Atheta (Dimetrota) chartersensis Klimaszewski & Webster

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 : 103-106

Taxon classification Animalia Coleoptera Staphylinidae

Atheta (Dimetrota) chartersensis Klimaszewski & Webster sp. n. Figs 96-103

Holotype (male).

Canada, New Brunswick, York Co., Charters Settlement, 45.8395°N, 66.7391°W, 26.V.2008, R.P. Webster, coll. // Mixed forest, in decaying moldy corncobs and cornhusks (LFC). Paratypes: Canada, New Brunswick, Northumberland Co., ca. 2.5 km W of Sevogle, 47.0876°N, 65.8613°W, 28.V.2013, R.P. Webster // Old jack pine forest, in coyote dung (1 ♂, AFC; 1 ♂, RWC). Saint John Co., Chance Harbour off Rt. 790, 45.1391°N, 66.3696°W, 16.IX.2008, R.P. Webster, coll. // Mixed forest, in decaying gilled mushroom (1 ♀, RWC). York Co., New Maryland, Charters Settlement, 45.8395°N, 66.7391°W, 22.VIII.2006, 27.IV.2006, 5.IX.2006, 14.VI.2008, 20.VI.2008, 27.VIII.2008, R.P. Webster, coll. // Mixed forest, in pile of decaying (moldy) corncobs & cornhusks (4 ♂, 5 ♀, RWC); same data except 5.IX.2006 (1 ♀, NBM); same data except 5.VIII.2006, 22.VIII.2006, 6.IX.2006 (1 ♂, 2 ♀, CNC); same data except 27.IX.2005, 20.VIII.2006, 5.IX.2006 (1 ♂, 3 ♀, LFC).

Etymology.

This species is named after Charters Settlement, the locality where the holotype and most of the paratypes were collected.

Description.

Body length 3.4-3.5 mm, narrowly elongate, subparallel; head, pronotum, and most of abdomen except for apical part black, elytra, legs, and antennae brown or light brown (Fig. 96); forebody with minute and sparse punctation, moderately glossy; head slightly narrower than pronotum, angular posteriorly, with small eyes, antennae with articles V–X strongly transverse and progressively more so toward apex; pronotum transverse, as broad as elytra and only slightly wider than head, pubescence directed outward laterally from midline of disk; elytra with pubescence directed posteriad; abdomen at middle as broad as elytra, broadly arcuate laterally. Male. Median lobe of aedeagus with bulbus broad, oval, tubus short, triangular in dorsal view (Fig. 97), and straight and strongly produced ventrally at apex in lateral view (Fig. 98); internal sac with two elongate sclerites in bulbus and complex structures in tubus (Figs 97, 98); tergite VIII bluntly truncate apically with angular lateral edges (Fig. 99); sternite VIII rounded apically and slightly pointed (Fig. 100). Female. Tergite VIII truncate apically (Fig. 101); sternite VIII broadly rounded apically (Fig. 102); spermatheca with elongate club-shaped capsule and arcuate stem looped and twisted posteriorly (Fig. 103).

Distribution.

Known only from NB, Canada.

Natural history.

Most adults were collected from a pile of decaying moldy corncobs and cornhusks near a composter adjacent to a mixed forest in a residential area. Two individuals were collected from coyote dung in an old jack pine forest; another from a decaying mushroom. Specimens were collected during April, May, June, August, and September.

Comments.

This species belongs to the Modesta group of Atheta (Dimetrota) , with three currently known species: Atheta (Dimetrota) modesta (Melsheimer), Atheta (Dimetrota) pseudomodesta Klimaszewski, and the present new species. All three species share similar body characteristics, similar shape of the spermatheca, ventrally strongly produced apex of the median lobe of the aedeagus, and truncate apical margin of male tergite VIII with angular lateral edges forming more or less distinct teeth. Atheta chartersensis differs from Atheta modesta and Atheta pseudomodesta by narrower body (Fig. 96); elytra dark reddish brown mottled with black, which is slightly contrasting with the color of head and pronotum (elytra is light reddish yellow in the other two species and strongly contrasting with color of head and pronotum); by elytra equal in length to pronotum (elytra is longer than pronotum in the other two species), antennae are dark and II-III basal articles slightly paler and articles VII-X strongly transverse (slightly transverse or subquadrate in the other two species and articles I-III light yellowish red strongly contrasting with remaining dark brown articles), median lobe has narrower apex and internal sac structures are differently shaped (Figs 97, 98) than those in Atheta modesta and Atheta pseudomodesta . For illustrations of Atheta modesta and Atheta pseudomodesta , see Gusarov (2003a) and Klimaszewski et al. (2007), respectively.