Haematomma sorediatum R. W. Rogers
Haematomma leprarioides auct. non (Vain.) Vain.
Haematomma puniceum auct. eur.
Thallus crustose, thin, more or less continuous to slightly rimose, pale greyish, dull whitish but often white, prothallus grey-black effuse though clearly visible, covered with minute rounded to punctiform soralia, 0.1-0.5 mm diam., producing farinose to granular soredia, pale yellowish. Apothecia very rare, and when present, scarce and uncompletely developed, sessile, 0.2-0.8 mm diam., disc flat, bright scarlet, exciple smooth to weakly sorediate, whitish. Ascospsores elongate, apices not pointed, 9-12 (16)-septate, 60-80 x 4-5 µm. Photobiont: Trebouxioid. Thallus and soralia : C-, K+ pale yellowish, KC+ yellow, Pd+ pale yellow, apothecia disc : K+ dark purple. Very rare, on more or less smooth bark trees in humid woodlands, usually near the river banks. N.B. This species might not be as rare as usually stated. In fact sterile specimen are almost impossible to identify in the field and the fertile specimen are far less common. N.B. It probably corresponds to the rather common fertile form of Lecanora punicea described during the 19th century in the Finistère by the CROUAN brothers in their Florule du Finistère.*