Halecania laevis M. Brand & van den Boom

       Thallus fairly variable, crustose, strongly attached to the substrate, 2-6 cm in diameter, fairly thick, strongly rimose to areolate, sometimes scaly in appearance or like "spreading tooth paste", gray, bluish gray, gray-brown, gray olive, more whitish in eroded places; prothallus uncommon, greyish-brown. Apothecia more or less numerous and often poorly developed, applied to the thallus then sessile, 0.2-0.5 mm in diameter, flat disc, orange-brown then brownish to blackish, margin rather thick and persistent, paler (on the well-developed apothecia). Asci, 25-35 x 8-10 µm with 8 spores. Spores colorless, elliptical, 1-septate, 9-11 x 3-3.5 µm with a perispore of 1 µm. Pycnidia sometimes abundant, included in the thallus, pycnospores 2.5-3 x 1-1.2 µm. No significant color reactions to the usual reagents. Rare and localized species occurring on acidic rocks slightly beaten at the level of the top of the black belt, most often on the thalli of black Verrucaria and Hydropunctaria. N.B. Very similar to Halecania ralfsii (sometimes mixed) which is only distinguished by its orange P + reaction and of which it is perhaps a chemotype? NB the authors of this species indicate that before being described it could have been confused in the field with certain forms of Catillaria chalybeia but this last species does not present the same colorations, comes higher on the shore and its spores do not have a perispore.