorded species. The first morphospecies is represented by three narrowly elongate bicoloured specimens with the head and 4–5 basal abdominal tergites almost black, with the pronotum brown and the appendages and posterior of the elytra light brown, and with the spermathecal capsule moderately elongate with a moderately long apical invagination. The second morphospecies is represented by three specimens, which are broader, with the body uniformly dark brown to almost black, and the spermathecal capsule broader and shorter apically and with a longer apical invagination. Both groups have the apex of tergite 8 deeply notched. We need more specimens and representatives of both sexes to establish the status of these morphotypes.

Canada, Yukon, Whitehorse, Granger, 60.7078, -135.0971, 25.VIII.2007, 657 m, soil sifting, black spruce stand, AWT, B. Godin (LFC).

Canada, Yukon, Whitehorse, Granger, 60.7078, -135.0971, 5.VIII.2007, 657 m, soil sifting, black spruce stand, AWT, B. Godin (ECW) 1 female.

The specific name derives from the name of the type locality, which is Whitehorse, Yukon.

Body narrowly oval, dark brown to black, with bases of antennae and legs rust-brown, surface matte, with asperate dense punctation on forebody and strong meshed microsculpture (Fig. 6); length 1.9–2.0 mm; head narrower than pronotum and elytra, with short postocular area, eyes large and slightly protruding; antennae slender, slightly incrassate apically, article 4 subquadrate, 5 slightly elongate and 6–10 slightly to strongly transverse; pronotum strongly transverse and broadest in the middle; elytra transverse, longer than pronotum; abdomen broadly arcuate laterally (Fig. 6). MALE: tergite 8 transverse and truncate apically (Fig. 40); sternite 8 widely rounded apically (Fig. 41); median lobe of aedeagus with venter of tubus straight and short, and apex sharply produced (Fig. 20). FEMALE: tergite and sternite 8 truncate apically (Figs 42, 43); spermatheca with pipe-shaped capsule and long stem hooked posteriorly (Fig. 21).

This species is similar externally to Atheta (Dimetrota) hampshirensis Bernhauer and Atheta (Datomicra) dadopora Thomson but differs in the shape of the spermatheca and median lobe of the aedeagus, and has a broader body than the latter species.

This native Nearctic species is known only from the type locality in the Yukon Territory.

Adults were captured by sifting soil in a black spruce stand.

(male). Canada, Yukon, Whitehorse, Takhini, hotsprings, 60.8769, -135.3596, 30.IV.2009, 716 m, aspen litter – soil sifting, B. Godin (LFC).

. Canada, Yukon, Whitehorse, Takhini, hotsprings, 60.8769, -135.3596, 19.IX.2009, 716 m, alder/willow litter, soil sifting, B. Godin (ECW) 2 males; same data except: 3.V.2009 (ECW, LFC) 2 females.

The specific name derives from the word micro, meaning small, and elytra, in allusion to the small and short elytra of this species.

Body narrowly subparallel; dark brown, with bases of antennae and legs rust-brown; strongly glossy, with fine and moderately dense punctation on forebody and strong, meshed microsculpture (Fig. 7); head as wide as pronotum and elytra, with long postocular area, eyes moderately small and slightly protruding; antennae slender, slightly incrassate apicad, articles 4–5 subquadrate and 6–10 slightly to strongly transverse; pronotum narrower at base and broadening apicad; elytra transverse, shorter than pronotum; abdomen widest subapically; length 1.9–2.0 mm (Fig. 7). MALE: tergite 8 truncate apically and with crenulation scarcely visible (Fig. 44); sternite 8 widely rounded apically (Fig. 45); median lobe of aedeagus with apex narrow and ventrally produced, athetine bridge well developed (Fig. 22). FEMALE: tergite 8 truncate apically (Fig. 46); sternite 8 truncate and slightly emarginate medially (Fig. 47); spermatheca with pipe-shaped capsule and long, posteriorly-coiled stem (Fig. 23).

This species bears some superficial external similarity to Geostiba and Emmelostiba but has typical Atheta-like genitalia.

This native Nearctic species is known only from the type locality in the Yukon Territory.

Adults were found in aspen, alder and willow litter in March, May and September.

(male). Canada, Yukon, Whitehorse, Paddy’s Pond, 60.7067, -135.0917, 16.IX.2007, 649 m, litter sifting, mixed aspen and white spruce forest, B. Godin (LFC).

Same data as the holotype (ECW) 1 male.

Canada, Yukon, Watson Lake, Watson Creek, 60.12723, -128.8053, 16.VIII.2007, 697 m, mushrooms, B. Godin (LFC) 1 female.

The name of this species derives from the Latin adjective riparius, -a, -um, in allusion to the wet litter where the types were found.

Body small and narrow, subparallel; black, with tarsi reddish-brown; moderately glossy, with fine, dense punctation and meshed microsculpture on forebody (Fig. 8); head approximately as wide as pronotum, depressed medially, eyes slightly protruding; antennae slender, slightly incrassate apicad, articles 4–10 slightly to strongly transverse; pronotum emarginate laterally; elytra broader and longer at suture than pronotum; head, pronotum and base of abdomen of the same width; sides of abdomen subparallel; length 1.9–2.0 mm (Fig. 8). MALE: tergite 8 truncate apically and with smooth margin (Fig. 48); sternite 8 widely rounded apically (Fig. 49); median lobe of aedeagus with apex narrow and ventrally produced (Fig. 24). FEMALE (non-paratype): tergite 8 truncate apically (Fig. 50); sternite 8 broadly rounded apically (Fig. 51); spermatheca slightly distorted but with club-shaped capsule and posteriorly-twisted stem (Fig. 25).

This species differs from other Nearctic Microdota by the combination of body shape, strongly punctate surface and the shape of the median lobe of the aedeagus and spermatheca.

Distribution. This native Nearctic species is known only from the Yukon Territory but it is probably more widely distributed in northern Canada.

Bionomics. The two males were captured in September in wet, organic litter and the female was found in mushrooms in mid-August.

Canada, Yukon, Whitehorse, Paddy’s Pond, 60.7067, -135.0917, 26.V.2007, 649 m, litter sifting, mixed aspen and white spruce forest, B. Godin (LFC).

same label data as the holotype (ECW) 1 male; Watson Lake, Watson Creek, 60.1272, -128.8053, 4.VI.2007, 697 m, deciduous forest soil sifting, B. Godin (ECW) 1 male, 1 female.

This species name derives from the specific name larsoni (Philhygra larsoni Klimaszewski and Langor), and the prefix pseudo (false) in relation to the similarity of the two species in external and, to a lesser degree, genitalic morphology.

Body narrowly subparallel, uniformly black or black with legs and sutural part of elytra reddish-brown (Fig. 9); moderately glossy, with fine, dense punctation and meshed microsculpture on forebody; head round, distinctly narrower than pronotum, with eyes as long as postocular region of head; antennae slender with articles 4–5 elongate, 6–10 subquadrate to slightly transverse; pronotum slightly transverse and almost as wide as elytra; elytra at suture as long as or slightly longer than pronotum; length 2.9–3.0 mm (Fig. 9). MALE: tergite 8 widely arcuate apically (Fig. 52); sternite 8 elongate and rounded apically (Fig. 53); median lobe of aedeagus with apex triangularly produced in lateral view (Fig. 26).

Female. tergite 8 truncate apically (Fig. 54); sternite 8 produced medially (Fig. 55); pygidium with ventral structure weakly sclerotized.

This species is known only from Whitehorse and Watson Lake in the Yukon Territory.

. This species was collected in May and June from ground litter.

Philhygra pseudolarsoni is similar in both external morphology and genitalia to Philhygra larsoni Klimaszewski and Langor. However, it may be distinguished from Philhygra larsoni by the smaller and darker body, quadrate or transverse antennal articles 4–10 and by the median lobe of the aedeagus with a more elongate apical part of the tubus in lateral view.

(male). Canada, Yukon, Whitehorse, Paddy’s Pond, 60.7067, -135.0917, 26.V.2007, 649 m, litter sifting, mixed forest (aspen and white spruce), B. Godin (LFC).

Etymology. This species name is an adjective that derives from the Latin word terra (ground, earth, soil).

Diagnosis. Body narrowly subparallel, head and abdomen black, pronotum and elytra brown, basal article of antenna and legs yellowish (Fig. 10); strongly glossy, with fine, dense punctation and meshed microsculpture on forebody; head round, distinctly narrower than pronotum with eyes as long as postocular region of head; antennae slender with articles 4–5 elongate, 6–10 subquadrate; pronotum slightly transverse and almost as wide as elytra; elytra at suture slightly longer than pronotum; length 2.9–3.0 mm (Fig. 10). MALE: tergite 8 widely arcuate apically (Fig. 56); sternite 8 elongate and rounded apically (Fig. 57); aedeagus with apex of median lobe broadly produced and with tubus constricted basally in lateral view (Fig. 27).

Female. unknown.

Distribution. This species is known only from Whitehorse in the Yukon but it may be more widely distributed in the boreal zone of Canada and Alaska.

Bionomics. This species was collected in May from ground litter.

Comments. This species is unique in the shape of the median lobe of the aedeagus in lateral view.

(female). Canada, Yukon, Herschel Island, 69.5706, -138.902, 13.VI.2007, 5 m, pitfall trap, site dominated by Carex and grasses with presence of willows (ATOR) – alluvial fan, D.G. Reid (LFC).

Labeled as the holotype except: 1–3.VI.2007 (ECW) 1 male; 7.VI.2007 (ECW) 2 males; 10.VI.2007 (CNC) 1 male; 15.VI.2007 (ECW) 1 female; 17.VI.2007 (ECW) 1 male, 1 female; 19.VI.2007 (ECW) 1 female; 16.VII.2007 (LFC) 1 male, 1 female; 21.VII.2007 (ECW) 2 females; 31.VII.2007 (LFC) 1 male; 7.VI.2008 (ECW) 2 females; 7.VII.2008 (ECW) 2 females; 15.VII.2008 (ECW) 1 female; 11.VIII.2008 (ECW) 1 female.

Named for the type locality, Herschel Island.

Body narrow, subparallel, head and pronotum about the same width, elytra and abdomen slightly wider, uniformly black (Fig. 11); surface matte except for slightly glossy abdomen; pubescence fine, punctation weak and moderately dense, meshed microsculpture pronounced on forebody; head round, slightly flattened medially and with eyes about as long as postocular region of head; antennae slender, articles 4–5 slightly elongate, 6–10 subquadrate, last article elongate; pronotum transverse, narrower at base and widest at middle; elytra at suture slightly longer than or as long as pronotum; abdomen subparallel for most of its length; length 2.8–3.0 mm (Fig. 11). MALE: tergite 8 transverse and truncate apically (Fig. 58); sternite 8 slightly elongate and rounded apically (Fig. 59); median lobe of aedeagus with straight tubus in lateral view and with apex short and narrow (Fig. 29), dorsal aspect as illustrated (Fig. 28). FEMALE: tergite 8 transverse and truncate apically (Fig. 60); sternite 8 slightly elongate and rounded apically (Fig. 61); spermatheca S-shaped, capsule consisting of a globular apical part with a small invagination, stem sinuate (Fig. 30).

The following combination of characters distinguishes this species from other congeners: narrow, subparallel and uniformly black body, integument of forebody matte and with dense microsculpture, median lobe of aedeagus narrow apically and spermatheca S-shaped.

This Nearctic species is known only from the type locality on Herschel Island, Yukon.

Adults were collected in June and July on an alluvial fan.

This species is superficially similar to Boreophilia nomensis Casey (=Boreophilia caseyiana Lohse) but differs by its uniformly black body and aedeagus with evenly narrow apical part of median lobe in lateral view.

(female). Canada, Yukon, EMAN Plot, Cadet Camp, 60.5951, -134.9499, 20.IX.2006, 760 m, pitfall trap, mature white spruce and feathermoss forest, coll. EP Yukon, AJK (LFC).

Canada, Yukon, EMAN Plot, Cadet Camp, 60.5951, -134.9499, 29.V.2006, 760 m, pitfall trap, mature white spruce and feathermoss forest, EP Yukon, AHW (ECW) 1 female; same data except: 15.V.2002, JF (ECW) 1 female; 12.VI.2002, EV (ECW) 1 female; 18.X.2002, FD (CNC) 2 females; 8.VII.2003, LMK31Y. LJ (ECW) 1 female; Fireweed Dr., 60.6014, -134.9387, 23.IX.2000, 772 m, pitfall trap, mixed pine and willow forest, EP Yukon (ECW) 1 female; Whitehorse, Granger, 60.7078, -135.0971, 5.VIII.2007, 657 m, soil sifting, black spruce stand, B. Godin (ECW, LFC) 2 females; same data except: 25.VIII.2007 (LFC) 1 female; Whitehorse, Paddy’s Pond, 60.7067, -135.0917, 16.IX.2007, 649 m, litter sifting, mixed aspen and white spruce forest, B. Godin (ECW) 1 female; Upper Liard, Albert Creek, 60.0522, -128.928, 8.VII.2000, 699 m, deciduous litter sifting, B. Godin (ECW, LFC) 2 females.

Named for Douglas Davidge, biological technician (ECW), who supported the second author in his work for 20 years.

Body narrow, subparallel, head narrower than pronotum, elytra and abdomen slightly wider, uniformly brown with appendages yellowish-brown and antennae yellow, or with head and abdomen dark brown and rest of body light brown (Fig. 12); surface moderately glossy; pubescence fine, punctation weak and moderately dense, meshed microsculpture pronounced on forebody; head round, slightly flattened medially and with eyes about as long as postocular region of head; antennae slender, articles 4–5 slightly elongate, 6–10 subquadrate to slightly transverse, last article elongate; pronotum transverse, widest in basal half; elytra at suture slightly longer than pronotum; abdomen broadly arcuate laterally; length 2.8–2.9 mm (Fig. 12). MALE: unknown. FEMALE: tergite 8 transverse and truncate apically (Fig. 62); sternite 8 slightly elongate and rounded apically (Fig. 63); spermatheca S-shaped, capsule elongate, stem short and sinuate (Fig. 31).

The following combination of characters distinguishes this species from other congeners: body narrow, subparallel and brown, with pronotum, elytra and legs lighter, antennae yellowish, surface of forebody moderately glossy and with dense microsculpture, and spermatheca short and S-shaped.

This Nearctic species is known only from the type localities in the Yukon Territory.

Adults were collected from May to September from soil and organic litter.

This species may be easily distinguished by the unique shape of the spermatheca.