Nemania gwyneddii (All Fungi)
Anamorph: Geniculosporium-like. Conidiophores forming in small clumps after 2 wk in culture, more profusely close to teleomorph structures, 2-4 µm diam, decumbent to erect, dichotomously or sympodially branched, not synnematous, often without a well-defined main axis, pale brown. Fertile regions mainly terminal but also intercalary and then separated by smooth sterile areas, proliferating sympodially, geniculate with conspicuous conidial scars. Conidia produced in acropetal succession, 2.5-8.5 x 2-3 µm, ovoid to ellipsoidal, truncate at the base, hyaline to subhyaline, aseptate, smooth, without a gelatinous sheath or appendages.
Teleomorph: stromata forming on decorticated wood, also produced in culture; on wood 11-25 x 3-5 mm, elongate-elliptical in outline, 0.6-2 mm thick, almost applanate, dark purple-brown, becoming black when over-mature. Ascomata scattered, 500-700 µm diam, hardly raising the stroma surface, with conspicuous minutely papillate ostioles. Interascal tissue not seen, presumably due to degeneration of the available specimens. Asci 140-190 x 9-12 µm, cylindrical, long-stalked, the stalk 28-45 µm in length, with an urniform or inverted hat-shaped apical ring structure 5-7 µm high and 3-4 µm diam that stains blue with iodine, 8-spored. Ascospores uniseriately or obliquely uniseriately arranged, 19.5-25.9(-27.5) [mean=22.8, sd=2.03, n=30] x (5.1-)6-9 µm [mean=6.7, sd=0.92, n=30] µm, ellipsoidal to fabiform (inaequilateral) with broadly rounded ends, distinctly wider when mature, with a short fairly conspicuous germ slit 3-4 µm long on the more convex side, pale brown, smooth-walled, aseptate, perispore apparently absent, without a gelatinous sheath or appendages.
Not formally assessed. It has only been reported from single localities in North Wales and SW France. The conservation status of the GB&I site is uncertain, and as the species appears to be restricted to Fraxinus excelsior which is itself threatened by an invasive pathogenic fungus, further research is urgently needed to establish and mitigate conservation threats. The species is externally indistinguishable from other members of the N. serpens complex, so may be under-recorded.
Distinguished from other members of the Nemania serpens complex by its large ascospores with short germ slits.N. aenea has ascospores 14-17.5 µm in length (as opposed to 19.5-27.5 µm for N. gwyneddii), but is otherwise difficult to distinguish.
Stromata develop on rotten wood of Fraxinus excelsior.
In GB&I, reported only from Caernarvonshire (N Wales).