Platynus decentis

Size: 9-14.5mm

Seasonality: October-May

Distribution; Canada, Eastern USA, along the Rocky Mountain Range, WA, OR, ID

Information: May be found in agricultural fields, prairies, and under bark and leaf litter in damp forests. Prey upon worms and small, soft-bodied insects like Miridae, and can be found scavenging upon animal carcasses.

Description: body: elongate-ovate, slender, subdepressed. Body fully glossy black, dorsal and ventral faces alike, including all appendages. Base of pronotum constricted, further description included below the lower three photos. Hind angles acute, the proceed to curve inwards slightly, then back out. Cordate. Impressions may be seen on the two basal angles of the dorsal disk. Margins thin, upturned, enclosing the entirety of the pronotal disk. One long, pale seta on either dorsal hind angle apex, inside from the margin. One pale seta of equal length to the hind angle setae on each median of the lateral margins. Each elytron has 8 deep striae, apical margins pointed, rounded off at ends.  Humeral angles wide, rounded, no elytral pubescence. Head black, smooth, no ridges or wrinkles, narrow. Antennal pubescence begins on the second antennomere after the pedicel.

All species in the genus Platynus  are sexually dimorphic: see Agonum tarsal variation

Above three photos in order from left to right; Platynus decentis collected in South Dakota, Platynus decentis collected in Ontario, Platynus decentis collected in New Hampshire. In order by pronotum shape; quadrate, semi-cordate, slender, base not strongly constricted<cordate, slender, base constricted<cordate, broad, base constricted.