Mamiania fimbriata
Anamorph: Conidiomata acervular, subcuticular, the upper wall formed of pale brown angular cells. Conidiophores absent. Conidiogenous cells formed directly from the lower wall tissue, 4-6 x 2.5-3.5 µm, ampulliform, proliferating percurrently with periclinal thickening, collarettes minute. Conidia 7.5-13.5 x 1-1.5 µm, fusiform to cylindric-acicular, straight or slightly curved, hyaline, aseptate, thin-walled, without a gelatinous sheath or appendages.
Teleomorph: stromata developing in yellow to brownish indeterminate spots on leaves, 1-3 mm diam. and 500-600 µm deep, usually lenticular, occupying the entire depth of the host leaf and forming a raised pustule on both sides, black, composed of an outer layer of dark thick-walled cells 50-100 µm thick and the interior whitish and composed of loosely arranged thinner-walled cells, containing 1 to ca 15 ascomata in a single layer. Ascomata perithecia, globose or oblate, blackish, with short to elongate and straight or curved necks developing centrally, immersed in the stroma with the necks emergent separately on the lower surface of the leaf. Peridium 25-40 µm thick, composed of 5-7 layers of slightly compressed dark cells, neck wall composed of elongate cells. Interascal tissue absent, but neck periphysate. Asci 33-38 x 8.5-11 µm, cylindrical to cylindric-clavate, with a single discernable wall layer, with a I- refractive apical ring, 8-spored, becoming detatched within the perithecial cavity. Ascospores 7.5-9 x 3.5-4 µm, cylindric-ovoid or ellipsoidal to narrowly ellipsoidal, straight or curved, sometimes inequilateral with one side straighter than the other, hyaline, smooth, biguttulate, with a submedian septum dividing the spore length in about a 4:1 ratio, without a gelatinous sheath or appendages.
Not formally assessed. There are only two localized records of this species in FRDBI, but it is likely to be under-reported and would probably be considered as Data Deficient.
Production of multiple perithecia in a common stroma within the host leaf separates Mamiania from Gnomonia and its close relatives, though the phylogenetic significance of this distinction has yet to be tested. All of these other species on Carpinus appear to have longer ascospores without a submedian septum.
Stromata develop in living leaves of Carpinus betulus, with the anamorph appearing in late summer in moribund patches on living leaves and the teleomorph on dead overwintered leaves.
In GB&I, recorded only from VC8 S Wiltshire and VC36 Herefordshire.
Presumably a weak pathogen, but information on the disease and its impact on the host is sparse.