Mycophyscias ascophylli (Cotton) Kohlm. & Volkm.-Kohlm. = Stigmidium ascophylli (Cotton) Aptroot

    Non-lichenized, endosymbiotic marine ascomycete fungus.

   Hyphae of the fungus (symbiotic and endophytic) establish themselves in the host tissues and are visible to the naked eye only as small black dots (pseudothecia) appearing on the surface of the cortex of the fertile receptacles of the host alga. Eight-spored asci with a very thick apex (I-). Cylindrical ascospores, 1-septate, 15-23 x 4.5-6 µm. This species, which appears quite common, is only visible on the fertile parts of the host alga: Pelvetia canaliculata or Ascophyllum nodosum.

_ Should not be confused with Collemopsidium pelvetiae, whose true perithecia are much larger and do not appear on the fertile parts of the alga.

N.B. Symbiotic marine ascomycete and endophyte of a brown macroalga: Ascophyllum nodosum and Pelvetia canaliculata, where it forms a mycophycobiosis ("inverted lichen") of which it is the mycobiont and the brown alga, which is the dominant partner, the photobiont.