…writes Lindroth (1969) of Pterostichus (Stereocerus) haematopus in his 1200+ page taxonomic key of Canadian/Alaskan ground beetles.
“Black…upper surface as a rule with metallic lustre (bluish, green, brass or coppery)…”
Black with greeny-metallic lustre – check.
“…elytra sometimes rufinistic [reddish]”.
Well that’s quite different, isn’t it?
Ok, reddish – check.
These two again from the side:
Believe it or not, these two beetles are the same species. This is a great example of why a well-assembled taxonomic key is critically important to making accurate identifications. I had rough-sorted (i.e., “guesstimated/eyeballed”) these beetles into different groups initially, but the reddish-brownish one (of which there are few) just kept keying out the same as the more prevalent metallic version. I checked in with the experts at the Canadian National Collection to make sure I hadn’t goofed – and I hadn’t.
The key I’m using for my ground beetles was written by Charles H. Lindroth over the course of about eight years, and represents the sum of several “smaller” publications. It is truly a magnum opus in the world of beetles (indeed, of entomology) and is still considered the ultimate reference for this family, even after 35+ years of new research and updated phylogenetic/taxonomic work.
(For Morgan: Taxonomy FTW!)
Lindroth, C.H., 1961-1969. The ground-beetles (Carabidae, excl. Cicindelinae) of Canada and Alaska. Opusc. Entomol. Suppl. 20,1-200; 24,201-408; 29,409-648; 33, 649-944; 34, 945-1192; 35, I-XLVIII.