Lichens marins - Flavoplaca dichroa (Arup) Arup, Fröden & Sochting = Caloplaca dichroa Arup

Flavoplaca dichroa (Arup) Arup, Fröden & Sochting = Caloplaca dichroa Arup

Flavoplaca dichroa (Arup) Arup, Fröden & Sochting

= Caloplaca dichroa Arup

Caloplaca coronata auct. brit.

Caloplaca dichroa Arup

Description

Thallus formed of more or less discontinuous areoles, which quickly disintegrate into blastidia or soredia then into small granules of two colors; yellow or orange-reddish (hence its name!) the two colors can cohabit side by side, sometimes this thallus is very small and not very visible which makes this species very discreet in its habitat. Apothecia usually present, scattered, sessile, 0.5-1 mm in diameter, flat or slightly convex disc, not powdery, smooth or crenate (but not sorediate) margin concolorous to the thallus (therefore two colors: yellow-orange or red - orange). Elliptical, hyaline spores, quite variable but most of which have a thick wall, especially at the level of the central thickening which leaves only a thin thread which gives them a typical "hourglass" appearance, 12-16 x 6-9 µm according to the literature, 10-17 x 7-10 µm with a central thickening of 4-6 µm according to our measurements. K + purple. Nitrophilic species coming in the sun on limestone rocks or walls, more rarely on the concrete or cement, often in the vicinity of Hydropunctaria (Verrucaria) nigrescens,. see Caloplaca coronata with a non-two-colored thallus which is isidiate and whose smaller spore has less thick walls.