Siagonium quadricorne Kirby, 1815

Very distinctive due to head structure. Locally distributed throughout southern England and the midlands, found under damp bark especially during winter. Often common where found.

4-5.5mm. Flat and parallel sided, black or brownish black except as below. At first may be confused with Oxytelinae; the antennae inserted under sides of head in front of eyes, filiform with all joints elongate (much longer in male than female). Without ocelli. Abdominal tergites 2-5 with curved line basally inside the side border but the characteristic appearance of this species will soon be appreciated.

Head broad, produced outside mandibles, greatly so in male where it appears horned. Mandibles prominent, with at terminal horn in male. With a transverse ridge each side from some distance behind eyes. Eyes small and prominent. Thorax transverse, without impressions and constricted broadly, about as broad as elytra. Glabrous, diffusely punctate with large and small punctures. Elytra with a complete punctate sutural stria, laterally with incomplete rows of punctures and apex finely punctured throughout, reddish or reddish brown, often lighter basally. Abdomen pitchy red with strong side borders, the oblique baso-lateral lines on tergites 2-5 will distinguish this from most of the British Staphylinidae. Antennae and legs red. Tarsi 5 segmented.