Family Biphyllidae

Taken from the internet:

General appearance. 2.7-3.5 mm long. Body length/maximum body width 1.5-2.9. Elytral length/pronotal length 2.6-3.2. Base of prothorax not or scarcely narrower than the combined elytral bases. Greatest prothoracic width not narrower or only slightly narrower than the greatest elytral width, or distinctly narrower than greatest elytral width. Beetles elongate-oval to elongate; dorsally flattened; not necked; not waisted to somewhat waisted; decidedly short-legged. Upper surfaces of body non-glabrous; exhibiting stiff, erect, dark bristles, or not bristly; with neither scales nor scale-like setae.
Habitat, ecology. Predacious, or not predacious (?); under bark and associated with fungi.
General comments. Thorax with a ridge, surmounted by a row of bent bristles, down each side; scutellum transverse; tarsi sometimes 4 segmented in non-British species.
Larvae. Larvae predacious, or not predacious (?); in or under bark and in fungi.

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