Halecania laevis M. Brand & van den Boom

    Thallus crustose quite variable, strongly attached to the substrate, 2-6 cm in diameter, quite thick, strongly rimose to areolate, sometimes subsquamulous in appearance, relatively smooth and without the appearance of "spread toothpaste", grey, bluish grey, brownish grey, olive grey, 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 disk, orange-brown then brownish to blackish, margin quite thick and persistent, lighter (on well-developed apothecia). Asci, 25-35 x 8-10 µm with 8 spores. Colorless spores, elliptic, 1-septate, 9-11 x 3-3.5 µm with a perispore of 1 µm. Pycnidia sometimes abundant, included in the thallus, pycnospores of 2.5-3 x 1-1.2 µm. No significant colored reactions to the usual reagents. Rare and localized species, slightly nitrophilous, occurring on lightly beaten acid rocks enriched in organic matter at the top of the black belt, most often on the thalli of Verrucaria and black Hydropunctaria.

N.B. Very similar to Halecania ralfsii from which this species was only recently distinguished and with which it sometimes comes in mixture and which is distinguished above all by its orange P+ reaction (perhaps a chemotype?), its thallus with the appearance of "spreading toothpaste", its slightly larger spores and its occurrence on rocks very exposed to waves.

N.B. the authors of this species report that before being described it could have been confused in the field with certain forms of Catillaria chalybeia but this latter species does not have the same colorations, occurs higher on the shore and its spores do not have a perispore.