A. chloroconium A. inquinans A. karelicum A. marcianum A. sessile A. yunnanense Acolium is a genus of lichenized fungi in the family Caliciaceae.

[2] The genus was originally proposed as a subdivision of Calicium by Erik Acharius in 1808,[3] and promoted to generic status by Samuel Frederick Gray in 1821.

The true exciple is consistently thick, particularly at the base, and has a blackish-brown hue, occasionally displaying a white or grey powdery appearance.

They possess a single functional wall layer and disintegrate early on, releasing spores into a dry, black, powdery mass called a mazaedium.

They exhibit a slight or pronounced constriction at the septum and have a thick, dark brown wall adorned with unique ornamentation such as irregular cracks, warts, or parallel ridges.