Hypogymnia tubulosa (Schaerer) Havaas forme corticole.
Thallus foliose, forming irregular rosettes, 5-10 cm across, lobes hollow, swollen and folded, gutter-shaped, 1-3 mm wide, arranged like fingers, apices upturned, soralia developed at margin of lobes apices, at first as brown bugs becoming farinose and capitate, grey-greenish, upper surface pale grey, grey-bluish, grey-greenish, lower surface blackish towards the center, margin brownish. Apothecia very rare, 2-7 mm diam., disc brown reddish. Ascospores colourless, almost globose, Photobiont: Chlorococcoid. Cortex : C-, K+ yellow; medulla and soralia : C-, K-, KC+ yellow > red, Pd-. This species grows on bark of trunks and main branches of trees, sometimes at the basis of heaths. N.B. Also common on rocks near the seashore (more frequent on rocks near the seashore than Hypogymnia physodes which is quite similar), but this taxon has a different aspect compared to the one developing on trees. Therefore, for a more precise information, we present it here under the name of Hypogymnia tubulosa f.*