Anamorph: conidiomata acervular, 400-600 (-700) µm diam., irregular in form but usually ± circular, mid to dark brown, opening with irregular splits, on the upper surface of leaves in distinct irregular leaf spots or causing death of the whole organ. Upper wall composed of leaf epidermal cells lined with a thin layer of strongly melanized angular cells, lower wall hardly developed. Conidiophores on a basal layer of thin-walled mid brown angular cells, poorly differentiated and sometimes absent. Conidiogenous cells in a well-developed palisade, 7-15 x 2-4 µm, cylindrical to cylindric-conical, thin-walled, ± hyaline, either not proliferating or proliferating percurrently with 1-2 annellations. Conidia 23-28 x 4-5 µm, cylindric-fusiform, straight or slightly curved, 4-septate, with the three central cells pale brown and the apical cells hyaline, slightly contricted at the septa, with an apical filiform appendage 10-18 µm in length that usually has a single branch, and a slightly shorter eccentrically attached basal appendage that is often unbranched. The branches appear to form at a very late stage of development.
Teleomorph: ascomata perithecia, 110-120 (-150) x 80-100 µm, subglobose to pyriform, formed under a well-developed heavily melanized clypeus slightly larger in diameter than the ascoma. Peridium composed of several layers of flattened cells, not strongly pigmented. Interascal tissue of thin-walled unbranched paraphyses. Asci 70-80 x 9-12 µm, cylindric-clavate, short-stalked, not fissitunicate, the apex obtuse, slightly thickened at the apex with an indistinct ring that is at least usually J-, 8-spored. Ascospores partially biseriately arranged, 19-21 x 4-6 µm, ellipsoidal, sometimes slightly curved, 3-septate, not constricted at the septa, pale brown, quite thin-walled, smooth, without a gelatinous sheath or appendages.
The species is almost certainly introduced along with its host plant.
On leaf spots and died-back areas on living leaves of Callistemon sp.
Only reported from a single site on VC71 Isle of Man.
Probably a necrotrophic parasite, though some of its relatives are secondary invaders of plant tissues killed by other agents.