Gnypeta nigrella

16. Gnypeta nigrella (LeConte)

(Figs 1, 2, 18, 36 a, b, 164-171, 192)

Tachyusa nigrella LeConte 1863: 29; Bland 1865: 412; Moore and Legner 1975: 422. LECTOTYPE (male): UNITED STATES OF AMERICA: “in original description: “middle and Western States”; original labels: male; nigrella Lec.; Type 6247; Aug.-Dec., MCZ Image Data Base (MCZ). Present lectotype designation by J. Klimaszewski, 2008. Examined.

Material examined

Specimens are listed in Appendix A.

Diagnosis

This species can be recognized by the following combination of characters: body length 2.7-3.0 mm (Figs 1, 2, 18); elytra at suture as long as pronotum or slightly longer and about 1/4 wider than maximum width of pronotum (Figs 1, 2, 18); abdomen at base distinctly narrower than elytra and subparallel (Figs 1, 2, 18); antennal article 4 strongly elongate, 5-10 moderately to strongly elongate (Figs 36 a, b); median lobe of aedeagus with apical part triangularly produced with sinuate edges in lateral view (Fig. 164); spermatheca club-shaped, capsule spherical and connected to a narrowly elongate sinuate stem (Fig. 169); male tergite 8 truncate apically and with slight apical emargination (Fig. 167); female sternite 8 with large apical emargination (Fig. 171). Gnypeta nigrella has extremely similar spermatheca, and tergite and sternite 8 are similar to those of G. minuta and G. saccharina. Gnypeta nigrella is distinct by its very short and silky body pubescence and by only a few coarse punctures at the margins of basal tergites (Fig. 1).

Description

Body length 2.7-3.0 mm; dark brown to almost black, central and/or posterior portion of elytra often rust brown (Figs 1, 2, 18); integument moderately glossy; pubescence yellowish grey and moderately long and dense; antennal articles 4-7 strongly elongate, 8-10 moderately elongate (Figs 36 a, b); head and pronotum of about the same width (Figs 1, 2, 18); elytra and abdomen (less so) wider than either head or pronotum; head rounded posteriorly; pronotum broadest in apical third, pubescence directed posterad along midline and laterad elsewhere; elytra at suture longer than pronotum and about 1/4 wider than maximum width of pronotum, pubescence directed obliquely posterolaterad, in weak wavy pattern medially on each side of disc (Figs 1, 2, 18); abdomen broadening posteriorly, distinctly narrower than elytra at base (Figs 1, 2, 18); metatarsus with basal article slightly longer than the following article (Fig. 1). Male. Tergite 8 emarginate apically (Fig. 167). Sternite 8 elongate and broadly rounded apically (Fig. 168). Median lobe of aedeagus with swollen ventral part of tubus and with produced apex in lateral view (Fig. 164); bulbus moderately large in dorsal view (Fig. 165); internal sac with complex structures as illustrated (Figs 164, 165). Female. Tergite 8 truncate apically (Fig. 170). Sternite 8 broadly rounded posteriorly with deep V-shaped apical emargination (Fig. 171). Spermatheca club-shaped, capsule spherical apically and constricted basally, connected to a narrow tubular and sinuate stem (Fig. 169).

Distribution (Fig. 192)

Gnypeta nigrella is an eastern Nearctic species previously recorded from Massachusetts, Pennsylvania, and Maryland (LeConte 1863; Bland 1865; Moore and Legner 1975). We report this species for the first time from Canada (New Brunswick) and from Vermont in the United States.

Collection and habitat data

Adults captured in New Brunswick occurred on bare, sun exposed, fine sand/gravel near margin of a medium-sized stream, others were found on bare mud and among cobblestones

(also in direct sun) on the shore of the Saint John River, and some from drift material, mostly maple seeds, in the Saint John River. The adults were diurnally active and in company with various Bembidion and Tachyusa species. Collecting period: May, June and July.

Comments

Gnypeta nigrella differs from G. brevicornis and G. uteana by moderately elongate basal article of metatarsus, which is extremely elongate in the two latter species. It differs from other Gnypeta species by its slender body, and almost total lack of punctation in the first three visible tergal impressions.