Pileus just before expanding up to 30 x 20 mm, ovoid, sometimes with truncate apex and irregular somewhat lobed margin, rather pale grey (Mu. 5 Y 6/1) at margin to somewhat darker (5 Y 5/1) near apex, but slightly more brownish although not as brown as 2.5 Y 6/2 to 5/2 in Bas 5813, rather more brown (7.5 YR 3/2 to 10 YR 4/3) in Uljé 1062, deeply and densely sulcate at margin, sulcate striate near centre, with appressed (but in young buds suberect), long, thin, fibrillose, ochraceous to salmon-ochraceous (10 YR 7/4 to 7/6) velar scales, condensed to a thin felted salmon-ochraceous patch at centre; margin of cap in early stages loosing contact with stem; pileus up to c. 50 mm when expanded. Lamellae: L = 36-41, l = 1-3(-5), crowded, free, rather narrow (up to 4 mm wide), already in young buds fairly dark chocolate-brown (7.5 YR 3/2), finally dark greyish purple-brown (5 YR 2/2) with thin, pale ochraceous subflocculose edge; pleurocystidia visible with handlens). Stipe up to 80 x 5.5 mm, tapering upwards, hollow, subfasciculate to fasciculate, in some specimens with thin, up to 12 mm long pseudorhiza, slightly greyed whitish, densely fibrillose, with ochraceous tinge because of rather deeply ochraceous yellow superficial fibrils (under lens), especially near base sometimes with a few incomplete, pale ochraceous, floccose girdles or many small, similarly coloured scales. Context ñ chocolate brown in centre of cap, slightly more greyish purple-brown in base of stipe, and paler along cavity of stipe; rest pale. Smell indistinct, weakly fungoid. Taste subraphanoid with somewhat bitterish, unpleased aftertaste. Spore print not available.
Spores [100,5,3] 8.3-13.4 x 5.7-7.3 µm (L x B), av. L= 9.4-12.3, av. B= 6.1-6.8 µm, Q= 1.45-2.10, av. Q= 1.55-1.85, red-brown under microscope (not as blackish brown as in C. lagopus), ellipsoid to ovoid; germ pore central, 1.5-1.8 µm wide. Basidia 15-38 x 8-11 µm, 4-spored. Pseudoparaphyses 3-5(-6) around each basidium. Pleurocystidia 50-140 x 20-50 µm, elongate ellipsoid, subglobose, cylindrical or broadly fusiform. Cheilocystidia 30-120 x 15-50 µm, in very young pileus subglobose or vesiculose, later rather more elongate or ellipsoid, clavate, oblong, vesiculose or cylindrical. Pileipellis consisting of repent radial chains of ñ cylindrical to inflate cells, 8-26 µm wide. Veil made up of parallel, yellowish, granular-incrusted hyphae of 45-200 x 7-20 µm large elements, often somewhat fusiform, not or only slightly constricted at septa. Incrustations on velar hyphae persistent in HCl 10% and alcohol, loosening in KOH and NH4OH and dissolving in Melzer's reagent. Clamp-connections present.
Coprinus ochraceolanatus is rather close to C. lagopus, but differs in having more slender and densely incrusted velar cells (up to 20 µm wide), whereas C. lagopus has smooth velar cells which are much more inflated (up to 40 µm wide). Macroscopically the colour of the veil of C. ochraceolanatus is yellowish ochre, in C. lagopus whitish or greyish, more rarely pale yellow but then the hyphal walls are not incrusted.
The length of the spores of C. ochraceolanatus shows a great deal of variation. In Bas 5813 the spores measure 8.3-11.8 x 5.8-6.8 µm, with a quotient of 1.45-1.90. The other collections examined have spores with a length up to c. 13 µm, whereas the breadth of the spores is very constant in all collections. Consequently the L/B-quotient is 1.50-2.10. Such a difference in size of the spores is not unusual in Coprinus and therefore we accept the collections with spores up to 13 µm long as to belong to C. ochraceolanatus also, because they share with the type-collection the yellow, granular-incrusted, 7-20 µm wide hyphae of the universal veil.
Kemp (1975a: 382; 1975b: 62) introduced the reactions of monokaryotic hyphae to oidia in cultures as a way of testing the degree of relationship among species of Coprinus sect. Lanatuli.
Three interspecific reactions are possible: 1. hyphal tips of one species do not curve to grow towards oidia of another species ('no homing'); 2. hyphal tips of one species curve to grow towards oidia of another species ('homing'); 3. hyphal tips of one species grow towards oidia of another species and fuse with these, but the fusion is lethal ('homing and lethal'). Kemp considers case 3 as indicating the highest degree of relationship and case 1 as the lowest.
Coprinus ochraceolanatus (in Kemp's papers provisionally called C. ochraceovelatus, 1975a: 380) was tested in this respect against nine other species of sect. Lanatuli. In none of the tests with C. ochraceolanatus homing plus a lethal reaction occurred. In fact in most tests there was no homing at all. In three cases there was homing of hyphae towards conidia of C. ochraceolanatus, viz. with C. cinereus, C. macrocephalus, and C. radiatus, but in the reciprocal tests hyphae of C. ochraceolanatus showed no homing to conidia of any of the species involved.
Thus Kemp's tests strongly support the taxonomic value of C. ochraceolanatus as a species.