Atheta (Dimetrota) ellisi Klimaszewski and Chandler, 2023

Klimaszewski, Jan, Chandler, Donald S., Davies, Anthony & Bourdon, Caroline, 2023, Aleocharine rove beetles of New Hampshire, USA: new taxa and new records (Coleoptera, Staphylinidae, Aleocharinae), Zootaxa 5364 (1), pp. 1-141 : 26-27

42. Atheta (Dimetrota) ellisi Klimaszewski and Chandler , sp. n.

Figs. 3a – d , Table 1

Holotype (male). USA, New Hampshire, Coos Co.: 17 km S Gorham, Glen Ellis Falls , 1900’, 8.IX.1987, J.M. Campbell and A. Davies, sifting litter by stream ( CNC).

Etymology. The name of this species is derived from where the holotype was found: Glen Ellis Falls in Pinkham Notch of the White Mts. in New Hampshire.

Diagnosis. It may be distinguished from all but one Nearctic species, Atheta cadeti Klimaszewski and Godin , by the deeply emarginate apical margin of male tergite VIII ( Fig. 3c ). Atheta cadeti also has a differently shaped median lobe of the aedeagus with ventral margin of tubus straight and apex slightly pointed ventrad ( Fig. 3b ), tubus in A. cadeti is angularly produced ventrad in mid-length; and antennomeres V-X are subquadrate to slightly transverse in A. ellisi ( Fig. 3a ), and strongly transverse in A. cadeti . For illustrations of A. cadeti see Klimaszewski et al. 2021.

Description. Body length 3.5 mm; moderately convex, moderately glossy, narrowly subparallel, head slightly narrower that pronotum, pronotum slightly narrower than elytra, elytra slightly broader that base of abdomen ( Fig. 3a ); integument dark brown with paler (dark reddish) elytra and legs; forebody moderately densely pubescent, pubescence of pronotum directed laterad from midline and on elytra latero-posteriad, punctation fine, forebody microsculpture hexagonal in shape; head subparallel posteriad, eyes about as long as posterior region of head, slightly expanded outside contour of head; antennomeres IV–X subquadrate; pronotum slightly transverse, broadest in apical third, arcuate laterally; elytra at suture longer than pronotum along midline, without distinct postero-lateral emargination; abdomen subparallel, sides broadly arcuate. Male. Tergite VIII transverse, apical margin deeply emarginate ( Fig. 3c ); sternite VIII elongate, parabolic apically, antecostal suture close to base of sternite ( Fig. 3d ); median lobe of aedeagus in lateral view with ovoid bulbus and narrow crista apicalis in ventro-anterior part of bulbus; tubus narrow, straight and slightly ventrad pointed apex, internal sac with course membrane dorso-apically ( Fig. 3b ). Female. Unknown.

Distribution. Known only from the Glen Ellis Falls area in Pinkham Notch of the White Mts., New Hampshire, USA.

Comments. There is only one other Nearctic Atheta species with the male tergite VIII deeply and broadly emarginate ( A. cadeti Klimaszewski and Godin ), but it has a differently shaped median lobe of the aedeagus and has different body characteristics. The shape and structures of median lobe of aedeagus of A. ellisi are somewhat similar to those of A. metlakatlana Bernhauer , recorded from British Columbia. However, in addition to the different shape of tergite VIII, A. ellisi has finer and much sparser (also non-asperate) pronotal punctures and a differently shaped pronotum.

Figures

FIGURE 3a–d. Atheta (Dimetrota) ellisi Klimaszewski and Chandler, sp. n.: (a) habitus in dorsal view; (b) median lobe of aedeagus in lateral view; (c) male tergite VIII; (d) male sternite VIII. Scale bar for habitus = 1mm; remaining scale bars = 0.2mm.