Phacothecium varium (Tul.) Trevis.

Unlichenized lichenicolous ascomycete.

    No thallus, the hyphae of this fungus being disseminated in the medulla of the thallus of the host and very little visible. Ascocarps appearing as small black warts piercing the surface of the host thallus, 0.2-0.6 mm wide, 0.2-0.3 mm high, sometimes in clusters. The fertile tissue seems to be enclosed in a black "theca". Clavated asci with 8 spores, 45-60 x 18-20 µm according to the literature. Ascospores thick-walled, hyaline (greyish in decay), oblong with rounded ends (in "pharmaceutical capsule"), 3-septate, 12-18 x 5-6 µm according to the literature, 15-18 x 5-8 µm according to our measurements. Species with oceanic trends, parasymbiotic of thalli of Xanthoria and especially thalli of Xanthoria parietina s.l., in particular by the sea in Brittany.