Eustrophinae, Gistel, 1856

Pollock, Darren, 2008, Review of the Canadian Eustrophinae (Coleoptera, Tetratomidae), ZooKeys 2 (2), pp. 261-290 : 264-267

Identification key to Nearctic genera and Canadian species of Eustrophinae

1 Outer faces of meso- and metathoracic tibiae with numerous oblique, comblike ridges (as in Fig. 16 )............................................................................. 2

– Outer faces of meso- and metathoracic tibiae with scattered spines but without oblique ridges ( Fig. 15 )......................................................................... 4

2(1) Prothoracic episterna with distinct, transverse suture; dorsal surface dark piceous to black, without brownish iridescence ( Eustrophopsis Champion ).....3

– Prothoracic episterna without transverse suture; dorsal surface distinctly brown, slightly iridescent ....................................... Eustrophus tomentosus Say

3(2) Innermost margins of eyes widely separated by distance greater than length of first antennomere ( Fig. 13 ); entire body dark brown to black, without distinctly contrasting lighter color ventrally or on antennae .............................. .................................................................... Eustrophopsis confinis (LeConte)

– Innermost margins of eyes more narrowly separated ( Fig. 12 ), in some specimens virtually contiguous; if slightly separated, then gap less than length of first antennomere; body dark dorsally, with legs, much of venter and antennomere 11 distinctly contrasting................... Eustrophopsis bicolor (Fabricius)

4(1) Prosternal process narrowed distally, not extending posteriad of prothoracic coxae; elytral punctation coarse, forming distinct striae ( Fig. 7 ) .................... .......................................................................... Synstrophus repandus (Horn)

– Prosternal process widened distally, separating prothoracic coxae; elytral punctation fine to coarse, not forming distinct striae ( Holostrophini ).........5

5(4) Eyes distinctly emarginate ( Fig. 10 ); prosternal process longer, protruding behind posterior edge of prothoracic coxae; elytra dark in color, with 4 subquadrate, lighter colored maculae ( Fig. 3 ) ......... Holostrophus bifasciatus (Say)

– Eyes only indistinctly emarginate ( Figs 8-9 ); prosternal process at most slightly projecting behind posterior edge of prothoracic coxae; elytra uniformly rufous to piceous, without distinctly delimited lighter areas ( Pseudoholostrophus Nikitsky )..................................................................................................... 6

6(5) Dorsal surface finely punctate ( Fig. 1 ), setae short and adpressed against surface; impressions along posterior pronotal margin linear, parallel, distinctly impressed; anterior margin of pronotum not elevated shelf-like above level of head; known only from western North America (in Canada, only British Columbia) ................................... Pseudoholostrophus impressicollis (LeConte)

– Dorsal surface more coarsely punctate ( Fig. 2 ), setae more distinct and at least partly erect; impressions along posterior pronotal margin indistinct; anterior margin of pronotum distinctly elevated above level of head; known only from eastern North America (in Canada, only southern Quebec).......................... ................................................................. Pseudoholostrophus discolor (Horn)

Figures

Figs 8-16. Features of Canadian eustrophines. Figs. 8-14. Frontal view of head (same specimens as in Figs. 1-7). Fig. 8. Pseudoholostrophus impressicollis; Fig. 9. Pseudoholostrophus discolor; Fig. 10. Holostrophus bifasciatus; Fig. 11. Eustrophus tomentosus; Fig. 12. Eustrophopsis bicolor; Fig. 13. Eustrophopsis confinis; Fig. 14. Synstrophus repandus. Figs. 15-16. Hind tibia. Fig. 15. H. bifasciatus; Fig. 16. E. tomentosus.

Figs 1-7. Dorsal habitus of Canadian eustrophines. Fig. 1. Pseudoholostrophus impressicollis, TL = 4.3 mm; Fig. 2. Pseudoholostrophus discolor, TL = 4.8 mm; Fig. 3. Holostrophus bifasciatus, TL = 5.8 mm; Fig. 4. Eustrophus tomentosus, TL = 4.8 mm; Fig. 5. Eustrophopsis bicolor, TL = 5.6 mm; Fig. 6. Eustrophopsis confinis, TL = 5.4 mm; Fig. 7. Synstrophus repandus, TL = 6.8 mm.