Acrotona subpygmaea (Bernhauer, 1909),

Webster, Reginald P., Klimaszewski, Jan, Bourdon, Caroline, Sweeney, Jon D., Hughes, Cory C. & Labrecque, Myriam, 2016, Further contributions to the Aleocharinae (Coleoptera, Staphylinidae) fauna of New Brunswick and Canada including descriptions of 27 new species, ZooKeys 573, pp. 85-216: 95-98

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Acrotona subpygmaea (Bernhauer, 1909)


Taxon classification Animalia Coleoptera Staphylinidae

Acrotona subpygmaea (Bernhauer, 1909)  Figs 50-58

Acrotona subpygmaea  (For details, see Brunke et al. 2012)


Body length 2.6-2.8 mm, moderately narrow, uniformly dark brown except for paler legs and basal antennal articles (Fig. 50); integument moderately glossy, densely punctate and pubescent, pubescence short and adhering to body; head about one-third narrower than pronotum, rounded posteriorly with eyes shorter than postocular area; antennae with articles V–X transverse; pronotum broad, transverse, as wide as elytra at base and posterolateral margin slightly angulate, not completely rounded; elytra as long as pronotum or slightly longer; abdomen subparallel for most of its length. Male. Median lobe of aedeagus with bulbus broad, oval, tubus narrowly triangular in dorsal view (Fig. 51), arcuate ventrally in lateral view (Figs 52, 53); internal sac structures as illustrated (Figs 51-53); tergite VIII slightly pointed apically (Fig. 54); sternite VIII elongate, truncate apically and bearing sinuate base (Fig. 55). Female. Tergite VIII more apically produced than that of male (Fig. 56); sternite VIII deeply emarginate apically (Fig. 57); spermatheca with club-shaped capsule and coiled stem (Fig. 58). This species has genitalic structures almost identical to those of Acrotona brachyoptera  , but differs by its broader body, longer elytra, and darker and more uniform body color.

Material examined.

New Brunswick, Northumberland Co.,12 km SSE of Upper Napan, 46.8991°N, 65.3682°W, 7.VI.2006, R.P. Webster, coll. // Eastern white cedar swamp, in moist leaf litter (2 ♂, LFC); ca. 2.5 km W of Sevogle, 47.0876°N, 65.8613°W, 28.V.2013, R.P. Webster // Old jack pine forest, vernal pond margin, in leaf litter (1 ♂, AFC, 1 ♂, RWC). Queens Co., Canning, Grand Lake near Scotch town, 45.8762°N, 66.1817°W, 25.V.2006, R.P. Webster // Silver maple swamp near lake margin, margin of vernal pond in moist leaves (2 ♂, 1 ♀, RWC); ca. 3.5 km W of Lower Gagetown, 45.7497°N, 66.1846°W, 13.V.2008, R.P. Webster // old red oak/ red maple forest, in moist leaves on margin of vernal pond (1 ♂, RWC); near Queenstown, 45.6904°N, 66.1455°W, 13.V.2008, R.P. Webster // old-growth hardwood forest, in leaf litter near seepage and brook (1 ♂, RWC). Restigouche Co., Jacquet River Gorge P.N.A., 47.7491°N, 66.1114°W, 24.VI.2008, R.P. Webster // Hardwood forest, among moist leaves in dried snow-melt pool (1 ♀, RWC). Sunbury Co., Maugerville, Portobello Creek N.W.A., 45.9031°N, 66.4268°W, 11.IX.2006, R.P. Webster, oak & red maple forest, on gilled mushrooms (1 ♂, LFC; 1 ♂, RWC); Acadia Research Forest, 46.0188°N, 66.3765°W, 18.VI.2007, R.P. Webster, coll. // Road 16 control, mature red spruce & red maple forest, sifting leaf litter & moss (2 ♂, AFC); same data but 14.V.2007 // sifting leaf litter (1, sex undetermined, AFC); Acadia Research Forest, 46.0173°N, 66.3741°W, 17.VIII.2007, 18.IX.2007, R.P. Webster, coll. // Road 16 Regenerating Forest, 8.5 year old regenerating mixed forest // in sphagnum and leaf litter at bottom of old tire depression (1 sex undetermined, 1 ♂, AFC). York Co., trail to Browns Mtn. Fen, 45.9033°N, 67.6260°W, 2.V.2005, M. Giguère & R. Webster, coll. // Mixed forest with cedar, margin of vernal pond in moist leaf litter (1 ♂, CNC); Fredericton, Nashwaaksis River at Rt. 105, 45.9850°N, 66.6900°W, 6.V.2006, R.P. Webster // River margin, in flood debris on upper river margin (1 ♀, RWC); Charters Settlement, 45.8341°N, 66.7445°W, 22.IV.2005, 27.IV.2005, R.P. Webster, coll. // Mature mixed forest, margin of vernal pond among moist leaves (3 ♀, LFC); Charters Settlement, 45.8340°N, 66.7450°W, 29.V.2008, R.P. Webster // Mature mixed forest, margin of vernal pond among moist leaves (1 ♀, NBM, 1 ♀, RWC); same data but 1.IV.2007 // Mixed forest, under bark of stump sticking out of snow (1 ♀, LFC); Charters Settlement, 45.8286°N, 66.7365°W, Old-growth red spruce & cedar forest, in moss & litter at base of tree (1 ♂, LFC); 9.2 km W of Tracy, off Rt. 645, 45.6837°N, 66.8809°W, 22.V.2008, R.P. Webster, coll. // Carex  marsh adjacent to slow (flowing) stream, in Carex  hummock (1 ♀, LFC).

Natural history.

Most specimens of Acrotona subpygmaea  from NB were found among moist leaves along margins of vernal ponds and snow-melt pools in various forest types. These included an old jack pine ( Pinus banksiana  Lamb.) forest, silver maple ( Acer saccharinum  L.) swamp, an old red oak ( Quercus rubra  L.)/red maple forest, hardwood forests, an eastern white cedar swamp, a mature red spruce and red maple forest, and a mature mixed forest. A few were found in leaf litter near a seepage and brook, in sphagnum and leaf litter at bottom of an old tire depression in a regenerating mixed forest, in leaf litter and moss, in flood debris on an upper river margin, in a Carex  hummock in a Carex  marsh, and in a gilled mushroom. One individual was found under bark of a stump sticking out of snow in early April. Most adults were collected in May, with a few in April, June, August, and September. Brunke et al. (2012) reported this species from similar habitats in ON and Majka and Klimaszewski (2010) reported it in bark of dead white pine in NS.

Distribution in Canada and Alaska.

ON, NB, NS ( Majka and Klimaszewski 2010; Brunke et al. 2012; Bousquet et al. 2013); although previously reported from NB ( Klimaszewski et al. 2005), this was a misidentification by V. Gusarov and is described here as Acrotona brachyoptera  .