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Tribe Cychrini

Scaphinotus crenatus ? - Scaphinotus Scaphinotus Beetle and Hitchhikers, Burnaby Lake  - Scaphinotus angusticollis Cychrus tuberculatus - female Cychrus tuberculatus  ? - Cychrus tuberculatus Scaphinotus infletus - male Sphaeroderus stenostomus lecontei? - Sphaeroderus stenostomus Scaphinotus schwarzi - male Scaphinotus
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Coleoptera (Beetles)
Suborder Adephaga (Ground and Water Beetles)
Family Carabidae (Ground Beetles)
Subfamily Carabinae
Tribe Cychrini
Numbers
~90 spp. in 3 genera in our area, 4 genera total(1)
Identification
Key to NA genera(1)
[parts mentioned in the key are rarely seen on live photos]

1. Suture between proepisternum and proepimeron present, at least in medial half of pleuron;
Base of deep labral emargination with two (subg. Maronetus) or four setae;
Penultimate labial palpomere in its middle section with two (subg. Maronetus) or more setae; [Clypeus with distal border not emarginate]; throughout NA ==> Scaphinotus
Suture between proepisternum & proepimeron absent, but area representing proepimeron densly punctate or not; base of deep labral emargination bisetose; penultimate labial palpomere with two or more setae ==> 2
2. Penultimate labial palpomere bisetose; [clypeus with distal medial border emarginated];
Eastern half of NA ==> Sphaeroderus
Penultimate labial palpomere plurisetose; w. NA (BC-CA to MT-UT) ==> Cychrus
Range
Holarctic + adjacent montane Oriental(1)
Habitat
cool damp woods and ravines(1)
Food
mostly snails, some commonly feed on slugs; may also feed on caterpillars, worms and other soft-bodied prey(2)
Remarks
Wings highly reduced; elytra fused. Most species can stridulate when disturbed.(2)
Works Cited
1.American Beetles, Volume I: Archostemata, Myxophaga, Adephaga, Polyphaga: Staphyliniformia
Arnett, R.H., Jr., and M. C. Thomas. (eds.). 2000. CRC Press LLC, Boca Raton, FL.
2.A natural history of the ground-beetles (Coleoptera: Carabidae) of America north of Mexico.
Larochelle and Larivière. 2003. Pensoft Publishers, Bulgaria. 584 pp.