On the type of Coprinus megaspermus
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Original description

Coprinus megaspermus P.D. Orton, sp. nov. Fig. 1, f.
Orton, P.D. 1972. Notes on British Agarics 4. In Notes R. bot. Gdn Edinb. 32: 141.

A sociis a sporis vix lentiformibus permagnis facile distinguitur.
Pileus ovoideus, 11/12 mm, dein expansus ad discum depressus, 15-30 mm, juventute fere ferrugineus dein ad discum fulvus vel cinnamomeus et ad marginem versus argillaceo-luteolus et forte plicato-striatus, vix deliquescens circa discum senectute cinnamomeotinctus. Lamellae ± liberae, nigricantes, confertae, L= ca. 50, l= 0-1, ad aciem albidoflocculosae. Stipes 52-60/2 mm; aequalis vel ad basim leviter incrassatus, albus dein pallide argillaceo-luteolus, laevis, ad basim tomentosus. Caro ad discum pilei admodum crassa. Sporae ellipsoideae vel ellipsoideo-ovoideae interdum leviter lentiformes, 15-18/8.5-9.5/10-11 µm (Fig. 1,f), in cumulo nigro-umbrinae. Basidia 4-sporigera. Cystidia aciei lamellarum ± lageniformia, ca. 50-60/18-20 µm, ad apicem conicum vel cylindrico-obtusum 8-10 µm latae. Cystidia faciei lamellarum non vidi. Cellulae cuticulae pilei 12-28 µm latae. Setulae et sphaerocystes desunt. Norfolk. Hedenham Wood, ad terram, 24 X 1971, Orton 4132 (holo. E).

Cap ovoid, 11-12 mm, then expanded with depressed centre, 25-30 mm, ± rusty-tawny at first then fulvous, sienna or cinnamon at centre with outer part clay-buff and strongly plicate-striate, hardly deliquescing, becoming tinged cinnamon around the centre when mature. Gills ± free, blackening, crowded, L= ca. 50, l= 0-1, edge whitish flocculose. Stem 50-60/2 mm, equal or with slightly swollen base, white then discolouring pale clay-buff, smooth, base white tomentose. Flesh rather thick at centre off cap. Spore-print blackish umber.
Spores ellipsoid or ellipsoid-ovoid, sometimes slightly lentiform, 15-18/8.5-9.5/10-11 µm (Fig. 1,f). Marginal cystidia ± lageniform, about 50-60/18-20 µm, apex from conical to cylindric-obtuse and 8-10 µm broad. Facial cystidia not seen. Cap without setules or sphaerocysts; cells of cap cuticle 12-28 µm broad. Norfolk. Hedenham Wood, on soil, 24 X 1971, Orton 4132 (holo. E).

Resembling C. hemerobius in having similarly shaped not or only slightly lentiform spores (Fig. 1,i), but easily distinguished by larger spores (also from 4-spored basidia) and by its deeper coloured cap and probably also its robustness. It belongs to section Hemerobii. In spite of rather scanty material I have no hesitation in describing this as a new species straight away because of its characteristic large spores. The above description may need slight modification when more material has been found, especially as regards size of fruit-body.
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