On the type of Coprinus luteocephalus
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Original description
Coprinus luteocephalus Watling in Notes R. bot. Gdn Edinb. 31: 359. 1972 (Notes on British agarics II). Holotype: Scotland: Midlothian, Penicuik, Glenhorse, on horse dung, 10 Oct. 1968, R.F.O. Kemp, Watling 7360 (culture of holotype?, E).

Coprinus luteocephalus Watling, sp. nov. Fig. lA-E.
Pileus primo glandiformis vel elongato-ellipticus, 8-18 mm altus. 6-16 mm latus. dein expansus. plano-convexus vel umbonatus 8-22 mm, sulphureus vel citrinus interdum ad discum obscurius coloratus vel luteus primo totus sulphureus fibrillosus vulgo ad discum squamis velutinus interdum sordide isabel-lino-tinctus obtectus interdum postremo radialiter plicato-striatus margine fisso revolutoque. Lamellae fere liberae. ex albo dein nigrae, confertae. ad aciem primo albo-flocculosae. Stipes primo 10-20 x 2-2.5 mm, postremo- 60 x 1-1.5 mm (2-3 mm ad basim), subaequalis vel sursum attenuatus. albus vel pallido-griseus. totus fibrillosus cavus ad basim obscuris luteo fibrilloso. Caro tenuis grisea. Sporae eilipsoideae, 10.5-12.5 x 6-7.5 µm. Basidia 4-sporigera. Cystidia aciei lamellarum pyriformia vel iiregulariter vesiculosa 40-45.5 x 35-38 µm; cystidia faciel lamellarum obovata vel irregulariter vesiculosa. Cellulae veli pilei cylindricae vel fusiformes. Typus: Watling 7360 (holo. E).

Pileus elongate slightly constricted about half-way, 8-18 mm high, rapidly expanding to plano-convex 8-22 mm. sulphur to citrine yellow darker and more yellow towards the disc. distinctly umbonaie. becoming more yellow with maturity then isabelline towards the margin, fibrillose scurfy Throughout or more velvety at the disc, striate then sulcate at margin. Stipe up to 60 x l-l.5 mm (2-3 mm at base) developing rapfily, hollow, hyaline or slightly brownish, equal except for slightly bulbous foot which is coated with sulphur to olivaceous hyphae. Gills grey-whitish then dark violaceous black, crowded, whitish floccose at margin when young. Flesh thin, greyish.
Spore-mass violaceous black. Basidiospores dark brown, 10.5-12.5 x 5-7.5 µm, ellipsoid in face-view, slightly flattened in side-view, thick-walled, apiculus small but obvious, germ-pore distinct c. 2 µm broad, central. Basidia 4-spored, 20-25 x 10-12 µm, hyaline in water and ammoniacal solutions. Cheilocystidia vesiculose, few differentiated into a blunt apex, thin-walled, smooth, hyaline in water and ammoniacal solutions, numerous, 40-45 x 35-38 µm. Pleurocystidia sparse, swollen with long blunt neck, obovate, hyaline in water and ammoniacal solutions 85-100 x 40-45 µm, smooth, thick-walled. Brachycystidia 13-18 µm in diameter when fully turgid, ellipsoid, hyaline in water and ammoniacal solutions. Pileal surface of swollen ellipsoid to subglobose cells. 17.5-31.5 µm in diameter, covered in velar remnants. Pileus trama of swollen, elongate cylindric cells with slightly brownish walls. Hymenophoral trama of hyaline, swollen, regularly arranged cells. Veil a mixture of thin-walled, septate filamentous hyphae, 2-3-5 µm broad, with granular or amorphous yellow vacuolar sap, and swollen, elongate-ellipsoid or fusiform cells 10-12 µm broad; hyphal elements retain colour in ammoniacal solutions, irregularly branched and often ornamented with slightly yellowish prismatic deposits. Stipe-cortex of parallel, septate, hyaline, cylindric cells. 7.5-10.5 µm broad; clamp-connections frequent.
Scotland. Midlothian: Penicuik, Glencorse, on horse dung, 10 x 1968. legit R. F. 0. Kemp, Wading 7360 (Type). Further collection on horse dung from England, Cumberland. Wigton; legit R. F. 0. Kemp.

In external appearance, C. luteocephalus resembles C. vermiculifer but differs macroscopically in the distinct sulphur-yellow fruit-body which retains the yellow coloration even into maturity. Microscopically, it differs primarily in the lack of thick-walled, diveniculate hyphae in the veil. many of which are filled or ornamented with prismatic yellow material. This species fruits well in pure culture on various media. It produces clamp-connections in culture and the monocaryotic hyphae produce wet oidial colonies. It is tetrapolar (pers. communication R. F. 0. Kemp) and incompatable with C. vermiculifer.
FIG. I. A-E, Coprinus luteocephalus'. A, habit sketch; B, cheilocystidia: C. basidiospores: D, Pleurocystidia; E, veil constituents.

Observations:
Spores [20,1,1] 9.6--11.8 x 5.9--6.8 µm, dark red-brown, ellipsoid; Q= 1.55--1.75, av. Q= 1.65; av. L= 10.3, av. B= 6.3 µm. Basidia 14--28 x 7--9 µm, 4-spored, surrounded by (3--)4--5 pseudoparaphyses. Germ pore central, c. 1.5 µm in diameter. Pleurocystidia 70--160 x 25--55 µm. Cheilocystidia 40--70 x 35--45 µm. Veil thin-walled, not coloured, some hyphae slightly thick-walled and yellowish, 2--8 µm wide. Pileipellis made up of elongate, swollen cells, 12--28 µm wide. Clamp-connections present.

Notes: the status of the material studied is not clear. The folder of the type material consists of three envelopes; one, marked 'holotype (Watling 7360)' is empty, while the other two, containing the material studied, lack annotation. Since the type-collection was cultivated by Kemp (no. 556 1781), it is possible that all the fruitbodies in the holotype collection may have developed from one and the same cultured mycelium. Alternatively, the basidiocarps may originate from the second culture mentioned in the original description (Scotland, Cumberland, Wigton, no date).
In the original description Watling noted somewhat larger spores (10.5--12.5 x 6--7.5 µm) and basidia much broader (10--12 µm) than were found in the type study.

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