Size: 10.7-11.8mm

Seasonality: November through early June

Distribution; BC, WA, OR, CA

Information: Can most often be found under stones or logs within oak forests, especially where the millipede species Xystocheir dissecta, its primary food source, also occurs. This beetle is a specialized hunter of X. dissecta and is immune to its deadly, defensive secretions of cyanide.

Description: body: elongate-ovate, robust. Dorsal and ventral faces fully glossy black, antennae and palps pale or dark red. Mandibles quite long, straight, then curved like a sickle at the tips; dark red to black. Labrum small, slightly wider than space between the bases of the two mandibles. Smooth ridges span from just behind the eyes to about where the clypeus starts. Rest of head dorsally: smooth.  Eyes somewhat small, bulging from head. Moderate antennal pubescence begins on the third antennomere after the pedicel. Antennae about as long as the distance between the clypeus and the pronotal base. Pronotum and elytra both smooth, black, margins thin but slightly upturned. Pronotum noticeably elongate-cordate, base constricted; hind angles acute, projecting laterally. On either side of the pronotum laterally should one find 2-3 fovea with setae, while P.crassus only have one pair. Abdominal/elytral region ovate, elytra fused, striae absent or nearly so; when present, extremely shallow, in some cases incomplete, 4-5 striae may be seen. This genus is flightless, and sexually dimorphic; males have widened protarsi with ventral pads, while the protarsi of females are not altered in any way.