Anamorph: Acremonium-like. Colonies 6–15 mm diam. after 14 d. at 25 C on PDA, cottony with rosy-buff aerial mycelium, reverse concolorous. Sporulation on SNA usually abundant, arising directly from agar surface. Conidiophores generally simple, unbranched. Conidiogenous cells 36–53 µm long, width at base 1.5–2 µm, width at tip 1–1.3 µm, cylindrical, collarette not flared, hyaline, proliferating percurrently from a single apical locus. Conidia 4.6–6.7 x 1.2–2 µm, cylindrical, aseptate, smooth, hyaline, without a gelatinous sheath or appendages.
Teleomorph: stromata absent. Ascomata perithecia, 170–200 x 150–180 µm, solitary, superficial, subglobose with a discoidal apex, collapsing laterally when dry, scarlet, smooth-walled. Interascal tissue absent at maturity. Asci 54–66 x 5.5–7 µm, cylindrical to slightly clavate, 8-spored. Ascospores arranged uniseriately, 6.5–8.5 x 3–4 µm, ellipsoidal, slightly constricted at the single median septum, smooth, hyaline, thin-walled, without a gelatinous sheath or appendages.
Not formally assessed. Only one confirmed collection is known, but there are 14 records of Dialonectria episphaeria on species of Eutypa in FRDBI, and some of these may be misidentified.
The related species Dialonectria episphaeria differs most clearly by production of a Fusarium (macroconidial) anamorph rather than the Acremonium-like asexual morph found in Pseudocosmospora eutypae. There are some indications that the fungus host is different, but D. episphaeria is a species complex needing further revision.
The confirmed collection was from Eutypa cf. lata on Crataegus sp., originally identified as Fusarium aquaeductum.
The confirmed collection originated from VC9 Dorset.