Anamorph: not known.
Teleomorph: ascomata perithecia, 250-350 µm diam., scattered or in clusters, subepidermal, becoming superficial by rupture of the overlying host epidermis, globose, black, with an elongate central to slightly eccentric cylindrical neck to 1.5 mm long and 50-70 µm diam., lined internally with hyaline periphyses. Peridium composed of and outer layer of thick-walled dark brown hyphae 2-3 µm diam., an middle layer of dark brown thick-walled angular cells 8-10 µm diam. and an inner layer of flattened thin-walled angular tissue, the neck hyphal in construction and somewhat paler in the ostiolar region. Interascal tissue not seen. Asci 70-85 x 8.5-10 µm, cylindrical to cylindric-saccate, thin-walled, not fissitunicate, with a short evanescent stalk allowing mature asci to float freely in the ascomatal cavity, the apex obtuse, with a refractive ring ca 1 µm diam. and 2 µm thick that does not stain in iodine, 8-spored. Ascospores parallel in the ascus, 62-70 x 2-2.5 µm, filiform, becoming sigmoid after release from the ascus, usually 3-septate, hyaline to pale straw, smooth- and thin-walled, without an epispore, gelatinous sheath or appendages.
Not formally assessed; currently with a very restricted GBI distribution but perhaps overlooked. It is common within its known range.
Plagiostoma immersa seems very similar to this species, but does not have an elongate neck (Dennis 1975). More research is needed.
A saprotroph on dead stems of herbaceous plants; reported from Anthriscus sylvestris, Heracleum sphondylium, Smyrnium olusatrum and Urtica dioica.
Currently known from VC1 W Cornwall and VC3 S Devon. A report from New Guinea (Walker 1980) needs confirmation.